Yonge Subway Extension
Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
January 2009
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
TABLE OF CONTENTS
Page
PREFACE.......................................................................................................................................1
1.
INTRODUCTION..............................................................................................................2
2.
EAST DON RIVER CROSSING .....................................................................................2
2.1
Generation of Alignments....................................................................................... 2
2.2
Generation of Alternatives...................................................................................... 2
3.
ANALYSIS AND EVALUATION ...................................................................................4
3.1
Assessment of East Don River Crossing Alternatives............................................ 4
3.2
Evaluation of East Don River Crossing Alternatives ............................................. 4
3.2.1 Embankment Alternative versus Bridge Alternative .................................. 4
3.2.2 Bridge Alternative versus Tunnel Alternative ............................................ 5
4.
RECOMMENDATION ON THE PREFERRED ALTERNATIVE.............................7
5.
CONSULTATION .............................................................................................................8
5.1
Public and Stakeholder Consultation ...................................................................... 8
5.2
Refinements suggested during Consultation........................................................... 8
6.
CONSTRUCTION STAGING .......................................................................................10
6.1
Existing Conditions............................................................................................... 10
6.2
Traffic Management during Construction ............................................................ 10
6.3
Construction Stage 1 ............................................................................................. 10
6.4
Construction Stage 2 ............................................................................................. 10
6.5
Construction Stage 3 ............................................................................................. 10
APPENDICES
Appendix 1 - Assessment of East Don River Crossing Alternatives
Appendix 2 – Evaluation of East Don River Crossing Alternatives: Bridge -vs- Tunnel
York Region Rapid Transit Corporation
January 28, 2009
Page i
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
PREFACE
The Regional Municipality of York, City of Toronto and the Toronto
Transit Commission (TTC), in partnership with York Region Rapid
Transit Corporation, have completed a Conceptual Design and
Functional Planning Study for a proposed extension of the Yonge
Street Subway. The intent of the study was to undertake preliminary
planning in preparation for a Transit Project Assessment for the
proposed subway extension.
On June 15, 2007, the Province of Ontario announced $17.5 billion
in funding for transit projects for the Greater Toronto Area and
Hamilton. Named ‘MoveOntario 2020’, the provincial transit plan
includes funding for an extension of the Yonge Street Subway from
its current terminus at Finch Station in the City of Toronto to
Highway 7 (Richmond Hill Centre) in the Town of Richmond Hill.
As a result, on June 21, 2007, York Region Council authorized
commencement of a Conceptual Planning and Functional Design
Study in coordination with the City of Toronto for the timely
extension of the subway.
The scope of Conceptual Design and Functional Planning was to
examine and evaluate possible vertical and horizontal alignment
alternatives, station locations, and associated surface facilities along
the corridor in consultation with public and government
stakeholders. The goal was to develop a technically feasible
solution and the results would serve as the basis that defines the
Transit Project. As part of the Transit Project Assessment process,
an Environmental Project Report is being prepared. It is intended
that the Environmental Project Report will be completed and
formally submitted to the province in February 2009.
This Technical Report is one of a series of reports/papers prepared
for discussion purposes. The reports are as follows:
•
Station Location Analysis
•
East Don River Crossing Alternatives
•
Richmond Hill Centre Alignment Alternatives
•
Station Layout Concepts
York Region Rapid Transit Corporation
January 28, 2009
Page 1
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
1.
Technical Report
East Don River Crossing Alternatives
INTRODUCTION
Development of the East Don River Crossing Alignment component of the Yonge
Subway Extension transit project is summarized including the alternative generation and
evaluation process, the rationale for the Preferred Alternative and recommended issues
for consideration during the Transit Project Assessment process.
2.
EAST DON RIVER CROSSING
The East Don River is one of the two main branches that form the Don River Watershed:
a significant watercourse system and an environmentally-sensitive feature. The river is
situated in a valley with wide open embankments on both sides. The Ladies’ Golf Club of
Toronto is located on the east side of Yonge Street, while the Thornhill Country Club is
situated on the west side. The East Don River flows through a large concrete arch culvert
which supports the existing Yonge Street roadway in the Thornhill Heritage District.
2.1
Generation of Alignments
Horizontal Alignment
The subway alignment is expected to stay within the Yonge Street right-of-way from
Finch Avenue north to the vicinity of Highway 407 mainly to avoid effects on private
property, maintaining straight geometry; therefore, alternatives for the horizontal
alignment at the East Don River Crossing were limited to the vicinity of the existing
Yonge Street right-of-way.
Vertical Alignment
Alternatives for crossing over the river may include an elevated, combined road / subway
structure with a minimal valley floor footprint or a more intrusive culvert structure with a
significant valley floor footprint. Alternatives for crossing under the river were limited to
a tunnelled alternative due to environmental sensitivity and the potential effects of
standard methods of construction. The vertical profile under the East Don River must
provide sufficient vertical clearance from the existing culvert structure in order to ensure
stability during tunnelling. As a result, three primary alternatives were generated for the
vertical alignment at the East Don River Crossing.
2.2
Generation of Alternatives
•
Bridge Alternative – an above ground alternative comprised of an elevated
structure for both the subway and the roadway with the roadway running on top.
The subway crosses the river and continues underground.
•
Embankment Alternative – an above ground alternative comprised of an
embankment structure which contains the subway crossing over the existing
concrete arch culvert with the roadway running along the top of the embankment.
The subway crosses the river and continues underground north and south of the
river valley.
•
Tunnel Alternative – a below ground alternative which tunnels under the river,
leaving Yonge Street, the concrete arch culvert and the valley undisturbed.
York Region Rapid Transit Corporation
January 28, 2009
Page 2
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
Figure 2.2-1 East Don River – Bridge Alternative – Concept Only
Figure 2.2-2 East Don River – Embankment Alternative – Concept Only
Figure 2.2-3 East Don River – Tunnel Alternative – Concept Only
York Region Rapid Transit Corporation
January 28, 2009
Page 3
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
3.
3.1
Technical Report
East Don River Crossing Alternatives
ANALYSIS AND EVALUATION
Assessment of East Don River Crossing Alternatives
The study team undertook a detailed technical assessment of the three alternatives based
on assessment factors, indicators and measures identified for the categories of SocialEconomic Considerations, Transportation Opportunities, Technical / Constructability,
Cultural Environment and Natural Environment.
Appendix 1 contains the results of the complete analysis, which outline the key decision
relevant factors as well as other factors (greyed out) which had no effect on the selection
of a preferred alternative from the three alternatives.
3.2
3.2.1
Evaluation of East Don River Crossing Alternatives
Embankment Alternative versus Bridge Alternative
The Technical Team evaluated the bridge alternative versus the embankment alternative.
The key differences can be summarized as follows:
•
A bridge is preferred by the Toronto Region Conservation Authority as it provides
the greatest opportunity to naturalize the valley system, including a net benefit to
the natural environment. Bridge piers and abutments would have a significantly
smaller footprint in the valley than an embankment and would provide better
opportunity for restoring the valley edges and facilitating the movement of
wildlife.
•
A bridge offers an opportunity to complement existing heritage characteristics by
creating a heritage gateway feature and incorporating heritage design details into
the final design of the bridge structure responding to its role in the community.
•
A bridge has higher potential for noise and vibration effects. However, these
effects can be mitigated through measures such as subway track treatments and
partial or complete subway enclosure. The Technical Team has initiated an
analysis of existing and potential noise and vibration effects in accordance with
the Transit Project Assessment requirements. Results of this technical analysis
will be documented in the Environmental Project Report.
•
Although the embankment alternative would require replacement of the existing
culvert, high-retaining walls and significant earthworks, a bridge would be a more
expensive alternative. However, at this conceptual stage of design, the cost
differentials of the alternatives are not considered a significant decision factor.
After comparing the effects and taking into account stakeholder and public support for renaturalizing the East Don River and valley; and for the opportunity to enhance the
heritage characteristics of the East Don River crossing, the Technical Team concluded
that a bridge structure is preferred over an embankment and culvert structure, and
proceeded to the evaluation of the bridge alternative with the tunnel alternative.
York Region Rapid Transit Corporation
January 28, 2009
Page 4
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
3.2.2
Technical Report
East Don River Crossing Alternatives
Bridge Alternative versus Tunnel Alternative
The Technical Team evaluated the bridge alternative versus the tunnel alternative,
summarized in Appendix 2. The key decision relevant factors are elaborated on below:
Subway Station Depth, User Convenience, and Safety
Subway station depth has a significant impact on user convenience, subway evacuation
response time and station construction cost. Deeper subway stations increase passenger
intermodal transfer time, reducing transit efficiency, and resulting in longer and more
difficult evacuation in the event of emergencies. Station construction costs increase with
greater depth at a rate that is of the order of one million dollars per additional one metre
depth, over and above the cost of all other station facilities. For these key reasons it is
important to keep subway stations as shallow as possible.
The subway elevation at the East Don River crossing and the location and depth of
stations on either side of the East Don River Valley are interdependent due to
requirements to maintain standard-track gradients. A maximum gradient of 3.5% was
used for running sections of track and a much lower maximum of 0.3% for station areas
as per TTC standards for subways. These and other standards were applied to the tunnel
alternative, which crosses well under the East Don River for environmental and structural
reasons, and resulted in subway stations on either side of the East Don River valley that
were in the order of 35m deep. This depth is almost twice the depth of the existing
deepest TTC subway station (Bayview Avenue at 18.6 metres). The majority of the
existing stations in the TTC system are less than 13 metres deep. In contrast, the
standards applied to the bridge alternative resulted in subway stations at normal depths
with corresponding station benefits with respect to user convenience, emergency
evacuation and station cost, which were balanced against other effects of the bridge
alternative. Even if no station is built on either side of the valley (Centre or Royal
Orchard), surface emergency exit buildings would be built to meet the Ontario Building
Code for underground rapid transit facilities and TTC design standards, requiring a
maximum distance from emergency exit to emergency exit or emergency exit to station
of 762 metres, representing significant evacuation challenges in the case of emergencies.
Natural Environment
The bridge alternative is preferred by the Toronto Region Conservation Authority as it
provides the greatest opportunity to naturalize the valley system, providing a net benefit
to the natural environment. While there may be the potential for minor effects on the
natural environment during construction, long-term effects of the bridge alternative can
be mitigated with an appropriate revegetation / naturalization plan enhancing the
environmentally sensitive areas, natural heritage systems, wildlife corridors and
terrestrial features. Long-term effects of the bridge alternative on fisheries and aquatic
resources could be mitigated with a bridge design that spans the river. While the tunnel
alternative does not impact these aspects of the natural environment, it also does not
present opportunity for enhancement.
The tunnel alternative would likely have a greater impact on underground water than the
bridge alternative. While the bridge piers have the potential to impact ground water flow,
the tunnel alternative would likely require ongoing dewatering as part of normal subway
operations and maintenance. Further, the tunnel alternative would require stations at
York Region Rapid Transit Corporation
January 28, 2009
Page 5
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
significantly greater depths on either side of the East Don River valley increasing the
magnitude of the excavations and dewatering necessary for construction purposes.
Road Facilities
The existing Yonge Street gradients across the East Don River valley are steep and create
difficult winter operating conditions for road users and pedestrians. The bridge
alternative provides the opportunity to raise the profile of Yonge Street, placing the
roadway on top of the subway support structure and mitigating the current unfavourable
winter operating conditions. The tunnel alternative would have no impact on the existing
Yonge Street road profile and winter operations would continue to be affected by the road
grades on either side of the valley.
Residential and Commercial Property Access
The bridge alternative will temporarily affect some private / commercial accesses during
construction, such as the Ladies’ Golf Club of Toronto. However, construction impacts
can be mitigated through appropriate construction staging and traffic management.
Long-term effects of the bridge alternative on private / commercial accesses depend on
the length of the bridge. A longer bridge would have greater impacts on property access
and heritage character, in particular access to the Ladies’ Golf Club of Toronto and
access to heritage properties to the southwest on Yonge Street. In the case of a longer
bridge the Ladies’ Golf Club of Toronto access would need to be relocated further south
to utilize the bridge approach embankment effectively or be provided through a more
complex access structure. A longer bridge would require the construction of high
retaining walls at the Yonge Street frontage to the heritage properties to the southwest, as
well as the relocation of one heritage property access to a parallel-side street.
The proposed shorter bridge is expected to be in the order of 150 metres long and
minimizes long term impacts on property access, achieving a less significant relocation of
the access to the Ladies’ Golf Club of Toronto within the bridge approach embankment,
and eliminating access relocation and retaining walls at the heritage properties, with the
exception of a one-metre-high retaining wall at 7822 Yonge Street. The shorter bridge
minimizes grading impacts on adjacent land uses, maintains existing access to adjacent
land use and provides sufficient vertical clearance to accommodate river flood levels and
animal / human passage. The tunnel alternative would have no impact on residential and
commercial property access.
Heritage Features
The bridge alternative would impact the heritage structure associated with the interurban
electric railway established along Yonge Street from Toronto in the late 1890’s. The
structure would require relocation in order to accommodate bridge construction. Effects
and mitigation measures are being studied and will be reported as part of the Transit
Project Assessment process. The tunnel alternative would have no impact on this
heritage structure.
Based on the above key decision relevant factors the Technical Team concluded that a
bridge structure over the East Don River is preferred over a subway tunnel under the
valley.
York Region Rapid Transit Corporation
January 28, 2009
Page 6
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
4.
Technical Report
East Don River Crossing Alternatives
RECOMMENDATION ON THE PREFERRED ALTERNATIVE
The recommended crossing is a bridge over the East Don River such as that shown in
Figure 4-1. The advantages of the bridge alternative include:
•
Shallower subway stations and emergency exit buildings on either side of the East
Don River to effect easier and quicker tunnel evacuations in the event of an
emergency, and to provide easier station access during normal use.
•
Improvement of the Yonge Street road vertical alignment, reducing the gradients
which cause pedestrian and traffic hazards in winter and affect bus operations.
•
Removal of existing culvert structures within the East Don River creating
opportunities to naturalize the river valley, re-establish wildlife corridors and
improve east / west access through the valley for recreational purposes.
•
Improved vertical alignment of the subway with associated benefits to subway
operations.
•
Reduced effect on groundwater during and post-construction as well as a
reduction in groundwater pumping requirements from subway tunnels that are at
shallower depth.
Figure 4-1 East Don River – Bridge Alternative – Preferred Alternative
The vertical profile of the bridge indicated in Figure 4-1 will be illustrated in more detail
once conceptual design principles have been developed for this potentially significant
community feature.
York Region Rapid Transit Corporation
January 28, 2009
Page 7
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
5.
5.1
Technical Report
East Don River Crossing Alternatives
CONSULTATION
Public and Stakeholder Consultation
Public and stakeholder consultations were held from June-September 2008 to discuss
stations, station locations, the East Don River crossing and alignments into the Richmond
Hill Centre. On June 17 & 18, 2008, a Public Consultation Centre was held to introduce
the Yonge Subway project and was attended by approximately 220 people. More
focussed public workshops were held on July 31, 2008, and August 26, 2008, which were
attended by 42 and 52 people, respectively. On September 25, 2008, a Public
Consultation Centre was held to update the public and present the Preferred Alternative.
The PCC was attended by approximately 400 people.
5.2
Refinements suggested during Consultation
Preliminary concepts of the three primary Bridge, Embankment and Tunnel alternatives
were presented at the June 17 & 18, 2008, Public Consultation Centre, where the public
preference was for an alignment for the subway over the East Don River / Valley with a
bridge. A range of bridge design concepts were presented at the public workshop on July
31, 2008, including both heritage and modern design themes. Participants were divided
into 4 groups that worked independently on the entire subway extension to identify their
preferred subway extension concept. The majority of participants favoured the bridge
alternative, particularly for the opportunity it provides to significantly elevate the Yonge
Street road alignment and mitigate currently adverse winter operating conditions.
Participants also favoured a heritage design theme for the bridge.
While a bridge alternative is highly visual and provides an opportunity to create a
gateway structure / feature for the community, it also increases the potential for a change
in character of the heritage district. One way to mitigate the visual effects of the bridge
alternative is to incorporate heritage features in the design of the bridge. In this regard,
participants at the July 31, 2008, Public Workshop suggested that heritage attributes of
the Thoreau MacDonald etching (see Figure 5.2-1) be considered during the design
stages for an East Don River bridge alternative. Apart from heritage issues, an important
design criterion is the potential need to visually inspect the subway concrete track bed
system from the Yonge Street road right-of-way using equipment that extends over the
east and west sides of the bridge structure to inspect the subway below.
Figure 5.2-1 Thoreau MacDonald Etching
York Region Rapid Transit Corporation
January 28, 2009
Page 8
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
The detailed technical assessment of the Bridge, Embankment and Tunnel alternatives
was presented along with the draft recommended subway extension project for comment
at the second public workshop on August 26, 2008. The majority of participants
confirmed the key decision factors listed in Appendix 1 and the selection of the Bridge
Alternative with a heritage design theme as the Preferred Alternative.
Figure 5.2-2 Examples of Heritage Bridge Design Presented at Public Workshops
The preferred Bridge Alternative and supporting rationale was presented at the
September 25, 2008, Public Consultation Centre, where over 200 participants, both onsite and via the internet, were given an opportunity to participate interactively and
indicate some preferences with respect to the Bridge Alternative. Through interactive
questioning participants indicated that “Removing the steep slopes on the existing Yonge
Street road to provide safer and smoother traffic movements” was more important than
“Connecting the communities on both sides of the valley, e.g., easier walking paths” and
“Removing the culvert and embankment, and restoring the natural function of the river
valley”. Participants also provided interactive feedback on what kinds of bridge features
reflect a heritage bridge to them.
Through consultation, it has been determined that the characteristics of the bridge should
reflect the heritage nature of the surrounding area, address noise concerns and preserve
access to the local golf clubs and other entrances along Yonge Street. The specific
characteristics of the bridge, including landowner access, will continue to be subject to
public, municipal and stakeholder review and consultation going forward.
York Region Rapid Transit Corporation
January 28, 2009
Page 9
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
6.
6.1
Technical Report
East Don River Crossing Alternatives
CONSTRUCTION STAGING
Existing Conditions
The East Don River is situated in a valley with wide open embankments on both sides
and flows through a 14m span concrete arch culvert under Yonge Street. Yonge Street
crosses the East Don River in the Thornhill Heritage District, with the Ladies’ Golf Club
of Toronto located on the east side of Yonge Street and the Thornhill Country Club
located on the west side.
The existing Yonge Street roadway is supported longitudinally on an embankment across
the East Don River valley. The existing Yonge Street roadway cross section consists of
two general purpose lanes in each of the northbound and southbound directions and a
centre double left turn lane.
6.2
Traffic Management during Construction
A preliminary construction staging strategy was developed to confirm construction
feasibility and better understand potential effects and cost. During the preliminary design
and detailed design stages, the design of the bridge (and the resulting traffic staging
plans) will be developed in more detail in consultation with York Region, the City of
Vaughan, the Town of Markham and the TTC including opportunities for public input at
the appropriate design stages. The preliminary traffic staging concept involves a 4-lane
traffic detour being built on the west side of Yonge Street adjacent to the bridge and
bridge approaches and will follow the existing profile of Yonge Street. Care will be taken
during construction to minimize environmental effects and to maintain continuous
property access. Three construction stages are recommended at this time, outlined briefly
below.
6.3
Construction Stage 1
A 4-lane traffic detour and a pedestrian walkway will be constructed on the west side of
Yonge Street. The existing East Don River culvert extends far enough from Yonge Street
to accommodate 4 lanes of traffic and 2m of construction clearance. The existing culvert
outlet to the south west of the East Don River crossing will not be affected by the
construction of the detour. Temporary bridging of the East Don River may be required to
accommodate the pedestrian walkway. Traffic will still circulate on Yonge Street.
6.4
Construction Stage 2
The bridge and northbound approaches will be constructed. General traffic will circulate
on the 4 lane detour built in Stage 1 including temporary access to the Ladies Golf Club
off of the existing embankment.
6.5
Construction Stage 3
Southbound approaches and ultimate Ladies Golf Club access (conditions similar to the
existing access) will be constructed. Northbound traffic will circulate on new bridge;
southbound traffic will still use the detour.
York Region Rapid Transit Corporation
January 28, 2009
Page 10
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
APPENDIX 1
Assessment of East Don River Crossing
Alternatives
York Region Rapid Transit Corporation
January 28, 2009
Page 11
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Embankment
Tunnel
1.0 Social-Economic Considerations
1.1 Population+Employment density within station zone of influence
EXISTING population+employment density Number of medium-rise
residential and high-rise
within 500m radius of station
residential towers as
proxy for measuring
density
Number of medium-rise
FUTURE (2021) population+employment
density within 500m radius of station based residential and high-rise
residential towers as
on current forecasts
proxy for measuring
density
Quantifies the
need/justification for a
station at this location
today
All alternatives yield similar results - this indicator is related to selection of station locations
Existing conditions
All alternatives yield similar results - this indicator is related to selection of station locations
Quantifies the
Future projection
need/justification for a
station at this location in
the future
1.2 Major trip origins and destinations within station zone of influence
EXISTING commercial, employment, or
institutional attractions within 500m radius
Name
NEW commercial, employment, or
institutional attractions within 500m radius
Name
Identifies any major trip
generator within the
station catchment area
Identifies any major trip
generator within a
station's zone of
influence
Existing condition
All alternatives yield similar results - this indicator is related to selection of station locations
Known/planned future
condition
All alternatives yield similar results - this indicator is related to selection of station locations
1.3 Potential to stimulate transit supportive development within station zone of influence
Availability of large parcels of land for
redevelopment
Description - area (m2)
Redevelopment potential within station zone low, medium, high
of influence (500m radius)
Assesses potential for
redevelopment within a
station's zone of
influence
Assesses potential for
redevelopment within a
station's zone of
influence
Existing conditions
All alternatives yield similar results - this indicator is related to selection of station locations
Existing conditions
All alternatives yield similar results - this indicator is related to selection of station locations
1.4 Effects on daily Yonge Street vehicular and pedestrian users
Traffic impact during construction
Description
Availability of diversion
routes during
construction
Effects on pedestrian users on Yonge
Street
Description
Assesses the potential Future conditions
effects on quality of
pedestrian connection
on Yonge Street across
the valley
York Region Rapid Transit Corporation
Existing conditions
Significant effects on vehicular and
pedestrian access during
construction. Optimum staging plan
will be required to mitigate effects to
Yonge Street circulation
Improves quality of pedestrian
connection. However, pedestrian
experience on Yonge Street is on
bridge – limited opportunity for
connectivity with the valley.
January 28, 2009
Significant effects on vehicular and
pedestrian access during
construction. Optimum staging plan
will be required to mitigate effects to
Yonge Street circulation
Improves quality of pedestrian
connection - less than bridge
Insignificant - the impacts are limited
only to potential emergency exits
whose positions can be optimised.
No change
Page 12
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Embankment
Tunnel
1.0 Social-Economic Considerations
1.5 Potential impacts to residential and commercial properties
Temporary impact to residences in the
area
Description
Extent to which the
Existing condition
residential community is
affected by the
alternative
Number of commercial properties
impacted / displaced
Number, Description
Number of residential propert ies
impacted / displaced
Number; Description
Extent to which local
businesses may be
affected
Extent to which stable
residential properties
may be affected
Existing condition
Inconvenience to Condominium
Complex and residences south of the
crossing during construction.
Temporary access road to Toronto
Ladies' Golf Club would be required.
Inconvenience to Condominium
No potential effect
Complex and residences south of the
crossing during construction.
Temporary access road to Toronto
Ladies' Golf Club would be required.
None
None
Existing condition
1
None
1
0
South-West: Yonge 7822 1.0m
ret.wall
South-West: Yonge 7822 1.0m
ret.wall
None
1.6 Potential effects on local noise, vibration, and air quality
Pot ential effect s of subw ay
Descript ion
Existing condition
Changes in noise,
vibrat ion and air quality
Potential for moderate impacts if
subway is in an open structure,
however impacts can be mitigated
Lower - since the subway will be
crossing over the river valley within
an enclosed structure slightly above
the existing Yonge Street elevation,
potential effects can be mitigated
lowest impacts - since the subway
would be crossing deep underground,
potential effects are expected to be
minimal
Pot ential effect s of traff ic
Descript ion
Existing condition
Changes in noise,
vibrat ion and air quality
Descript ion
Existing conditions
Changes in noise,
vibrat ion and air quality
Potential for low effects as structure
is closer to nearby residential
properties
Potential for road construction
impacts
No change - existing conditions
Pot ential effect s due t o const ruction
Potential for low effects as structure
is closer to nearby residential
properties
Potential for road construction
impacts
None
None
None
None
None
None
low impacts - since the subway would
be crossing deep underground,
potential effects are expected to be
minimal
1.7 Potential impacts to schools, places of worship, and unique community features
Communit y facilities impacted / displaced Number; Description
Institutional f acilities impacted /
displaced
Number; Description
York Region Rapid Transit Corporation
Extent to which
Existing condition
community/recreational
facilities may be
displaced
Extent to which
Existing condition
institutional facilities may
be displaced
January 28, 2009
Page 13
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Measures the potential
range of capital cost
associated w ith each
option
Measures the potential
range of capital cost
associated w ith each
option
Low est cost option:
rebuild existing
culvert/embankment to
accommodate subw ay
Low est cost option:
rebuild existing
culvert/embankment to
accommodate subw ay
Measures the potential
range of operations and
maintenance cost
associated w ith each
option
Low est cost option:
rebuild existing
culvert/embankment to
accommodate subw ay
Bridge
Embankment
Tunnel
Capital cost greater than
embankment and tunnel options
Baseline, low est capital cost
Capital cost greater than
embankment option but low er than
bridge option
Capital cost greater than
embankment and tunnel options
Baseline, low est capital cost
Operations and maintenance cost
greater than embankment option
but low er than tunnel option
Baseline, low est operations and
maintenance cost
Capital cost greater than
embankment option but low er than
bridge option. Capital cost greater
than tunnel option w ith no station
w ithin Heritage District.
Operations and maintenance cost
greater than bridge and
embankment options
Potential to impact sites with high
contamination potential. Impact can
be mitigated.
1.0 Social-Economic Considerations
1.8 Achieve reasonable costs
Range of capital cost (no station within
Heritage District)
High level range PRELIMINARY
Range of capital cost (one station within
Heritage District)
High level range PRELIMINARY
Range of operations and maintenance cost High level range PRELIMINARY
1.9 Minimize potential cost associated with clean-up of potentially contaminated sites
Number of sites with High potential for
contamination (i.e. landfill or gas service
station on property) that may be affected
Description
Measures the potential Based on desktop
review of available
risk associated w ith
need for mitigation of data/resources
contamination.
Potential to impact sites with high
contamination potential. Impact can
be mitigated.
Number of sites with Medium potential for
contamination (i.e. property with record of
previous spill) that may be affected
Description
See above
See above
Potential to impact sites with medium Potential to impact sites with medium Low impact to surface contaminated
contamination potential. Impact can contamination potential. Impact can sites as subway would be tunneled.
be mitigated.
be mitigated.
Number of sites with Low potential for
Description
contamination (i.e. average commercial
property) that may be affected
Number of Gas Conflict Areas (i.e. contact Description
with underground gas pipeline) that may be
affected
Number of Spill sites that may be affected Description
See above
See above
See above
See above
Potential to impact sites with low
Potential to impact sites with low
contamination potential. Impact can contamination potential. Impact can
be mitigated.
be mitigated.
Potential to impact gas conflict areas. Potential to impact gas conflict areas.
Impact can be mitigated.
Impact can be mitigated.
See above
See above
Potential to impact sites with high
contamination potential.
Potential to impact sites with high
contamination potential.
Low impact to surface contaminated
sites as subway would be tunneled.
See above
See above
Potential to impact sites with high
contamination potential.
Potential to impact sites with high
contamination potential.
Low impact to surface contaminated
sites as subway would be tunneled.
Number of Fuel Storage sites that may be
affected
Description
York Region Rapid Transit Corporation
January 28, 2009
Low impact to surface contaminated
sites as subway would be tunneled.
Low impact to surface contaminated
sites as subway would be tunneled.
Low impact to surface contaminated
sites as subway would be tunneled.
Page 14
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Embankment
Tunnel
2.0 Transportation Opportunities
2.1 Transit Network Connectivity
Local transit connections
Route names and
existing typical daily
ridership
Inter-Regional transit connections
Route names and
existing typical daily
ridership
Assesses connectivity
with local transit.
Describes the potential
service coverage a
station could provide
through local transit
connections.
Assesses connectivity
with inter-regional
transit. Describes the
potential service
coverage a station could
provide through interregional transit
connections.
Future local transit
network in the area
All alternatives yield similar results - this indicator is related to selection of station locations
Future inter-regional
transit network in the
area
All alternatives yield similar results - this indicator is related to selection of station locations
2.2 Associated Station Surface Facilities
All alternatives yield similar results - this indicator is related to selection of station locations
Integration of station surface facilities - the
extent to which the alternative can offer a
compact and well-integrated mobility hub
2.3 Effects on Road Facilities
Effect on Yonge Street profile across the
river valley
Improves road profile of Yonge Street
- The alternative provides the
opportunity to raise the profile of
Yonge Street, placing the roadway on
top of the subway support structure
and mitigating the current
unfavourable winter operating
conditions.
Description
Assesses the potential Existing conditions
effects on Yonge Street
as a result of the
undertaking
shallow, deep;
description
Assesses inconvenience Depth of potential station Shallow. Potential station would
to users at deep stations in the area
provide more convenient environment
to users with easier evacuation and
emergency response should it be
necessary.
Improves road profile of Yonge Street No effects - retains existing
- The alternative provides the
conditions
opportunity to raise the profile of
Yonge Street, placing the roadway on
top of the subway support structure
and mitigating the current
unfavourable winter operating
conditions.
2.4 User Accessibility
Effect on station depth, subway user
convenience, and safety
York Region Rapid Transit Corporation
January 28, 2009
Shallow. Potential station would
provide more convenient environment
to users with easier evacuation and
emergency response should it be
necessary.
Deep. Potential station would be
twice as deep as the current deepest
TTC station; providing less
convenient access and more difficult
evacuation should it be necessary.
Page 15
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Embankment
Tunnel
3.0 Technical / Constructability
3.1 Compliance with design standards & criteria
Horizontal and vertical alignments
Description
Compliance w ith
technical design
standards
TTC Design Standards
Complies with TTC standards for 80 KPH design speed.
Description
Assesses potential
physical limitation on
the surface for
construction
Existing conditions
Complicated and limited working area
at the portal sections, approaches to
the bridge and the bridge itself..
Restrictions due to presence of
Heritage District, private property and
river valley.
Limited working area at the portal
No potential surface disturbance
sections, approaches to the bridge
and the bridge itself. Restrictions due
to presence of Heritage District,
private property and river valley.
Impact to Toronto Ladies' Golf Club access Description
Ability to provide
vehicular access
Existing conditions
A temporary access will be required
during construction.
A temporary access will be required
during construction.
Impact to Thornhill Country Club access
Description
Ability to provide
vehicular access
Existing conditions
No effect to main access. Both
permanent and temporary
maintenance access will require realignment
No effect to main access. Temporary No potential effects.
maintenance access required during
construction.
Potential impact to surface and ground
water
Description
Assesses effects to
w ater control along
valley.
Existing conditions
Surface and ground water control
required.
Surface and ground water control
required.
3.2 Constructability
Physical limitation on the surface as it
relates to construction
York Region Rapid Transit Corporation
January 28, 2009
No potential effects.
Ground water control required.
Page 16
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Embankment
Tunnel
4.0 Cultural Environment
4.1 Potential impacts to known archaeological sites
Number of known sites in proximity of
alignment
Number
Assess the potential for Existing condition
causing adverse effects
on any known
archaeological site
Minor potential impact. A Stage 2
Archaeological Assessment would
have to be undertaken to ensure
there are no significant cultural
resources.
Minor potential impact. A Stage 2
Archaeological Assessment would
have to be undertaken to ensure
there are no significant cultural
resources.
No impacts as the subway would be
tunneled.
Area of archaeological potential that have
previously been undisturbed by
development
Hectares
Assess the potential for Existing condition
causing adverse effects
on any known area of
archaeological potential
Minor potential impact. A Stage 2
Archaeological Assessment would
have to be undertaken to ensure
there are no significant cultural
resources.
Minor potential impact. A Stage 2
Archaeological Assessment would
have to be undertaken to ensure
there are no significant cultural
resources.
No impacts as the subway would be
tunneled.
Description
Existing condition
Assess the potential
effects on any significant
built-heritage and
cultural heritage features
in the area
Potential effect to an old railway
shelter located on north-east side of
the crossing. Given the nature of the
shelter the risk can be fully mitigated.
Potential effect to an old railway
No potential effects.
shelter located on north-east side of
the crossing. Given the nature of the
shelter the risk can be fully mitigated.
Potential impact to local visual connections Description
(views and vistas)
Assess the potential
Existing condition
effects on local
community current views
Bridge will have the highest visual
effects - has opportunity to create a
gateway structure / feature
Raised embankment will have a lower No change to existing views
visual effect.
Potential for resulting in a change in
character of the heritage district
Extent to which
Existing condition
character of the heritage
district could be affected
by the alternative
Presence of bridge will have an effect Less significant potential effects are
to the character of the heritage
anticipated
district. A structure with a heritage
design is being considered.
No potential effects.
No significant effects are anticipated
No potential effects.
4.2 Effects on heritage features
Potential for displacing or disrupting built
heritage features
none, lower, higher
4.3 Potential impacts to parks and recreation sites
Potential long-term impact on golf clubs from a business perspective
Description
Assess the potential
effects on local golf
courses as a result of
the alternative
Local parks and trails impacted / displaced
Description
Measures the potential Existing condition
for causing adverse
effects on any park and
trail in the area
York Region Rapid Transit Corporation
Existing condition
No significant effects are anticipated
Bridge construction will include
Moderate impact to local park on
naturalization of the creek; moderate north-east side of crossing during
impact to local park on north-east
construction.
side of crossing during construction.
January 28, 2009
No potential effects.
Page 17
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
ASSESSMENT OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Embankment
Tunnel
5.0 Natural Environment
5.1 Potential impacts to Environmentally Sensitive Areas, Natural Heritage Systems, and Wildlife Corridors
Provincial/Federal natural features /
environmentally significant features
potentially affected
Description
Assess the potential
effects on any
significant natural
resources / features, if
present
Existing condition
There are no Provincial or Federal natural features / environmentally significant features within the area
Regional/Local natural features /
environmentally significant features
potentially affected
Description
Assess the potential
effects on any
significant natural
resources / features, if
present
Existing condition
Potential for minor effects during
construction but long term effects
could be mitigated with an
appropriate
revegetation/naturalization plan.
Enhancement opportunity.
Potential for minor effects during
construction but long term effects
could be mitigated with an
appropriate
revegetation/naturalization plan
No impacts as the subway would be
tunneled.
5.2 Potential impacts to surface water, identified water crossings, drainage features, and areas susceptible to surface water contamination
Potential dow nstream effects on hydraulic Description
conditions in the river valley
Existing condition
Assess the potential
effects on drainage and
w ater control
Potential effects to underground water
Assess potential
dew atering
requirements
Description
Major effects not anticipated.
Major effects not anticipated.
None anticipated
Existing condition
Potential for impacting groundwater
as a result of bridge piers
None anticipated
Potential for impacting groundwater
as a result of tunnel
Assess the potential
effects on terrestrial
features
Existing condition
Potential for minor effects during
construction but long term effects
could be mitigated with an
appropriate
revegetation/naturalization plan.
Enhancement opportunity
Potential for minor effects during
construction but long term effects
could be mitigated with an
appropriate
revegetation/naturalization plan
No impacts as the subway would be
tunneled.
Assess the potential
effects on aqautic
features
Existing condition
Potential for minor effects during
construction but long term effects
could be mitigated with a design
which spans the river.
Potential for minor effects during
construction but long term effects
could be mitigated with a design
which minimizes impact on the
existing river culvert.
No impacts as the subway would be
tunneled.
5.3 Potential impacts to terrestrial features
Habitat potentially displaced or severed
Description
5.4 Potential impacts to fisheries and aquatic resources
Aquatic features potentially affected
Description
Shaded rows indicate criteria that
are not decision-relevant for
selecting station locations
York Region Rapid Transit Corporation
January 28, 2009
Page 18
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
APPENDIX 2
Evaluation of East Don River Crossing
Alternatives: Bridge –vs- Tunnel
York Region Rapid Transit Corporation
January 28, 2009
Page 19
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Tunnel
Significant effects on vehicular and pedestrian
access during construction. Optimum staging
plan will be required to mitigate effects to Yonge
Street circulation
Improves quality of pedestrian connection.
However, pedestrian experience on Yonge Street
is on bridge – limited opportunity for connectivity
with the valley.
Insignificant - the impacts are limited only to
potential emergency exits whose positions can be
optimised.
1.0 Social-Economic Considerations
1.4 Effects on daily Yonge Street vehicular and pedestrian users
Traffic impact during construction
Description
Availability of diversion
routes during
construction
Existing conditions
Effects on pedestrian users on Yonge
Street
Description
Assesses the potential Future conditions
effects on quality of
pedestrian connection
on Yonge Street across
the valley
Evaluation:
No change
1.5 Potential impacts to residential and commercial properties
Temporary impact to residences in the
area
Description
Number of resident ial propert ies
impact ed / displaced
Number; Descript ion
Extent to which the
Existing condition
residential community is
affected by the
alternative
Extent to which stable
Existing condition
residential properties
may be affected
Evaluation:
Inconvenience to Condominium Complex and
No potential effect
residences south of the crossing during
construction. Temporary access road to Toronto
Ladies' Golf Club would be required.
1
South-West: Yonge 7822 1.0m ret.wall
○
0
None
1.6 Potential effects on local noise, vibration, and air quality
Pot ent ial ef fect s of subw ay
Descript ion
Existing condition
Changes in noise,
vibration and air qualit y
Potential for moderate impacts if subway is in an lowest impacts - since the subway would be
open structure, however impacts can be mitigated crossing deep underground, potential effects are
expected to be minimal
Pot ent ial ef fect s of t raff ic
Descript ion
Existing condition
Changes in noise,
vibration and air qualit y
Potential for low effects as structure is closer to
nearby residential properties
No change - existing conditions
Pot ent ial ef fect s due t o const ruct ion
Descript ion
Existing conditions
Changes in noise,
vibration and air qualit y
Potential for road construction impacts
low impacts - since the subway would be crossing
deep underground, potential effects are expected
to be minimal
Evaluation:
York Region Rapid Transit Corporation
January 28, 2009
○
Page 20
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Tunnel
Capital cost greater than embankment and
tunnel options
Capital cost greater than embankment option
but low er than bridge option
Capital cost greater than embankment and
tunnel options
Capital cost greater than embankment option
but low er than bridge option. Capital cost
greater than tunnel option w ith no station
w ithin Heritage District.
Operations and maintenance cost greater than
bridge and embankment options
1.0 Social-Economic Considerations
1.8 Achieve reasonable costs
Range of capital cost (no station within
Heritage District)
High level range PRELIMINARY
Range of capital cost (one station within
Heritage District)
High level range PRELIMINARY
Range of operations and maintenance cost High level range PRELIMINARY
Measures the potential
range of capital cost
associated w ith each
option
Measures the potential
range of capital cost
associated w ith each
option
Measures the potential
range of operations and
maintenance cost
associated w ith each
option
Low est cost option:
rebuild existing
culvert/embankment to
accommodate subw ay
Low est cost option:
rebuild existing
culvert/embankment to
accommodate subw ay
Low est cost option:
rebuild existing
culvert/embankment to
accommodate subw ay
Operations and maintenance cost greater than
embankment option but low er than tunnel
option
Evaluation:
○
○
Potential to impact sites with high contamination
potential. Impact can be mitigated.
Low impact to surface contaminated sites as
subway would be tunneled.
1.9 Minimize potential cost associated with clean-up of potentially contaminated sites
Number of sites with High potential for
contamination (i.e. landfill or gas service
station on property) that may be affected
Description
Measures the potential Based on desktop
review of available
risk associated w ith
data/resources
need for mitigation of
contamination.
Number of sites with Medium potential for
contamination (i.e. property with record of
previous spill) that may be affected
Description
See above
See above
Potential to impact sites with medium
contamination potential. Impact can be mitigated.
Low impact to surface contaminated sites as
subway would be tunneled.
Number of sites with Low potential for
contamination (i.e. average commercial
property) that may be affected
Description
See above
See above
Potential to impact sites with low contamination
potential. Impact can be mitigated.
Low impact to surface contaminated sites as
subway would be tunneled.
Number of Gas Conflict Areas (i.e. contact Description
with underground gas pipeline) that may be
affected
See above
See above
Potential to impact gas conflict areas. Impact can
be mitigated.
Low impact to surface contaminated sites as
subway would be tunneled.
Number of Spill sites that may be affected
Description
See above
See above
Potential to impact sites with high contamination
potential.
Low impact to surface contaminated sites as
subway would be tunneled.
Number of Fuel Storage sites that may be
affected
Description
See above
See above
Potential to impact sites with high contamination
potential.
Low impact to surface contaminated sites as
subway would be tunneled.
○
Evaluation:
SUMMARY:
York Region Rapid Transit Corporation
January 28, 2009
Page 21
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Tunnel
2.0 Transportation Opportunities
2.3 Effects on Road Facilities
Effect on Yonge Street profile across the
river valley
Description
Assesses the potential Existing conditions
effects on Yonge Street
as a result of the
undertaking
Evaluation:
Improves road profile of Yonge Street - The
No effects - retains existing conditions
alternative provides the opportunity to raise the
profile of Yonge Street, placing the roadway on
top of the subway support structure and mitigating
the current unfavourable winter operating
conditions.
2.4 User Accessibility
Effect on station depth, subway user
convenience, and safety
shallow, deep;
description
Assesses inconvenience Depth of potential station Shallow. Potential station would provide more
to users at deep stations in the area
convenient environment to users with easier
evacuation and emergency response should it be
necessary.
Evaluation:
SUMMARY:
Deep. Potential station would be twice as deep as
the current deepest TTC station; providing less
convenient access and more difficult evacuation
should it be necessary.
○
○
3.0 Technical / Constructability
3.2 Constructability
Physical limitation on the surface as it
relates to construction
Description
Impact to Toronto Ladies' Golf Club access Description
Assesses potential
physical limitation on
the surface for
construction
Ability to provide
vehicular access
Existing conditions
Complicated and limited working area at the portal No potential surface disturbance
sections, approaches to the bridge and the bridge
itself.. Restrictions due to presence of Heritage
District, private property and river valley.
Existing conditions
A temporary access will be required during
construction.
No potential effects.
No effect to main access. Both permanent and
temporary maintenance access will require realignment
Surface and ground water control required.
No potential effects.
Impact to Thornhill Country Club access
Description
Ability to provide
vehicular access
Existing conditions
Potential impact to surface and ground
water
Description
Assesses effects to
w ater control along
valley.
Existing conditions
Evaluation:
SUMMARY:
York Region Rapid Transit Corporation
January 28, 2009
○
○
Ground water control required.
Page 22
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Tunnel
4.0 Cultural Environment
4.1 Potential impacts to known archaeological sites
Number of known sites in proximity of
alignment
Number
Area of archaeological potential that have
previously been undisturbed by
development
Hectares
Assess the potential for Existing condition
causing adverse effects
on any known
archaeological site
Assess the potential for Existing condition
causing adverse effects
on any known area of
archaeological potential
Evaluation:
Minor potential impact. A Stage 2 Archaeological No impacts as the subway would be tunneled.
Assessment would have to be undertaken to
ensure there are no significant cultural resources.
Minor potential impact. A Stage 2 Archaeological No impacts as the subway would be tunneled.
Assessment would have to be undertaken to
ensure there are no significant cultural resources.
4.2 Effects on heritage features
Potential for displacing or disrupting built
heritage features
Description
Potential impact to local visual connections Description
(views and vistas)
Potential for resulting in a change in
character of the heritage district
none, lower, higher
Existing condition
Assess the potential
effects on any significant
built-heritage and
cultural heritage features
in the area
Assess the potential
Existing condition
effects on local
community current views
Extent to which
Existing condition
character of the heritage
district could be affected
by the alternative.
Evaluation:
Potential effect to an old railway shelter located on No potential effects.
north-east side of the crossing. Given the nature
of the shelter the risk can be fully mitigated.
Bridge will have the highest visual effects - has
No change to existing views
opportunity to create a gateway structure / feature
No potential effects.
Presence of bridge will have an effect to the
character of the heritage district. A structure with a
heritage design is being considered.
4.3 Potential impacts to parks and recreation sites
Potential long-term impact on golf clubs from a business perspective
Description
Local parks and trails impacted / displaced
Description
Assess the potential
effects on local golf
courses as a result of
the alternative
Measures the potential
for causing adverse
effects on any park and
trail in the area
Existing condition
No significant effects are anticipated
Existing condition
Bridge construction will include naturalization of
No potential effects.
the creek; moderate impact to local park on northeast side of crossing during construction.
Evaluation:
SUMMARY:
York Region Rapid Transit Corporation
January 28, 2009
No potential effects.
Page 23
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Factors/Indicators/Measures
Relevance of Factor
Baseline Value for
Comparison
Bridge
Tunnel
5.0 Natural Environment
5.1 Potential impacts to Environmentally Sensitive Areas, Natural Heritage Systems, and Wildlife Corridors
Regional/Local natural f eatures /
environmentally significant features
potentially affected
Description
Assess the potential
effect s on any
signif icant natural
resources / f eatures, if
present
Existing condition
Evaluation:
Potential for minor effects during construction but No impacts as the subway would be tunneled.
long term effects could be mitigated with an
appropriate revegetation/naturalization plan.
Enhancement opportunity.
5.2 Potential impacts to surface water, identified water crossings, drainage features, and areas susceptible to surface water contamination
Potential dow nstream effects on hydraulic Description
conditions in the river valley
Existing condition
Assess the potential
effect s on drainage and
w ater control
Potential effects to underground water
Assess potential
dew atering
requirements
Description
Existing condition
Evaluation:
Major effects not anticipated.
None anticipated
Potential for impacting groundwater as a result of Potential for impacting groundwater as a result of
bridge piers
tunnel
5.3 Potential impacts to terrestrial features
Habit at potentially displaced or severed
Description
Assess the potential
effect s on terrestrial
features
Existing condition
Evaluation:
Potential for minor effects during construction but No impacts as the subway would be tunneled.
long term effects could be mitigated with an
appropriate revegetation/naturalization plan.
Enhancement opportunity
5.4 Potential impacts to fisheries and aquatic resources
Aquatic features potentially affected
Description
Assess the potential
effect s on aqautic
features
Existing condition
Evaluation:
SUMMARY:
York Region Rapid Transit Corporation
January 28, 2009
Potential for minor effects during construction but No impacts as the subway would be tunneled.
long term effects could be mitigated with a design
which spans the river.
Page 24
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Overall Summary
1.0 Social-Economic Considerations
1.1 Population+Employment density within station zone of influence
1.2 Major trip origins and destinations within station zone of influence
1.3 Potential to stimulate transit supportive development within station zone of influence
1.4 Effects on daily Yonge Street vehicular and pedestrian users
1.5 Potential impacts to residential and commercial properties
1.6 Potential effects on local noise, vibration, and air quality
1.7 Potential impacts to schools, places of worship, and unique community features
1.8 Achieve reasonable costs
1.9 Minimize potential cost associated with clean-up of potentially contaminated sites
Tunnel
Advantages:
- Has opportunity to create a gateway structure /
feature.
- Improves quality of pedestrian connection on
Yonge Street across the valley
- Improves visual connection with the valley when
valley naturalization is improved.
- Lower station cost
- On balance, potential disadvantages would be
outweighed by the advantages, after mitigation of
some negative effects is taken into account.
Advantages:
- Lower potential for effects associated with noise,
vibration, and air quality
- No changes to existing views or access to the
golf courses
- Lower construction cost than bridge
Disadvantages:
- Higher potential for noise, vibration, and air
quality effects as bridge is elevated and closer to
nearby residential properties. However, the
potential noise and vibration impacts can very
likely be successfully mitigated to MOE
guidelines, as described in the noise report,
through economically feasible mitigation
measures.
- Higher potential for construction-related impacts
to nearby residential properties
- Pedestrian experience on Yonge Street is on
bridge – limited opportunity for connectivity with
the valley
- Higher construction cost than tunnel
Disadvantages:
- No opportunities to restore river valley to natural
state
- Higher station cost
Advantages:
- Improves road profile of Yonge Street to benefit
of all traffic
- Higher user convenience due to shallow station
depth
Disadvantages:
- None
2.0 Transportation Opportunities
2.1
2.2
2.3
2.4
Bridge
Transit Network Connectivity
Associated Station Surface Facilities
Effects on Road Facilities
User Accessibility
York Region Rapid Transit Corporation
January 28, 2009
Advantages:
- None
Disadvantages:
- Lower user convenience due to deep station
depth
○
Page 25
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Overall Summary
Bridge
Advantages:
3.0 Technical / Constructibility
Advantages:
- No impact on Yonge Street traffic during
construction.
3.1 Compliance with design standards & criteria
3.2 Constructability
Disadvantages:
- Higher constructability impacts due to
traffic disruption on Yonge Street
○
Disadvantages:
Presence of bridge will have an effect to the
No significant effects on the cultural
character of the heritage district. A structure with a environment
heritage design is being considered.
4.0 Cultural Environment
4.1 Potential impacts to known archaeological sites
4.2 Effects on heritage features
4.3 Potential impacts to parks and recreation sites
5.0 Natural Environment
5.1 Potential impacts to Environmentally Sensitive Areas, Natural Heritage Systems, and Wildlife
Corridors
5.2 Potential impacts to surface water, identified water crossings, drainage features, and areas
susceptible to surface water contamination
5.3 Potential impacts to terrestrial features
5.4 Potential impacts to fisheries and aquatic resources
January 28, 2009
Advantages:
- Has opportunity for re-vegetation /
naturalization in the valley under the bridge
- Improves wildlife connection in the valley
Advantages:
- No impact to the valley - retains existing
conditions
Disadvantages:
- Short term construction-related disruptions
- Potential for impacting groundwater as a
result of bridge piers
Disadvantages:
- Potential for impacting groundwater as a
result of tunnel
- No opportunity to improve valley
naturalization
York Region Rapid Transit Corporation
Tunnel
Page 26
Yonge Subway Extension – Finch Station to Richmond Hill Centre
Conceptual Design and Functional Planning
Technical Report
East Don River Crossing Alternatives
EVALUATION OF EAST DON RIVER CROSSING ALTERNATIVES
Overall Summary
Bridge
Tunnel
○
CONCLUSION - Bridge Preferred
- Higher user convenience due to shallow station depth
- Has opportunity for re-vegetation / naturalization in the valley under the bridge
- Improves wildlife connection in the valley
- Improves road profile of Yonge Street
- Has opportunity to create a gateway structure / feature
- Improves quality of pedestrian connection on Yonge Street across the valley
- Lower station cost
- Opportunity to create a positive effect on cultural landscape subject to aesthetics of bridge design
○
Positive Effect
Neutral
Negative Effect
York Region Rapid Transit Corporation
January 28, 2009
Page 27