Comparing the existing Columbia River Interstate Bridge facility with the proposed design during PM peak usage conditions on the Northbound Side

1. Columbia River
Crossing Bottleneck
Simulation
BRYAN BLANC
ALI RAZMPA
1

2. Purpose
Use a simulation tool to analyze real-world data
Compare alternative designs for transportation facilities
and their effects on transportation operations
Columbia River Crossing Bottleneck Simulation 2

3. Objectives
Compare the existing Columbia River Interstate
Bridge facility with the proposed design during PM
peak usage conditions on the Northbound Side.
Propose minor improvements that can be made
to the bridge now, until full construction
(eventually) takes place on a new bridge
Columbia River Crossing Bottleneck Simulation 3

4. Study Boundaries
Analyzing average Friday conditions during Summer
(June-August) of 2013 between 12 PM and 10 PM.
Oregon
Washington
Segment Examined (Northbound only)
Image from Google Earth
Columbia River Crossing Bottleneck Simulation 4

5. Data Sources
Loop detector data for I-5 freeway segment and
on ramp volumes taken from PORTAL
Off ramp flows taken from Columbia River
Crossing Traffic Technical Report1
Heavy vehicle assumptions from Columbia River
Crossing technical report on existing freight
conditions2
1: http://www.columbiarivercrossing.org/FileLibrary/TechnicalReports/Traffic_TechnicalReport.pdf
2:http://www.columbiarivercrossing.org/FileLibrary/TechnicalReports/TruckFreightExistingConditions.pdf
Columbia River Crossing Bottleneck Simulation 5

6. Columbia River Crossing Bottleneck Simulation 6

7. Simulation Tool
VISSIM 6.0
Data Input :
Volume (vph)
Relative Flow (%)
Speed limits:
Interstate 5 = 55 mph
N Denver Ave to I-5 (on-ramp) = 45mph
Marine Dr. W to I-5 (on-ramp)= 25mph
N Hayden Island Dr to I-5 (on-ramp)= 25mph
Columbia river I-5 Bridge =50 mph
Driving behavior:
Vehicle Compositions:
Cars= 90%
Trucks= 8%
Buses= 2%
Signal Controllers:
Two Ramp Metering on on-ramps
Lane change: 5000 ft before the diverge & 3000 ft before the lane drop
Columbia River Crossing Bottleneck Simulation 7

8. Design Alternatives
Existing
6-lane freeway bridge, problematic accesses are primary cause of bottleneck
8
Image from Google Earth
Time Avg Speed Avg Delay
2:00 PM - 3:00 PM 18 mph 188 Sec

9. Proposed
12-lane freeway bridge, improved accesses
9
Time Avg Speed Avg Delay
2:00 PM - 3:00 PM 41 mph 8.5 Sec

10. Our Test Alternative
Remove on-ramp for Hayden Island on Northbound side.
Add one lane leading up to Columbia River Interstate Bridge (using existing shoulder)
10
Time Avg Speed Avg Delay
2:00 PM - 3:00 PM 26 mph 102 Sec

11. Average Speed
11
50
45
40
35
30
25
20
15
11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM
Average Speed (mph)
Existing Proposed Alternative
Columbia River Crossing Bottleneck Simulation

12. Total Travel Time on Segment
12
400
350
300
250
200
150
100
50
0
11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM
Total Travel Time on Segment (Vehicle-Hours Traveled)
Existing Proposed Alternative
Columbia River Crossing Bottleneck Simulation

13. Total Delay on Segment
13
250
200
150
100
50
0
11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM
Total Delay (Vehicle-Hours)
Existing Proposed Alternative
Columbia River Crossing Bottleneck Simulation

14. Difference in Performance
14
+60%
-30%
-80%
+44%
-16%
-50%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
Average Speed in Segment (mph) Total Travel Time in Segment (VHT) Total Delay in Segment (hours)
Proposed Alternative
Columbia River Crossing Bottleneck Simulation

15. Discussion
Estimated Costs:
Proposed: $3.1-3.5 Billion
Our Test Alternative:<$100 Million
Could removing accesses be a temporary solution to
mitigating congestion?
Is it politically feasible? (Beyond the scope of this
project)
Other Possibilities:
Demand reduction
Limits on freight travel during peak hours
Columbia River Crossing Bottleneck Simulation 15

16. Issues and Limitations
Data validity
Issues with speeds reported in PORTAL as compared to
those generated by simulation (using volumes from
PORTAL). Which is more reliable measure of speed?
Simplified test scenario
Simplifying assumptions were made that may not be
valid under realistic conditions
Study boundaries
Small portion of corridor was analyzed
Columbia River Crossing Bottleneck Simulation 16

17. 60
55
50
45
40
35
30
25
20
15
Average Speed
11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM
Average Speed (mph)
Simulated Portal
Columbia River Crossing Bottleneck Simulation 17

18. Columbia River Crossing Bottleneck Simulation 18

19. Project Outcomes
Gained experience in utilizing real world data with a
simulation tool
Simulation allowed us to gain greater understanding of
bottleneck conditions on Columbia River bridge
Columbia River Crossing Bottleneck Simulation 19

20. Questions?
Thank you for your attention!
20
Source:http://www.macalester.edu/academics/environmentalstudies/students/projects/citizenscience2010/columbiariverbridge/crcfuture.html