Knowledge Resources

The Federal Highway Administration (FHWA) partnered with the American Association of State Highway and Transportation Officials (AASHTO) to encourage the implementation of work zone ITS through an AASHTO Technology Implementation Group project. This effort led to a workshop in September 2005, in St. Louis, MO at which Brian Sneed, ITS Engineer with the Illinois Department of Transportation (IDOT), gave a presentation on the I-64 add-lane construction project. Work zone ITS is used in the construction project to monitor traffic, reduce congestion, and promote safety.

The construction project covers 7.7 miles along I-64 about eight miles east of East St. Louis. The project includes the addition of a lane in each direction for a total of six lanes, structure, highway lighting, and signal improvements when completed. Scheduled for completion in July 2007, the construction project began in February 2005. Total construction contract award amount is $56 million.

Work zone ITS was selected for this project for a number of reasons:

• High vehicular volume, recurring PM traffic congestion, grade change, and limited access
• Increased traffic during the holiday season
• High-profile project
• Parallel alternate routes

The work zone ITS – also referred to as the Traffic Monitoring System (TMS) includes:

• Twelve (12) variable message signs (VMS) located within the work zones as well as in advance of the work zone so travelers can determine whether or not to take alternate routes.
• Total of 10 sensors (side-fire radar devices which detect traffic in each direction) along I-64 located within the work zone as well as on each end (exit/entrance) of the work zone area. These sensors are mounted on portable trailers and measure speed, volume, and occupancy lane-by-lane.

The data collected by the sensors is processed by a commercial off-the-shelf software package. Real-time information about traffic conditions is posted to the variable message signs and is automatically posted to the www.64addlane.com Web site (the temporary Web site was taken off line upon project completion). Data are transmitted via cellular-IP back to the server located at the vendor's site. IDOT traffic center staff have the capability to change the messages displayed on the VMS throughout the work zone area. Text and e-mail alerts are transmitted when pre-determined thresholds are reached.

The TMS will be deployed for 30 months at a cost of $14,500 per calendar month, which equates to $435,000. The total cost of the TMS is less than 1 percent of the total construction cost. The TMS was leased as part of the overall construction contract.