Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
HOW THE FUTURE TRANSPORTATION SYSTEM COULD WORK
Imagine four different travelers:
• Anne: a business person working in the northern suburbs of a major city, needing to travel
to an afternoon meeting in the southwest portion of the city.
• Fred: also lives north of the city. He works the late shift as a janitor. He needs to be at
work by 5:00 PM and comes home at 1:00 AM. He drives to work despite his limited
income because the bus service is infrequent when he comes home at 1:00 AM.
• Armand: also lives north of town. He is on his normal day off from work and is planning to
make a shopping trip to the large mall west of town to visit a new department store.
• Giovanni: a shipping services manager for a distribution company whose warehouse is
located north of the city. He needs to deliver a shipment of high priority, just-in-time goods
to a customer by 3:30 PM or face a late fee of $300 for every ten minutes the delivery is
late.
With “normal” traffic, all four travelers had planned to use the general purpose lanes on the
Western Loop Expressway to reach their destinations. However, today a major crash occurred at
2:45 PM on the Western Loop. An older model car (one without the new, automated tire pressure
warning gauges) blew a tire and swerved into the car next to it. Because the traffic volumes are at
85 percent of capacity in the middle of the day on the general purpose lanes of the Western Loop,
the high density of vehicles caused several other cars to be involved in the crash. The automated
braking systems of those cars limited the size and scope of damage to them, but two of three lanes
are closed, and emergency medical services are needed for the occupants of the older model
vehicle.
Because of the size of the crash and the high volume/capacity ratio on the roadway, heavy
congestion quickly forms on the Western Loop. Travel times for all vehicles using the Western
Loop increase. However, as a result of the private and public sector roadway performance data
collection systems (as well as the mayday system in the newer model car that was hit) the traffic
management center (TMC) knows immediately that a crash has occurred.
Agency Responses to the Crash on the Western Loop
The TMC dispatches traffic management personnel, crash investigation personnel, and emergency
services personnel (on the basis of a combination of the mayday information and video
surveillance of the scene). TMC staff also enters the basic parameters of the crash - describing the
event into their traffic management software (two lanes blocked, five cars involved, EMS
involved). The freeway management software automatically adjusts the active traffic management
system for the Western Loop, which includes the following:
• broadcasting the lane closure information on the crash notification website while also
“pushing” that information to all public and private participants in the crash notification
program
• forecasting the expected delays on the basis of an expert system that integrates information
on current traffic volumes, expected future demand, and the size/scope of the crash
A CONCEPT OF OPERATIONS Page 121