NCHRP 15-34A
Performance-Based Analysis of Geometric
Design of Highways and Streets
Kittelson & Associates, Inc.
University of Utah
January 2014
1
Presentation Outline
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Project Background and Overview
Information Gathering
Project Work Plan
NCHRP Report
2
Presentation Outline
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•
•
•
Project Background and Overview
Information Gathering
Project Work Plan
NCHRP Report
3
Project Background and Overview
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Past NCHRP 15-34
Transition to NCHRP 15-34A
Project Team
Project Goals
4
Project Background – NCHRP 15-34
• Past NCHRP 15-34
– The original intent of NCHRP project 15-34 was to facilitate the
transference of research findings and performance-prediction
technologies to application within highway and street decisionmaking processes.
• Transition to NCHRP 15-34A
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January 2007 Interim Report 1
February 2007 Project Panel Meeting
Fall 2007 Principal Investigator Change
2008/2009 Conduct Work
June 2009 Project Panel Meeting
March 2010 Project Stopped
Late Summer 2012 Project NCHRP 15-34A Initiated
5
Project Overview – NCHRP 15-34A
• Project Team
– Kittelson & Associates, Inc. – Brian Ray and Erin Ferguson
– University of Utah – RJ Porter
– Dr. John Mason
• Project Goals
– Review past material developed under NCHRP 15-34
– Develop NCHRP Report 15-34A
– Summarize research finding in the Supplemental Research
Materials Report
• Archived material, additional research details, AASHTO
Green Book revisions, and future suggested research
6
Presentation Outline
•
•
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Project Background and Overview
Information Gathering
Project Work Plan
NCHRP Report
7
Information Gathering
• Key Materials Obtained from NCHRP 15-34
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Original proposal
Original work plan
Phase I working files
First Interim Report
Framework Construction
Update on project activities
Draft of Second Interim Report
Kwon Final Thesis
Presentation files from TRB workshops
Panel comments to proposal and both interim reports
Panel Meeting notes from two panel meetings
8
Information Gathering
• Material to be archived
– Information primarily from NCHRP 15-34 First Interim
Report (January 2007)
• definitions and timing of design decisions
• recommended performance measures
• capabilities of performance prediction tools
• sensitivity of performance measures to geometric
design decisions
• NCHRP 15-34 archived material is located:
https://sites.google.com/site/nchrp1534archive/
9
Information Gathering
• Material used NCHRP Report 15-34A
– Similar project development process
• environmental clearance activities
– Tables and matrix summaries of design elements, design
decisions, and resources/software/tools available
• evaluate the performance effects of design decisions
– Updated performance categories
• consistent with broader, national performance-based
transportation decision making efforts
– Specific recommended performance measures
• capture panel priorities
• more recent completed research
10
Presentation Outline
•
•
•
•
Project Background and Overview
Information Gathering
Project Work Plan
NCHRP Report
11
Project Work Plan – Develop NCHRP Report 15-34A
• Deliverables
– Annotated Outline of the NCHRP Report 15-34A
– Draft Report documents
– Final Report documents
• NCHRP Report 15-34A
• Supplemental Research Materials Report
• Key Components
– Coordinate with the panel to receive input
– Consider past information gathered
– Incorporate new research material available
12
Presentation Outline
•
•
•
•
Project Background and Overview
Information Gathering
Project Work Plan
NCHRP Report
13
NCHRP 15-34A Report
• Part A: Basis and Knowledge for Performance Based
Analysis in Geometric Design of Highways and Streets
– Chapter 1 through 4 Overview
• Part B: Applications Guidance for Conducting
Performance Based Analysis
– Chapter 5 - Framework
– Chapter 6 - Project Examples
14
NCHRP 15-34A Report
• Part A
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Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
• Part B
– Chapter 5 – Process Framework
– Chapter 6 – Case Studies/Project Examples
15
NCHRP 15-34A Report
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Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
Chapter 5 – Process Framework
Chapter 6 – Case Studies/Project Examples
16
Chapter 1 - Introduction
• Role of performance-based analysis in transportation
activities
• Role and value in geometric design of highways and
streets
• Guiding Principles
– Intended outcomes
– Connect to project development process
– Performance measures of design decisions
17
Chapter 1 - Introduction
• Fundamental model of the approach
18
Chapter 1 - Introduction
• Performance-based analysis of geometric design
– principles-focused approach that looks at the outcomes of
design decisions as the primary measure of design
effectiveness.
• Identifying project intended outcomes
– basis for evaluating performance
• Geometric design performance
– Influences whether a project achieves intended outcomes
19
NCHRP 15-34A Report
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Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
Chapter 5 – Process Framework
Chapter 6 – Case Studies/Project Examples
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Chapter 2 – Overview
• Overview of geometric design decisions
21
Chapter 2 – Overview
• Relationship between project-level and performance
measures
22
Chapter 2 - Overview
• Geometric design and the project development
stages
– Planning Studies – not included
– Alternatives Identification and Evaluation
• Project initiation, purpose and need, traffic analyses,
preliminary alternatives, public outreach, technical
studies, cost/benefit evaluations, refined analyses,
selected alternative(s).
23
Chapter 2 - Overview
• Geometric design and the project development
stages - continued
– Preliminary Design
• Horizontal and vertical alignment, typical sections,
grading plans, structures, traffic/ITS, signing and
striping, illumination, and utilities.
– Final Design
– Construction
24
Chapter 2 – Overview
• Geometric design and environmental evaluations
and clearance
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Project Scoping
Purpose and Need
Alternatives Analysis
Effected Environment
Environmental
Consequences
– Mitigation
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NCHRP 15-34A Report
•
•
•
•
•
•
Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
Chapter 5 – Process Framework
Chapter 6 – Case Studies/Project Examples
26
Chapter 3 – Identify Project Outcomes
• Fundamentally: Who are we serving?
– Who are we serving?
• identifying the key road users and stakeholders for a
given project and project context
– What are we trying to achieve?
• identifying and articulating the core desired outcomes
from the project
27
Chapter 3 – Identify Project Outcomes
• Defining Project Performance – Goals and Measures
– US DOT’s Strategic Plan for
2012-2016
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•
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Economic competitiveness
Environmental sustainability
Livable communities
Organizational excellence
Safety
State of good repair
– Moving Ahead for Progress in
the 21st Century Act (MAP21)
•
•
•
•
Congestion Reduction
Infrastructure Condition
Environmental Sustainability
Freight Movement and
Economic Vitality
• Reduced Project Delivery
Delays
• Safety
• System Reliability
28
Chapter 3 – Identify Project Outcomes
• Geometric Design Performance Categories
– Accessibility
• ability to approach a desired destination or potential opportunity
for activity using highways and streets (including the sidewalks
and/or bicycle lanes).
– Mobility
• ability to move various users efficiently from one place to another
using highways and streets.
– Quality of Service
• the perceived quality of travel by a road user.
– Reliability
• consistency of performance over a series of time periods.
– Safety
• expected frequency and severity of crashes occurring on highways
and streets.
29
Chapter 3 – Identify Project Outcomes
• Role and Influence of Geometric Design Features
Defined Role/Influence of Geometric Design Features
Performance
Category
Well
Documented
Limited
Documentation
X
Accessibility
Mobility
Moderate
Documentation
X
X
Reliability
Safety
X
Quality of Service
X
30
Chapter 3 – Identify Project Outcomes
• Geometric Design Decisions
– consider overall intended project outcomes, project
performance, and transportation performance.
• How do the features or qualities of the features influence
performance measures related to accessibility, mobility,
quality of service, reliability, and safety?
– may have incremental and cumulative effects
– discrete choices may impact broader concepts
• sustainability, economic competitiveness, or livability
– identifying project design controls
• leads to appropriate design criteria to meet those design
control needs
31
Chapter 3 – Identify Project Outcomes
• Project Design Controls and Influences
– Speed concepts and design decisions
– Sight distance concepts
– Design choices for segments and nodes
32
Chapter 3 – Identify Project Outcomes
• Design choices for segments
Example Design Decisions for Segments

Access points and density

Shoulder type

Design speed and target speed

Lane and shoulder cross slopes

Horizontal alignment

Superelevation

Number of travel lanes

Roadside design features

Sidewalk and pedestrian facilities

Roadside barrier

Bicycle accommodation features

Minimum horizontal clearance

Transit accommodation features

Minimum sight distance

Design vehicle accommodation

Maximum grade

Median provisions

Minimum vertical clearance

Travel lane widths

Vertical alignment

Auxiliary lane widths

Bridge cross section

Type and location of auxiliary lanes

Bridge length/termini

Shoulder width

Rumble strips
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Chapter 3 – Identify Project Outcomes
• Design choices for nodes

Example Design Decisions for Nodes - Intersections and Interchanges
Intersection form, control type, and
features

Approach or ramp cross section


Horizontal alignment of approaches or ramp
Interchange form and features


Mainline ramp gores and terminals
Design speed and target speed


Cross road ramp terminals
Number and types of lanes


Vertical alignment of approaches or ramp
Sidewalk and pedestrian facilities


Auxiliary lane terminals and transitions
Bicycle accommodations facilities


Pavement cross slope and superelevation
Transit accommodations facilities


Intersection sight distance
Special/vulnerable user treatments


Median opening configuration
Design vehicle accommodations


Curve tapers & radii
Traffic islands


Ramp roadside
Lane widths


Ramp barriers
Auxiliary lane lengths

Shoulder width and composition
34
NCHRP 15-34A Report
•
•
•
•
•
•
Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
Chapter 5 – Process Framework
Chapter 6 – Case Studies/Project Examples
35
Chapter 4 – Geometric Design Elements
• Introduction
– Summarize critical or high priority known relationships
between design elements and performance
– Document the general relationship
– Identify possibly performance trade-offs
– Present resources and tools that can be used
36
Chapter 4 – Geometric Design Elements
• Overview
– Key Resources
• AASHTO’s Highway Safety Manual (HSM)
• 2010 Highway Capacity Manual (2010 HCM)
• Transit Capacity and Quality of Service Manual, 2nd
Edition (TCQSM)
• FHWA’s Speed Concepts: Informational Guide
• Draft 2010 HSM chapters for freeways and interchanges
(NCHRP Project 17-45)
• Interactive Highway Safety Design Model (IHSDM)
37
Chapter 4 – Geometric Design Elements
• Overview - Notations
– Each characteristic/decision – performance measure
category combination is classified as:
• Expected direct effect
• Expected indirect effect
• No expected effect
38
Chapter 4 – Geometric Design Elements
• Overview - Notations
– Secondary notation classifies each relationship as one of
the following :
• The relationship can be directly estimated by existing
performance prediction tools;
• The relationship can be indirectly estimated using more
than one existing tool or supplemental calculations;
• The relationship cannot be estimated by existing tools;
or
• Not applicable (i.e., the relationship does not exist).
39
Chapter 4 – Geometric Design Elements
• Expected relationships between geometric design
elements and performance categories
– Segments
– Nodes – Intersections and Interchanges
● = expected direct effect
□ = expected indirect effect
-- = expected not to have an effect
* = relationship can be directly estimated by existing performance prediction tools
◊ = relationship can be indirectly estimated using more than one existing tool
x = relationship cannot be estimated by existing tools
40
Chapter 4 – Geometric Design Elements
Segments
Segment Geometric
Elements/Characteristics
Access points and density
Design speed and target speed
Horizontal alignment
Number of travel lanes
Sidewalk and pedestrian facilities
Bicycle accommodation features
Median provisions
Travel lane width(s)
Auxiliary lane width(s)
Type and location of auxiliary lanes
Shoulder width(s) and composition
Shoulder type(s)
Lane & shoulder cross slopes
Superelevation
Roadside design features
Roadside barriers
Minimum horizontal clearances
Minimum sight distance
Maximum grade(s)
Minimum vertical clearances
Vertical alignment(s)
Bridge cross section
Bridge length/ termini
Rumble strips
Accessibility
Mobility
Quality of Service
Reliability
Safety
●*
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41
Chapter 4 – Geometric Design Elements
Nodes – Intersections
Intersection Geometric
Elements/Characteristics
Intersection form, control type, and
features
Number and types of lanes
Sidewalk and pedestrian facilities
Bicycle accommodation facilities
Design vehicle accommodations
Traffic islands
Lane widths
Auxiliary lane terminals and
transitions
Shoulder width and composition
Horizontal alignment of approaches
Vertical alignment of approaches
Pavement cross slope and
superelevation
Intersection sight distance
Median opening configuration
Curve tapers and radii
Accessibility
Mobility
Quality of
Service
Reliability
Safety
●◊
●*
●*
□x
●*
●◊
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42
Chapter 4 – Geometric Design Elements
Nodes – Interchanges
Interchange Geometric
Elements/Characteristics
Interchange form and features
Sidewalk and pedestrian
facilities
Bicycle accommodation facilities
Auxiliary lane lengths
Horizontal alignment of ramp
Vertical alignment or ramp
Pavement cross slope and
superelevation
Ramp cross section
Mainline ramp gores and
terminals
Ramp roadside
Ramp barriers
Cross road ramp terminals
Accessibility
Mobility
Quality of
Service
Reliability
Safety
●◊
●◊
●x
□x
●x
●x
●x
□x
●*
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43
Chapter 4 – Geometric Design Elements
• Geometric Design Decisions and Performance
– Accessibility
• ability to approach a desired destination or potential opportunity
for activity using highways and streets (including the sidewalks
and/or bicycle lanes).
– Mobility
• ability to move various users efficiently from one place to another
using highways and streets.
– Quality of Service
• the perceived quality of travel by a road user.
– Reliability
• consistency of performance over a series of time periods.
– Safety
• expected frequency and severity of crashes occurring on highways
and streets.
44
Chapter 4 – Geometric Design Elements
• Tables summarize the design elements/decisions and their
relationship to performance measures from each of the
transportation performance categories
• Key Resources
• AASHTO’s Highway Safety Manual (HSM)
• 2010 Highway Capacity Manual (2010 HCM)
• Transit Capacity and Quality of Service Manual, 2nd Edition
(TCQSM)
• FHWA’s Speed Concepts: Informational Guide
• Draft 2010 HSM chapters for freeways and interchanges (NCHRP
Project 17-45)
• Interactive Highway Safety Design Model (IHSDM)
• NCHRP Report 687, Guidelines for Ramp and Interchange Spacing
• NCHRP 672, Roundabouts: An Informational Guide, 2nd Edition
45
Chapter 4 – Geometric Design Elements
Accessibility
Facility Type
Performance
Measure
Definition
Geometric
Design
Elements
Basic Relationship
Segment
Driveway Density
Number of
driveways per mile
Access points
and density
Higher density of
driveways associated
with higher motor
vehicle access
Urban/
Suburban
Segment
Transit stop
spacing
Distance between
transit stops along
a roadway segment
Transit
accommodation
features
Higher frequency
increases access for
transit riders
Segment
Presence of
Pedestrian
Facility
Presence of a
sidewalk, multiuse
path or shoulder
Sidewalk and
pedestrian
facilities
Segment
Presence of
Bicycle Facility
Presence of bicycle
lanes, multiuse
path, or shoulder
Bicycle
accommodation
features
Greater connectivity
and continuity of
pedestrian network
increases access for
pedestrians
Greater connectivity
and continuity of
bicycle network
increases access for
bicyclists
Potential
Performance
Tradeoffs
Degrade bicycle LOS,
Increase crash likelihood,
Increase average travel
speed
Increases transit travel
time and may degrade
mobility for other vehicle
modes
Implementing pedestrian
facilities in a constrained
environment may require
removing capacity or
parking for vehicle mode
Implementing bicycle
facilities in a constrained
environment may require
removing capacity or
parking for vehicle mode
46
Chapter 4 – Geometric Design Elements
Mobility
Facility Type
Segment
Performance
Measure
Average Travel
Time
Definition
The mean amount of time
it takes a roader user to
travel from one point to
another point along a
roadway segment.
Geometric Design
Elements
Number of travel
lanes
Basic Relationship
Potential Performance
Tradeoffs
Degrades quality of
service for pedestrians
and bicyclists.
Increased vehicle lanes
decrease average travel Degrade mobility for
time for autos and
pedestrians and
increases vehicle speed.
bicyclists.
Higher vehicle speeds
are associated with
higher severity crashes.
Segment
Two-Lane
Segment
The maximum speed for
which all critical designInferred speed speed-related criteria are
met at a particular
location.
The average percent of
total travel time that
Average percent
vehicles must travel in
time spent
platoons behind slower
following
vehicles due to an
inability to pass.
Horizontal
Higher inferred speeds
Higher vehicle speeds
alignment, vertical associated with higher
are also associated with
alignment, and cross- free flow speeds and
higher severity crashes.
section
higher mobility.
Increased opportunities
Horizontal and
to pass slow moving
vertical alignment,
vehicles reduces percent
sight distance, Type
time spent following,
and location of
providing a passing lane
auxiliary lanes
can reduce crashes.
Increase vehicle
speeds, increase
potential for higher
severity crashes.
47
Chapter 4 – Geometric Design Elements
Mobility
Facility
Type
Performance
Measure
Freeway
Freeway
Segment
Speed
Delay
Intersection
Definition
Geometric Design
Elements
Potential Performance
Basic Relationship
Tradeoffs
Decreased freeway speeds
Ramp spacing
The freeway speed
are possible with
down stream of an dimensions as defined At relatively high exit
entrance ramp and in NCHRP Report 687.
ramp volumes, ramp decreased ramp spacing.
before an exit ramp or
spacing affects freeway
speeds
another entrance
Use of downstream
An auxiliary lane may
ramp
auxiliary lane
improve freeway speeds
Average control delay
Intersection form,
experienced by road
control type, and
users at an
features, Number and
intersection.
types of lanes
Often tradeoffs between
delay experienced by
Lower control delay for
different modes
any road user improves
mobility for that mode depending on the type of
traffic control present
.
Volume to
Capacity (v/c)
Ratio
Degrades quality of
The ratio of volume
Intersection form,
service
for pedestrians
present or forecasted
Increased vehicle
control type, and
and bicyclists.
and the available
capacity associated with
features, Number and
lower v/c ratios.
capacity at the
Degrade mobility for
types of lanes
intersection.
pedestrians and bicyclists.
48
Chapter 4 – Geometric Design Elements
Quality of Service
Facility Type
Performance
Measure
Definition
Geometric Design
Elements
Basic Relationship
Potential
Performance
Tradeoffs
Increasing width of
A letter grade
Sidewalk and
pedestrian facility,
Meeting performance
associated with the pedestrian facilities,
increasing distance from metrics for pedestrians
quality of travel
width of pedestrian
Urban/ Suburban
vehicle traffic, decreasing
may degrade travel
Pedestrian LOS
experience for a
lanes, buffer from
Segment
driveway density, and quality for other modes –
pedestrian. Based on
vehicle traffic,
increasing opportunities
e.g., on-street parking
HCM 2010
driveway density,
to cross a street improves improves pedestrian LOS
methodology.
crossing frequency
pedestrian LOS
and degrades bicycle LOS
A letter grade
associated with the
Urban/ Suburban
quality of travel
Pedestrian LOS
Intersections
experience for a
pedestrian. Based on
HCM 2010
methodology.
Crossing distance,
traffic control delay
Decreasing pedestrian
crossing distance and
delay to cross a street
improves pedestrian LOS
Meeting performance
metrics for pedestrians
may degrade travel
quality for other modes
49
Chapter 4 – Geometric Design Elements
Quality of Service
Facility Type
Urban/
Suburban
Segment
Urban/
Suburban
Intersections
Performance
Measure
Bicycle LOS
Bicycle LOS
Definition
Geometric Design
Elements
Basic Relationship
Potential
Performance
Tradeoffs
Increasing width of
Bicycle
A letter grade
bicycle facility,
accommodation
Meeting
associated with the
decreasing driveway
features, physical
performance metrics
quality of travel
density, increasing
separation from
for bicyclists may
experience for a
separation from moving
motor vehicle traffic,
degrade travel
bicyclist. Based on
vehicle traffic, and
access points and
quality for other
HCM 2010
removing on-street
modes
density, on street
methodology.
parking improves bicycle
parking
LOS
A letter grade
associated with the
quality of travel
experience for a
bicyclist. Based on
HCM 2010
methodology.
Traffic control delay
Decreased delay for
bicyclists increases
quality of travel
experience
Meeting
performance metrics
for bicyclists may
degrade travel
quality for other
modes
50
Chapter 4 – Geometric Design Elements
Quality of Service
Facility Type
Urban/
Suburban
Segments and
Intersections
Urban/
Suburban
Segments and
Intersections
Intersections
and Segments
Performance
Measure
Transit LOS
Auto LOS
Large Vehicle
Turning and OffTracking
Characteristics
Definition
Geometric Design
Elements
A letter grade
Transit
associated with the
accommodations
quality of travel
facilities (presence of
experience for a
transit only lane, bus
transit rider. Based
pull out areas, bus
on HCM 2010
merge/diverge lanes,
methodology.
bus queue jump
lanes)
Number and
Number of travel
duration of stops
lanes, intersection
along an
form, control type,
urban/suburban
and features
corridor.
Ability and ease
with which large
vehicles are able to
Curve radii, curb
physically move
radii, lane width
through an
intersection or
along a segment
Basic Relationship
Potential
Performance
Tradeoffs
Providing bus only lane, Incorporating transit
queue jump lanes,
only features often
merge/diverge lanes
comes at the
decreases bus travel
expense of providing
time and improves
additional auto or
transit rider quality of
bicycle capacity or
travel
treatments
Reducing the number of
Increased vehicle
stops and duration of
lanes and speeds
stops along a corridor degrades pedestrian
improves auto MMLOS and bicycle MMLOS
Increasing curve
Generally larger curve radii, curb radii, and
radii, larger curb radii
lane width often
and wider vehicle lanes degrade pedestrian
enable easier navigation and bicycle MMLOS
for larger vehicles
due to the longer
crossing distances
51
Chapter 4 – Geometric Design Elements
Reliability
• On-going research to develop performance measures to
connect reliability to specific geometric design elements
• Variation in travel time and variation in speed are two
more common performance measures
• There are no clear performance measures available to
easily integrate into design decision
• Additional reliability resources:
– SHRP 2 L07: Evaluation of Cost-Effectiveness of Highway Design
Features (9)
– SHRP 2 L08: Incorporation of Travel Time Reliability into the
Highway Capacity Manual (10)
– SHRP 2 L09: Incorporation of Non-recurrent Congestion Factors
into the AASHTO Policy on Geometric Design (11)
52
Chapter 4 – Geometric Design Elements
Reliability
• There are a number of design considerations that can be applied to
highways and streets. These include the following tradeoffs:
– Mobility gained in implementing peak period hard shoulder running on a
freeway segments and risk associated with a disabled vehicle during the
peak period.
– Congestion pricing strategies on freeway segments to improve reliability
and potential equity implications for lower income households.
– Ramp metering strategies to preserve the quality of mainline traffic flow
while at the expense of degrading mobility on adjacent local streets.
– Implementing transit signal priority, bus only lane and/or queue jumps for
transit vehicles along an urban corridor to improve the reliability of bus
service with the potential impact of degrading mobility for side street
vehicle traffic.
– Implementing concrete median barriers with heights that eliminate
distractions from incidents on opposing roadway lanes (“rubbernecking”)
and the potential safety performance degradation by introducing a fixed
object.
53
Chapter 4 – Geometric Design Elements
Safety
Facility Type
Performance
Measure
Definition
Rural two-lane
segments
Rural two-lane
intersection
Rural multilane
segments
Rural multilane
intersection
Crash frequency
and severity
Expected
number of and
severity of
crashes
Basic
Geometric Design Elements Relationship
Horizontal alignment, shoulder
width and composition, shoulder
type, lane width, type and
location of auxiliary lanes, rumble
strips, roadside design features,
lighting, two-way left turn lane,
grade
Intersection form, control type,
and features, number and types
of lanes, lighting, skew
Shoulder width and composition,
shoulder type, lane width, lane
and shoulder cross slopes,
median provisions, lighting, twoway left turn lane
Intersection form, control type,
and features, number and types
of lanes, lighting, skew
Potential
Performance
Tradeoffs
See HSM
See HSM
See HSM
Some safety
improvements
reduce mobility,
reduce access (e.g.,
reducing driveway
density), or
negatively impact
another
performance
measure.
See HSM
54
Chapter 4 – Geometric Design Elements
Safety
Facility Type
Performance
Measure
Urban/suburban
segments
Urban/suburban
intersection
Crash frequency
and severity
Freeway Segments
Interchange
Definition
Geometric Design
Elements
Basic
Relationship
Potential
Performance
Tradeoffs
Basic cross-section, ,
access points and density,
See HSM
fixed object density,
median provisions, onstreet parking
Intersection form, control
Some safety
type, and features,
improvements
See HSM
number and types of
reduce mobility,
lanes, signal phasing
reduce access
Expected number of
Lane width, shoulder
(e.g., reducing
and severity of
width and composition,
driveway density),
crashes
ramp spacing, use of
See NCHRP Report
or negatively
17-45
auxiliary lanes, ramp
impact another
entrance/exit
performance
configurations
measure.
Interchange form and
features, number and
See NCHRP Report
types of lanes, horizontal
17-45
alignment, cross section,
roadside
55
Chapter 4 – Geometric Design Elements
• Opportunities to Expand Performance-Based Analysis
– A key fundamental concept in performance-based analysis to inform design
decisions is geometric sensitivity.
– Geometric sensitivity
• The degree to which varying the dimensions related to a geometric element
has an impact on performance.
• A relationship that shows an expected impact on some aspect of
transportation performance as a direct result of a geometric design decision.
– Level of sensitivity
• amount of the impact
• highly sensitive
– number of travel lanes versus passenger car mobility
• less sensitive
– lane width and average travel speed
• Certain relationships are sensitive only for certain ranges of geometric
dimensions.
56
Chapter 4 – Geometric Design Elements
• Opportunities to Expand Performance-Based Analysis
– NCHRP Report 687, Guidelines for Ramp and Interchange
Spacing
57
NCHRP 15-34A Report
•
•
•
•
•
•
Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
Chapter 5 – Process Framework
Chapter 6 – Case Studies/Project Examples
58
Chapter 5 – Process Framework
59
Chapter 5 – Process Framework
• Project Initiation
– Project Context
• existing site constraints
• current performance
• surrounding land uses
• planned improvements
• anticipated form and function
– Intended Outcomes
• Clarity of the characteristics defining the current and desired
future of the site;
• A clear and concise understanding of the primary project
purpose; and
• A set of performance measures to be used to evaluate a
design’s impact on the desired project purpose.
60
Chapter 5 – Process Framework
• Concept Development
– Geometric Influences
• Identify the geometric characteristics that influence a
project’s performance
• Identify the geometric characteristics or decisions
influenced by the desired performance of a project.
– Potential Solutions –
specific awareness of the:
• Project context
• Intended outcomes
• Geometric characteristics and
decisions
61
Chapter 5 – Process Framework
• Evaluation and Selection
– Estimated Project Performance
• Selecting the evaluation resource
– For the stage in the project
development process.
– Applicable to the project context
– Financial Feasibility
• Total construction and
maintenance cost
• Cost effectiveness
• Benefit/cost Ratio (B/C ratio)
– Interpreting Results
• Estimated Project Performance
• Financial Feasibility
62
Chapter 5 – Process Framework
• Selection
– Are the performance evaluation results
making progress towards the intended
project outcomes?
– Do the alternatives serve the target
audience and achieve the desired
objectives?
– Are there reasonable adjustments that can be made to
the geometric design elements most significantly
influencing project performance?
– Do the performance measures help differentiate
between the alternatives?
63
Chapter 5 – Process Framework
• Environmental Review Process
– Environmental Checklist
• The 15-34A framework can be used to explore and consider project
alternatives or adjustments to enable a project to be eligible for a
Categorical Exclusion.
– Environmental Assessment
• Project Initiation phase of the performance-based analysis framework
can serve as a useful resource in developing a clear, sound, and concise
project Purpose and Need statement.
• Concept Development and Evaluation and Selection phases of the
framework are resources for developing alternatives that minimize the
potential for environmental impacts.
– Environmental Impact Statement
• The 15-34A framework can be beneficial to practitioners in developing a
draft EIS, selecting a preferred alternative in the final EIS, and
identifying the means to avoid and minimize environmental impacts.
64
NCHRP 15-34A Report
•
•
•
•
•
•
Chapter 1 – Introduction
Chapter 2 – Overview
Chapter 3 – Identify Project Outcomes
Chapter 4 – Geometric Design Elements
Chapter 5 – Process Framework
Chapter 6 – Case Studies/Project Examples
65
Chapter 6 – Case Studies/Project Examples
• Case Studies include a
range of projects for:
–
–
–
–
Site - Area and Facility Type;
Project Development Stage;
Performance Categories, and
Project Type.
66
Chapter 6 – Case Studies/Project Examples
Case
Study #
Site - Area and
Facility Type
Project
Development Stage
1
US 21/Sanderson Road - Alternatives
Rural Collector (Two-Lane Identification and
Highway)
Evaluation
2
Richter Pass Road - Rural
Collector
3
Cascade Ave Suburban/Urban Arterial
4
5
6
SR 4 - Rural Collector
Safety
Preliminary Design
Safety, Mobility
Preliminary Design
Safety, Mobility,
Reliability,
Accessibility, Quality
of Service
Preliminary Design
Safety, Reliability,
Quality of Service
Avenue - Urban
Minor Arterial
Alternatives
Identification and
Evaluation
US 6/Stonebrook Road Rural Interchange
Alternatives
Identification and
Evaluation
27th
Performance
Categories
Project Type
Intersection – Consider alternative
intersection control to improve safety.
Segment – Consider alternative horizontal
curve radii to improve safety while
minimizing costs and maintaining
appropriate speed.
Corridor – Retrofitting an existing autooriented urban arterial to incorporate
complete street attributes. Focus on
alternative street cross-sections.
Segment – Consider alternative shoulder
widths and sideslopes to minimize impact
to an environmentally sensitive area.
Segment – Alignment and cross-section
Quality of Service, considerations for new urban minor arterial
Safety, Accessibility being constructed to entice employers to a
newly zoned industrial area.
Safety, Mobility
Interchange - Converting an at-grade
intersection to a grade-separated
interchange. Focus on selecting the
appropriate interchange form and location
67
Case Study #1 – US 21/Sanderson Road
• Alternatives identification and evaluation stage of an
intersection project
• Rural two lane highway (i.e., rural arterial)
• Intended outcome - improve safety
• Performance category – safety
– uses expected crash frequency as the primary performance
metric
• The learning objectives of this case study include:
– Illustrating the process of applying performance-based analysis;
– Demonstrating the use of resources beyond typical design
manuals within the project development process; and
– Illustrating how a financial feasibility assessment can inform
project selection.
68
Case Study #1 – US 21/Sanderson Road
Project Initiation - Project Context
•
Intersection Characteristics
– Rural, two-lane highway (US 21)
– Two-way stop controlled intersection
– Primary entrance to a tribal reservation
•
US 21 Highway - Regional east-west connection
–
–
–
–
–
•
Agricultural, undeveloped, wetlands, and low density residential
AADT is approximately 7700 vehicles per day
Posted speed is 55 mph, the 85th percentile speed is 58 mph
Limited to no pedestrian or bicycle activity
Intersection operational level of service (LOS) is LOS B
Safety Data – Several fatal and serious injury crashes - Past 5 years
• 55% were angle or turning crashes
• 26% were rear-end crashes
• Failure to yield right-of-way (26% of crashes) and excessive
speed (16% of crashes)
• Incremental solutions
– adding illumination
– Adding left-turn and right-turn lanes on US 21.
69
Case Study #1 – US 21/Sanderson Road
Project Initiation - Intended Outcomes
• Tribe and the State Department of
Transportation (DOT)
– Initiated a study to identify additional safety
projects
• Reduce the number and severity of
crashes
• Enhance the intersection as the gateway
to their community
• Accommodate a full range of motorists –
agricultural equipment, logging trucks,
local residents and visitors.
• Performance category - safety
70
Case Study #1 – US 21/Sanderson Road
Concept Development
• Design elements related to crash frequency/severity
Performance Target
Related Design Elements
Intersection Control
Reduce Total Number of Crashes;
Reduce Severity of Crashes
Intersection Design Features
Increase Intersection
Awareness/Visibility
Decrease Vehicle Speed on
Intersection Approach
Related Design Considerations
Two-way stop controlled
All-way stop controlled
Traffic Signal
Roundabout
Left-Turn Lanes
Right-Turn Lanes
Presence of Lighting
Visibility of Intersection
Cross-Sectional Elements on
Intersection Approach
Lane Width
Rumble Strips
Median (Painted or Splitter Island Type)
Cross-Sectional Elements on
Intersection Approach
Lane Width
Rumble Strips
Median (Painted or Splitter Island Type)
Alignment on Intersection
Approach
Roadway curvature
Sight Distance
Advanced Signing
71
Case Study #1 – US 21/Sanderson Road
Concept Development
• The project team identified the
following groupings of
alternatives to explore:
– Alternative intersection control;
– Advanced signing and pavement
markings; and
– Changes in roadway crosssectional features.
72
Case Study #1 – US 21/Sanderson Road
Potential Solutions
• Potential intersection configurations - to
make the intersection more visible and
more clearly identifiable as the main
intersection to access the tribal land.
–
–
–
–
Implementing lane narrowing
Constructing a Single-Lane Roundabout;
Installing a Traffic Signal
Way-finding signs and landscaping
• Resources Used
– AASHTO Green Book
– NCHRP Report 672 Roundabouts: An Informational Guide, Second Edition
– FHWA’s Low Cost Safety Concepts for Two-Way Stop Controlled, Rural
Intersections on High-Speed Two-Lane, Two-Way Roadways
– NCHRP Report 613 Guidelines for the Selection of Speed Reduction Treatments
on High-Speed Intersections
73
Case Study #1 – US 21/Sanderson Road
Potential Solutions
• Solution Development – Single Lane Roundabout
74
Case Study #1 – US 21/Sanderson Road
Potential Solutions
• Design Decisions – Single Lane Roundabout
– Appropriate size
• posted speed on US 21
• design vehicles
• anticipated turning movement volumes
– Number of entry and exit lanes on each approach
• anticipated turning movement volumes
– Entry and exit curve radii
• design vehicles
• estimated entry, circulating and exiting vehicle speeds
– Appropriate length of the splitter islands on US 21 to help make the
intersection visible and support appropriate speed reduction from the
roadway segment to the roundabout entry.
• Resource - NCHRP Report 672 Roundabout Informational Guide,
Second Edition
75
Case Study #1 – US 21/Sanderson Road
Potential Solutions
• Solution Development – Traffic Signal
76
Case Study #1 – US 21/Sanderson Road
Potential Solutions
• Design Decisions – Traffic Signal
– Appropriate length of the approach medians on US 21 to
help make the intersection visible
– Number of lanes and lane arrangement based on
anticipated turning movement volumes
– Appropriate curve radii based on design vehicles
– Appropriate taper lengths and deceleration lane lengths
based on posted speed
77
Case Study #1 – US 21/Sanderson Road
Evaluation and Selection
• Primary intent of the project
– reduce the frequency and severity
of crashes
• Secondary consideration
– incorporate way-finding and
gateway treatments at the
intersection
• Performance evaluation and
financial feasibility
– evaluating safety effectiveness as
related to the likelihood of reducing
crash frequency and severity
78
Case Study #1 – US 21/Sanderson Road
Evaluation and Selection
• Estimating Performance
– Design Elements Related to Crash Frequency/Severity
Performance Target
Related Design
Elements
Related Design
Considerations
Two-way stop controlled
All-way stop controlled
Intersection Control
Traffic Signal
Tools or Resources to Evaluate Performance
Highway Safety Manual, Chapter 10 and Chapter
14 (5)
Supporting Software Tools: HiSafe; IHSDM
Roundabout
Reduce Total Number of
Crashes; Reduce
Severity of Crashes
Left-Turn Lanes
Intersection Design
Features
Right-Turn Lanes
Presence of Lighting
Visibility of Intersections
Highway Safety Manual, Chapter 10 and Chapter
14 (5)
Supporting Software Tools: HiSafe; IHSDM
FHWA’s Low Cost Safety Concepts for Two-Way
Stop Controlled, Rural Intersections on HighSpeed Two-Lane, Two-Way Roadways (3)
NCHRP Report 613 (4)
79
Case Study #1 – US 21/Sanderson Road
Evaluation and Selection
• Estimating Performance
– Design Elements Related to Crash Frequency/Severity
Performance Target
Increase Intersection
Awareness/Visibility
Decrease Vehicle
Speed on
Intersection
Approach
Related Design
Elements
Cross-Sectional
Elements
Cross-Sectional
Elements on
Intersection Approach
Related Design
Considerations
Lane Width
Rumble Strips
Median (Painted or Splitter
Island Type)
Lane Width
Rumble Strips
Median (Painted or Splitter
Island Type)
FHWA’s Low Cost Safety Concepts for Two-Way
Stop Controlled, Rural Intersections on HighSpeed Two-Lane, Two-Way Roadways (3)
NCHRP Report 613 (4)
FHWA’s Low Cost Safety Concepts for Two-Way
Stop Controlled, Rural Intersections on HighSpeed Two-Lane, Two-Way Roadways (3)
NCHRP Report 613 (4)
Sight Distance
FHWA’s Low Cost Safety Concepts for Two-Way
Stop Controlled, Rural Intersections on HighSpeed Two-Lane, Two-Way Roadways (3)
Advanced Signing
NCHRP Report 613 (4)
Roadway curvature
Alignment on
Intersection Approach
Tools or Resources to Evaluate Performance
80
Case Study #1 – US 21/Sanderson Road
Evaluation and Selection
• Incorporating Financial Feasibility
– identify the relative cost effectiveness of each alternative
Expected
Crashes/ Year
Estimated
Percent
Reduction
# of Crashes
Mitigated/Y
ear
Design
Life
(Years)
Planning
Level Cost
Estimate
$/Crash
Mitigated
Over Design
Life
2.2
31%
0.7
5
$45,000
$13,196
Sanderson Road
Intersection TWSC FHWA Splitter Island
2.2
68%
1.5
5
$112,500
$15,040
Sanderson RoadSingle Lane
Roundabout
2.2
71%
1.6
20
$3.15 million
$100,832
Sanderson Road Traffic Signal
2.2
36%
0.8
20
$5.61 million
$354,167
Location - Solution
Sanderson Road
Intersection TWSCFHWA Lane Narrowing
81
Case Study #1 – US 21/Sanderson Road
Selected Alternative
• Tribe and DOT decided to
implement a roundabout at the US
21/Sanderson Road intersection
– way-finding and gateway treatments
• Roundabout Alternative
– Long-term potential for reducing the
intersection crash frequency and
severity
– Opportunities for gateway treatments
at and on approach to the intersection
– Create definitive visual cues and
changes in roadway geometry to
capture motorists’ attention and aid in
reducing approach speeds.
82
Case Study #3 – Cascade Avenue
• Reconstructing an existing auto-oriented urban arterial
– complete street attributes
– alternative street cross-sections
• Local business owners would like to see the corridor revitalized
• The learning objectives of this case study include:
– Incorporating performance measures and decisions related to
accommodating multiple modes;
– Illustrating tradeoffs between modes considering measures beyond
mobility; and
– Capturing considerations and tradeoffs within a constrained physical
environment.
• Geometric design performance categories of quality of service
for multiple modes, safety, access, reliability and mobility.
83
Case Study #3 – Cascade Avenue
Project Initiation - Project Context
• Cascade Avenue
– Urban arterial
– North-south connection between the downtown
and university
– AADT volume 22,000 vehicles per day
– Three different fixed transit routes - 45% of
riders within the City
– Frequently used by bicyclists
– Posted speed on Cascade Avenue is 35 mph
84
Case Study #3 – Cascade Avenue
Intended Outcomes
• Target audience
– Business community stakeholders
– Transit riders, pedestrians and bicyclists
– Local residents and existing motorists
• Intent of the Study
– Improve the road user experience
– Provide access to road users not previously served
– Enhance the economic vitality and activity of the street
• Performance categories
– quality of service, safety, accessibility, reliability, and
mobility
• Performance measures
– Quality of Service – Multimodal Level of Service (MMLOS)
– Safety – Crash frequency and conflict points
– Accessibility – Type and presence of facilities and transit
service characteristics
– Mobility – Average travel time
– Reliability – Consistency in travel time
85
Case Study #3 – Cascade Avenue
Concept Development
• Roadway cross-sectional elements
were selected as the primary
geometric elements likely to influence
the performance measures
–
–
–
–
–
Lane width
Number of automobile through lanes
Bicycle facility presence and type
Sidewalk width
Landscaped buffer between sidewalk and
travel lanes
– On street parking
– Bus only lanes
– Central roadway median
86
Case Study #3 – Cascade Avenue
Potential Solutions
• The four basic alternatives :
– Alternative 1 – Existing cross-section oriented towards serving automobiles
• Baseline for comparison
– Alternative 2 – Transit oriented cross-section
• Serve transit vehicles and riders
– Alternative 3 – Bicycle and pedestrian oriented cross-section
• Serve bicyclists and pedestrians
– Alternative 4 – Hybrid of transit, bicycle and pedestrian features.
• Serve transit, bicyclists and pedestrians
• Resources Used to Develop Solutions
– Urban Streets Design Guide published by the National Association of City
Transportation Officials (NACTO)
– NACTO’s Urban Bikeway Design Guide
– AASHTO Guide for the Development of Bicycle Facilities, 4th Edition
– City’s local design guides and standards
87
Case Study #3 – Cascade Avenue
Potential Solutions – Solution Development
• Each alternative cross-section has a modal emphasis in contrast to the
existing auto-oriented cross-section
• A common element among the alternatives is the lack of on-street
parking.
– More pedestrian space
– City’s goals and policies focus on projects serving person-trips rather than only
auto trips
– Creates concern for on-street parking in adjacent residential areas
• Other tradeoffs considered
– allocating lanes for specific modes – Transit-only lane
• improve mobility and reliability for transit riders
• more predictable operating conditions
• negatively impacts mobility (and potentially reliability) for automobiles
– Providing bicycle lanes and wider sidewalks for pedestrians
• Alternatives include a central landscaped median
– documented safety benefits for autos and pedestrians
– Space to implement landscaping to help improve the aesthetics of the corridor
88
Case Study #3 – Cascade Avenue
Potential Solutions – Primary Alternative Evaluation
89
Case Study #3 – Cascade Avenue
Potential Solutions – Primary Alternative Evaluation
90
Case Study #3 – Cascade Avenue
Potential Solutions – Primary Alternative Evaluation
•
Common elements across the alternatives
– Falls within the existing 82 feet of right-of-way width
• no additional right-of-way required
– Requires changing the existing curb locations
• revised storm water management and drainage along the corridor
– Reduces the capacity for automobiles
• Two-lanes in each direction to one-lane in each direction
– Removes on-street parking
– Increases sidewalk width for pedestrians
•
Differentiating factors across the alternatives
–
–
–
–
•
Amount of space designated for bicyclists
Presence of a central median
Presence of a physical buffer for pedestrians and bicyclists from motor vehicles
Type of space allocated for transit vehicles
Additional critical considerations
– Logistics of truck loading and unloading for the businesses
– Defining transition areas on approach to intersections or major driveways
• Manage conflict areas within transit-only and/or bicycle lanes
– Traffic control and lane configurations at intersections
91
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Performance categories
– Safety
• crash frequency, crash severity,
and conflict points
– Mobility
• average travel time
– Reliability
• Variation in travel time
– Accessibility
• Type and facility presence and
transit service characteristics
– Quality of service
• multimodal level of service
92
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Estimating Performance
– Summary of Resources
Alternative
Quality of
Service
Safety
Mobility
Reliability
Accessibility
#1 – Existing Condition
HSM, Chapter 12
HCM 2010
HCM 2010
Qualitative
Assessment
HCM 2010
#2 – Transit Oriented
HSM, Chapter 12
Principles
HCM 2010
HCM 2010
Qualitative
Assessment
HCM 2010
#3 – Bicycle and Pedestrian
Oriented
HSM, Chapter 12
Principles
HCM 2010
HCM 2010
Qualitative
Assessment
HCM 2010
#4 – Hybrid of Transit, Bicycle
and Pedestrian
HSM, Chapter 12
Principles
HCM 2010
HCM 2010
Qualitative
Assessment
HCM 2010
93
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Estimating Performance – Safety
– AASHTO’s HSM methodologies
– Safety performance for urban/suburban arterials roadway crosssections
• Cross-sections ranging from two-lane undivided to five-lanes
– Estimate the long-term annual safety performance of Cascade
Avenue if no changes to the cross-section were made.
– Remaining features that cannot be evaluated using the HSM
• The transit lanes present in Alternative 2 and 4;
• The buffered bicycle lane present in Alternative 3; and
• The traditional bicycle lane in Alternative 4.
Qualitative considerations based on the alternative’s ability to
separate conflicting modes and provide protected space for
vulnerable users.
94
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Estimating Performance – Mobility
– Highway Capacity Manual (HCM) 2010 methodologies
• Average travel time from one end of Cascade Avenue to
the other.
– morning, mid-day and evening weekday periods
– Saturday mid-day peak period.
• Travel time for motorists and transit vehicles
95
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Estimating Performance – Reliability
– On-going research to develop performance measures and
a means to strengthen the connection between reliability
and geometric design decisions
– Current approach for urban arterials
• Variation in travel time is the best means for estimating
relative consistency for motorists and transit riders on
Cascade Avenue
• Simulated traffic operations along the corridor
96
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Estimating Performance – Accessibility
– Qualitative assessment of access
• low, moderate, or high
• presence of facilities for specific modes and the transit
service characteristics reflected in each alternative.
97
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Estimating Performance – Quality of Service
– Multimodal Level of Service (MMLOS) - HCM 2010
• Provides a letter grade A through F to indicate the
quality of the travel experience from specific road
users’ perspective.
• May result in one street cross-section having different
quality of experiences depending on whether a person
is walking, biking, taking transit or driving an
automobile.
• Captures some of the benefits from project elements
the HSM cannot; such as bicycle lanes.
98
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Performance Evaluation Results
Mobility: Average
Travel Time (min)
Reliability:
Variation in
Travel Time
Accessibility
Quality of
Service:
MMLOS
4.43
2.67
3.68 to 5.26
2.42 to 3.17
Low
Low
Moderate
High
D
F
D
A
4.40
3.43
3.68 to 4.76
3.35 to 3.60
Moderate
Moderate
High
Low
C
E
B
C
4.80
4.80
3.97 to 6.00
3.80 to 6.10
High
High
Moderate
Low
B
C
D
D
4.38
3.45
3.65 to 4.78
3.32 to 3.56
Moderate
Moderate
High
Low
C
D
B
C
Alternative
Safety
#1 – Existing Condition
Pedestrian
Low
Bicycle
Low
Transit
Low
Auto
Low
#2 – Transit Oriented
Pedestrian
High
Bicycle
Moderate
Transit
High
Auto
High
#3 – Bicycle and Pedestrian Oriented
Pedestrian
High
Bicycle
High
Transit
High
Auto
High
#4 – Hybrid of Transit, Bicycle and Pedestrian
Pedestrian
Low
Bicycle
Moderate
Transit
Moderate
Auto
Low
99
Case Study #3 – Cascade Avenue
Evaluation and Selection
• Incorporating Financial Feasibility
– identify the relative cost effectiveness of each alternative
Alternative
Alternative #1 – Existing Condition
Cost per Mile
$0
Alternative #2 – Transit Oriented
$1.4 million
Alternative #3 – Bicycle and Pedestrian Oriented
$1.6 million
Alternative #4 – Hybrid of Transit, Bicycle and Pedestrian
$1.0 million
100
Case Study #3 – Cascade Avenue
Selected Alternative
• City and project stakeholders - Alternative 2
– provides improved safety, reliability, access, and quality of service for
transit riders, pedestrians and bicyclists.
• Local business community - Alternative 3
– City plans to integrate Alternative 3 attributes into Alternative 2
• landscaping along the sidewalks
• characteristics to better serve bicyclists
101
NCHRP 15-34A Report
Summary
• Performance-based analysis of geometric design
– principles-focused approach that looks at the outcomes of
design decisions as the primary measure of design
effectiveness.
• Geometric Design Performance Categories
– Accessibility, Mobility, Quality of Service, Reliability, Safety
• Process Framework
–
–
–
–
Project Initiation – Project Context and Intended Outcomes
Concept Development – Geometric Influences and Potential Solutions
Evaluation – Estimated Performance and Financial Feasibility
Selected Alternative
102
Presentation Outline
•
•
•
•
Project Background and Overview
Information Gathering
Project Work Plan
NCHRP Report
103
NCHRP 15-34A: Performance-Based Analysis of
Geometric Design of Highways and Streets
Questions?
Brian Ray bray@kittelson.com
Erin Ferguson
eferguson@kittelson.com
Richard J. Porter richard.jon.porter@utah.edu
104