Experience managing smart work zones in the St. Louis area.
This study evaluated the use of traveler information to promote traffic diversion during bridge reconstruction on I-70 in St. Louis. To accommodate closure of five westbound lanes at the Blanchette Bridge, five eastbound lanes were reduced to three lanes in each direction for period of one year beginning in November 2012. During construction, permanent dynamic message signs (DMS) on I-70 were programmed to notify drivers of lane closures, narrowed lanes, and reduced speed limits, provide travel times, and divert traffic to Rt. 364 and Rt. 370 during periods of congestion. To assess performance, an evaluation framework and simulation model were developed to estimate impacts on delay and queue lengths with and without ITS. Traffic data collected from traffic sensors and video cameras at ramps were used to capture the effects of messaging on diversion rates. In addition, a traveler survey was conducted to evaluate traveler behavior and driver compliance. The survey included 496 respondents.
- The I-70 ITS deployment resulted in a cost of $198,530, a benefit of $407,694 and a benefit-to-cost ratio of 2.1:1.
- If the cost of existing ITS equipment (DMS system) were not included in the calculation, and only the $59,130 cost for increased ITS operations was accounted for, the benefit-to-cost ratio would increase to 6.9:1.
- Fifty-two (52) percent of drivers said they used an alternative route due to DMS.
- Almost all drivers (98 percent) were aware of the I-70 work zone before starting their trip. Thus the DOT was successful in disseminating traveler information through various media outlets advising the travelers about the work zone.
- Awareness of the work zone led to increased use of alternative routes. Comparing morning and evening commutes, alternative route usage was greater in the evening.
- With respect to delays reported by drivers, delays were longer (over 15 minutes) if drivers were not aware of the work zone.
- With respect to delays reported by drivers, delays were longer (over 15 minutes) if drivers were not influenced by DMS.
- DMS had the greatest influence on drivers 46 to 65 years of age.