TUE LEHN-SCHIØLER
SENIOR CONSULTANT, PH.D.
ESTIMATING THE EFFICIENCY OF
A WATERWAY
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FEMERN BELT
FIXED LINK
20 Km fixed link connecting
Denmark and Germany
Construction scheduled
2015-2020
The link crosses the heavy
trafficked Femern Belt - the
entrance to the Baltic sea
Our focus:
Navigational safety
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FEMERN BELT TRAFFIC
Route traffic 2010 (per year):
40,000 Ships
10,000 Tankers
Other traffic 2010
20,000 Ferries
2,000 Fishing
4,000 Pleasure crafts
Prediction for 2030:
90,000 Ships
16,000 Tankers
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FEMERN BELT AIS MOVIE
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FEMERN BELT FIXED LINK
Bridge (preferred alternative)
Tunnel (preferred solution)
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FEMERN BELT FIXED LINK
Bridge
Tunnel
Navigational safety during
construction and permanent
phase
Navigational safety during
construction phase
Determine necessary bridge
span and width of TSS
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NAVIGATIONAL SAFETY
Traffic analysis
• AIS, radar data, accident registrations, interviews
• Traffic forecast
• Ship counts, size, speed and type distributions
• Ship behaviour near boring rigs
Risk assessment (safety)
• Collision models
• Risk mitigation (effect of VTS, guard ships, TSS)
• Environmental impact, oil spill
Construction phase
Permanent phase
Bridge and tunnel
Traffic flow assessment (efficiency)
• Navigator comfort
• Construct TSS
• Safety ellipsis, free flow
Real Time simulations
Permanent phase
Bridge
• Markings
• Layout feasibillity
• (Safety)
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SAFETY AND EFFICIENCY
A “small” bridge span may be safe as navigators can navigate
safely in narrow straits and in harbours
With a small bridge span navigators will need to reduce speed and
take extra precautions - some ships may be delayed
Safety:
Will the bridge cause accidents?
(Tools: Iwrap, PAWSA, ShipRisk, ...)
Efficiency: Will the bridge be a hindering to the traffic flow?
(Tools: ? )
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FREE FLOW: A DESIGN TOOL FOR
DETERMINING THE NECESSARY BRIDGE SPAN
Free flow
Required elements
Ships sailing with sufficient
distance to other ships or fixed
objects will have free flow if
they can pass a channel
without reducing speed
• Sufficient distance between
ships
• Traffic density
• Ship sizes and speeds
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FREE FLOW: SUFFICIENT DISTANCE
THE SAFETY ELLIPSE
Original safety ellipse theory by
Fujii (1971)
Navigators will try to avoid
having other ships within their
ships safety ellipse and will
avoid entering into another
ships safety ellipse
Verification in Great Belt,
Drogden, and Femern Belt
Checked for size, speed and type
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FREE FLOW: EFFICIENCY OF A WATERWAY –
CONCEPT OF FREE FLOW
"Ships sailing according to the ellipse theory will have free
flow if they can pass the channel without reducing speed.“
Free flow percentage =
Number of ships - (speed reductions + ellipse violations)
Number of ships
F
N  (S  E )
N
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FREE FLOW OBSERVATIONS
GREAT BELT AND DROGDEN
N  (S  E )
F
N
Observations of speed reductions and
ellipse violations is based on AIS data
Great Belt
Drogden
Speed reductions (S)
1% - 3%
2% - 6%
Ellipse violations (E)
3% - 4%
5% - 9%
Empirical free flow (F)
93% - 96%
85% - 93%
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Passenger
THEORETIC FREE FLOW
ALGORITHM
Tanker
1. Sample ships
2. Find ship locations in TSS
Other
Container
General
cargo
3. Find ellipse violations (E)
4. Free flow
F
N  (S  E )
N
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THEORETIC FREE FLOW
ALGORITHM
1. Sample ships
2. Find ship locations in TSS
3. Find ellipse violations (E)
4. Free flow
F
N  (S  E )
N
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THEORETIC FREE FLOW
ALGORITHM
1. Sample ships
2. Find ship locations in TSS
3. Find ellipse violations (E)
4. Free flow
F
N  (S  E )
N
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FREE FLOW VALIDATION
GREAT BELT AND DROGDEN
N  (S  E )
F
N
Theoretic free flow is in agreement
with observed free flow
Great Belt
Drogden
Speed reductions (S)
1% - 3%
2% - 6%
Ellipse violations (E)
3% - 4%
5% - 9%
Empirical free flow (F)
93% - 96%
85% - 93%
Theoretic free flow (F)
97%
90%
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Free Flow
Femernbelt
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FREE FLOW COMPARISON
N  (S  E )
F
N
Great Belt
Drogden
Speed
(S)
• Preductions
15 memo 95
Ellipse violations (E)
1% - 3%
2% - 6%
3% - 4%
5% - 9%
Empirical free flow (F)
93% - 96%
85% - 93%
Theoretic free flow (F)
97%
90%
Unhindered passage of
ferry line (F?)
Femern
849 m
Femern
Ferries
3%
90%
97%
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IN CONCLUSION
We propose:
Free Flow as a measure of water way efficiency
Lack of Free Flow =
Speed reductions +
Close navigation
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IN CONCLUSION
Use of Free Flow in the Fehmern project:
Tool for designing the channel size
(length and width)
Other uses:
Determining the need for
guided assistance (VTS)
Optimizing operating procedures
for VTS
Free flow
Input to choice of bridge span
Channel size
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FURTHER DETAILS
• VTS a risk reducer
Acknowledgements:
(Submitted for Journal of Navigation)
• Quantitative assessment of
risk to ship traffic in the
Femern Link project
Niels Jacob Mygind
Admiral Danish Fleet
Jørgen Brandt
Great Belt VTS
(Journal of Polish Safety and Reliability
Association 2012 )
• Ellipse theory journal paper
(In preparation)
• Free flow journal paper
(in preparation)
• www.femern.com
Contact
Tue Lehn-Schiøler
Senior consultant, Ph.D.
tuel@ramboll.dk
+45 5161 8387
www.ramboll.dk
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