An automated workzone information system (AWIS) was deployed near Los Angeles, California on Interstate 5 between Magic Mountain Parkway and Rye Canyon Road. One southbound lane and one northbound lane adjacent the median were closed leaving three lanes in each direction open to motorists. The AWIS included vehicle detectors and three portable dynamic message signs (DMS). During traffic congestion, DMS messages suggested that drivers exit the freeway and use an alternate arterial route, the Old Road. Based upon detected traffic conditions in southbound lanes, the following messages were displayed on the DMS:
- TRAFFIC JAMMED alternating with SOUTH 5 AT RYE CANYON.
- SLOW TRAFFIC AHEAD alternating with PREPARE TO STOP.
- TRAFFIC JAMMED NEXT 2 MI alternating with EXPECT 5 MIN DELAY.
- TRAFFIC JAMMED AHEAD alternating with 126 FWY TO MAGIC MOUNTAIN.
- SOUTH 5 TRAFFIC JAMMED alternating with AUTOS USE NEXT EXIT.
- JAMMED TO MAGIC MOUNTAIN alternating with EXPECT 10 MIN DELAY.
- JAMMED TO MAGIC MOUNTAIN alternating with EXPECT 15 MIN DELAY.
- TRAFFIC JAMMED TO MAGIC MTN alternating with AVOID DELAY USE NEXT EXIT.
- TRAFFIC JAMMED ROUTE 126 TO MAGIC MTN.
- SOUTH 5 ALTERNATE ROUTE alternating with AUTOS USE NEXT 2 EXITS.
Researchers used traffic flow data and a driver survey to assess the effectiveness of the AWIS. For weekend and holiday periods when congestion was expected, traffic volumes and diversion rates were estimated using a proportion-based method. Traffic volume and speed data were collected with vehicle detectors and speed guns. The before data were collected on August 17, 2003 and after data were collected on September 1, 2003 during the Labor Day holiday. Using traffic volume and speed data, researchers found that diversion rates ranged from 5.3 to 20.2 percent. Most diversions occurred during congested periods with significant delay. Drivers who used alternate routes saved between two and four minutes. Researchers concluded that the AWIS was effective in diverting traffic and promoting smoother traffic flow during congested periods.
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