The role of volume-delay functions in forecast and evaluation of congestion charging schemes...
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The role of volume-delay functions in forecast and evaluation of congestion charging schemes Application to Stockholm Leonid Engelson and Dirk van Amelsfort
The role of volume-delay functions in forecast and evaluation
of congestion charging schemes Application to Stockholm Leonid
Engelson and Dirk van Amelsfort The Royal Institute of Technology
and WSP Analysis and Strategy
Slide 2
Outline Background of the project Model validation by effects
of congestion charging Adjustment of VDF Results of the experiment
Conclusions and recommendations
Slide 3
Background Two research projects at CTS: Improvement of CC
system for Stockholm Transferability of Stockholm experience to
other cities Need a model to calculate benefits of CC Two state of
the art regional models were used for forecasts Destination and
mode choice Static assignment Comprehensive monitoring of CC
effects The observed effects differed from the model forecast Is it
possible to improve the model by small effort in order to be useful
for CBA?
Slide 4
The model SAMPERS a model for whole Sweden (5 regions,
national, international), Stockholm + MD = one of the regions
Nested logit demand model 6 travel purposes Frequency, destination,
mode choice Scaling demand matrices from day to assignment period
with fixed shares: AM peak, mid-day, PM peak Scaling to 5 VoT
classes with fixed shares Transit and auto assignments in Emme Auto
assignment with generalized cost with 5 VoT classes Feedback travel
time and cost to the demand model VDF for Stockholm estimated 1979,
adjustments in 80-s and 90-s Travel survey 1990-1995
Slide 5
The congestion charging system
Slide 6
Traffic flow over the cordon
Slide 7
Comparison of modeled and observed effects, aggregate By Jonas
Eliasson and Karin Brundell-Freij
Slide 8
The cordon and the AVI links
Slide 9
Measured 7:30-9:00T/RIMSamPers Traffic flow through the cordon,
no charges, veh/h358684229637182 Traffic flow through the cordon,
with charges, veh/h312382615326254 Relative change in
flow-13%-38%-29% Average speed on AVI links, with charges,
veh/h30.835.337.4 Average speed on AVI links, no charges,
veh/h34.937.939.4 Relative change in speed13%7.4%5.3% Speed change
to flow change ratio-0,2 Comparison of modelled and observed
effects, morning peak
Slide 10
Demand model or supply model? Flows change stronger than in
reality. Travel times change less than in reality If flow changes
are improved by better modelling the demand then the discrepancy in
time changes will be even worse The supply model needs improvement
in the first hand
Slide 11
To improve the static model No interaction at intersections No
back propagation of queues No queue building and dissipation
(average conditions) Still we can make VDF steeper in the static
model (our VDF are from 1978) Is it possible to calibrate a static
model with a VDF slope parameter ? Numerical experiment
Slide 12
Modification of VDF time v0v0 v 0 = flow in the base scenario t
0 = time in the base scenario volume t0t0 f g
Slide 13
Effect of k on modelled traffic flow and average speed k
Relative change of flow over the cordon Relative change of average
speed on AVI links Speed change to flow change ratio 1-29%5,3%-0.18
2-28%8%-0.29 3-27%9%-0.33 4-27%10%-0.37 10-26%15%-0.57
Observed-13%13% Still long to the observed ratio
Slide 14
Effects of k on benefit of the CC (SEK per day) k Surplus
change RevenuesBenefit 1-3 023 7373 532 497508 760 2-2 842 2903 591
849749 558 3-2 742 4753 629 175886 700 4-2 663 1673 663 9921 000
824 10-2 325 4443 772 6731 447 228 The benefit depends on k
Slide 15
Comparison of charging systems with different k 1.The current
system 2.The current system plus charge on Essinge bypass 3.The
current system plus charge for crossing the strait 4.The current
system plus charge for crossing the strait but not the Essinge
bypass 5.The current system plus charge for crossing the strait
plus charge on the Central bridge.
Slide 16
Gate locations in the four alternative charging systems
Slide 17
Ranking of different charging systems with k=1 and with k=10
(SEK per day) Charging system k=1k=10 Surplus change
RevenueBenefitRanking Surplus change RevenueBenefitRanking 1-3 0243
532508 7603-2 3253 7731 447 2283 2-3 8974 505608 2752-2 9774 7781
801 1792 3-5 0205 894873 5451-3 7916 2772 485 6941 4-4 4824 088-393
0805-4 0464 743697 0164 5-3 6613 75997 6504-3 5534 137584 2765
*1000
Slide 18
Conclusions Steeper VDF make the model better reproduce effects
of CC Even med much steeper VDF the model still underestimates the
speed change to flow change ratio With steeper VDF, the calculated
benefit of CC is substantially higher than with the original
VDF
Slide 19
Recommendations Static assignment models are not appropriate
for CBA of CC in cities, more advanced tools are needed When the
benefit of CC is calculated with a static model the sensitivity
analysis w r t slope of VDF is recommended (EMME macro is
available)