1. RELIEVING CONGESTION
Keeping the Nation’s Arteries and Travel Ways Unclogged
~Anyesha Mookherjee
Traffic Engineer, URS Corp

2. The Text Book Definition
“Traffic Engineering is that phase of transportation engineering which deals with the planning, geometric design and traffic operations of roads, streets, and highways, their networks, terminals, abutting lands, and relationships with other modes of transportation.”
Traffic Engineering by Roess, Prassas and McShane

3. What it Actually Means
Provide transportation from point A to point B that is:
Safe
Fast
Comfortable
Convenient
Economical
Environmentally Compatible

4. Congestion
Congestion results when traffic demand approaches or exceeds the available capacity of the system
Congestion on roadways leads to
Increased frequency of crashes
Increased average trip times
Increased fuel consumption
Increased green house gas emissions

5. Leading Causes
According to FHWA (Federal Highway Administration), the leading causes of congestion on US roadways are
Bottlenecks
Traffic Incidents
Work Zones
Bad Weather
Poor Signal Timing
Special Events

6. The Congestion Relief Toolbox
Improve Service on Existing Roadways
Add Capacity
Electronic Toll Collection and Pricing
Better Work Zones
Travel Options
Traveler Information

7. Improving Service on Existing Roadways
Access Management
Traffic Incident Management
Traffic Signal Timing

8. Access Management
At urban intersections separate out the critical turning volumes and provide exclusive turn lanes
Major street with shared left through movements causes through vehicles to queue behind left turning vehicles
Major street with dedicated left turn lanes movements removes left turning vehicles from the paths of through vehicles

9. Access Management
Channelize heavy/critical turning movements

10. Traffic Incident Management
Improve response time for first responders to roadway crashes
Provide breakdown lanes
Centralized traffic management centers
Provide real time data about crash via Highway Advisory Radio (HAR)/AM and FM radio/TV/Highway signs

11. Traffic Incident Management - A Real Time Example

12. Traffic Incident Management-A Real Time Example
Timeline of Events
January 13, Tuesday 2:45 p.m. Tanker truck explodes on I–95, closing interstate in both directions 2:46 p.m. Patroller alerts Maryland State Highway Administration (MSHA) of incident 2:47 p.m. Patroller begins turning vehicles around at the scene. 2:54 p.m. Electronic message signs changed on I–95 to inform motorists that the interstate near Baltimore is closed. Traffic redirected to alternate routes 3:06 p.m. First fire department arrives on the scene 3:45 p.m. The majority of the fire is under control 7:00 p.m. Two of the four lanes of southbound I–95 reopen.
11:30 p.m. All lanes of I–895 reopen
January 14, Wednesday 1:30 a.m. Fire crews wash down roadway 2:15 a.m. Southbound lanes of I–95 reopen 3:35 a.m. Northbound lanes of I–95 reopen
Two firefighters work to control the flames on a tractor trailer that was caught in the explosion of the fuel tanker

13. Traffic Signal Timing Pre-timed signals vs. actuated signals
Loop detectors
Camera detectors
Optimization of cycle length
Synchro/SIMTraffic
Systemization of signals within corridor
Interconnect signals
Optimize network using Synchro/SIMTraffic
Adaptive traffic control systems
Split Cycle Offset Optimization Technique (SCOOT)

14. Add Capacity Construction of additional traffic carrying lanes
Additional freight rail and light rail service
Incorporate pedestrian paths and trails

15. Capacity Improvement – Woodrow Wilson Bridge Project
The original bridge was opened to traffic in 1961.
Was designed to carry 75,000 vehicles per day in the year 2020
Currently carries 195,000 vehicles per day and is projected to carry 295,000 vehicles per day by 2020
Existing six lane configuration inadequate, causes seven hours of congestion and several mile long backups daily
The drawbridge opened 260 times a year

16. Woodrow Wilson Bridge Project
New span will have
Ten lanes of traffic to carry I-495 traffic
Two lanes for future rail use in the median
20 feet higher, will only open 65 times a year after completion

17. Electronic Toll Collection (ETC) and Pricing
ETC is a technological implementation of a pricing concept using RFID transponders mounted in vehicles
It determines whether the cars passing are enrolled in the program
It alerts enforcers for those that are not
It debits electronically the accounts of registered cars without their stopping, or even opening a window

18. Electronic Toll Collection (ETC) and Pricing
High Occupancy Toll (HOT) lanes: On HOT lanes, low-occupancy vehicles are charged a toll, while High-Occupancy Vehicles (HOVs) are allowed to use the lanes for free or at a discounted toll rate
Variable Pricing: Pricing on toll facilities are varied by time of day with the intention of encouraging some travelers to:
use the roadway during less congested periods
shift to another mode of transportation
change routes

19. Better Work Zones Plan ahead
Use available traffic models to predict effect of closing traffic lanes on queues
Restrict lane closures to off peak and weekend hours
Involve the community. Get the word out

20. Travel Options Travel Demand Management
Special Events Traffic Management

21. Travel Demand Management
Evaluate the effect of new development on existing roadway system
Place the onus of mitigating congestion caused by new traffic on developer
Project traffic demand based on land use and plan accordingly
Provide traveler with options:
Tax incentive for transit
Park and ride
Share-a-ride
Transportation Demand
Transportation Facilities
Land Use

22. Special Events Management
Parades, games, seasonal tourism can place a sudden burden on the roadway system
Easy to plan ahead as event is not of an unexpected nature
Community and police involvement essential
Detour traffic through alternate routes
Establish a system of one-way routes
Establish more parking

23. Traveler Information
Creation of 511 for traffic, similar to 911 for emergency
Dynamic Message Signs
Real Time Travel Time Information
Web based
Radio based
TV based

24. Real Time Travel Time Information
Screenshot of traffic conditions in area highways on September 18th 2007 at 5:00 PM from

25. No one strategy can solve the congestion problem
In a Nutshell…
No one strategy can solve the congestion problem

26. Questions Anyone? Useful websites: Feel free to contact me at
Feel free to contact me at