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Title:Speed Photo-Radar Enforcement Evaluation in Illinois Work Zones
Author(s):Benekohal, Rahim F.; Hajbabaie, Ali; Medina, Juan C.; Ming-heng Wang; Chitturi, Madhav V.
Subject(s):Work zone automated speed management, speed photo radar enforcement, SPE, work zone speeding and speed limit, police presence, speed display d trailer, construction zone speed reduction, police presence temporal (halo) and spatial effects
Abstract:The effects of an automated Speed Photo-radar Enforcement (SPE) system on the speed of vehicles in highway work zones were evaluated in this study. The SPE effects were also compared to other speed management treatments, including speed display trailers, police presence (with the patrol emergency lights on and off), and the combination of speed display trailer and police presence. Three datasets were collected in two work zones and the effects were studied at the location of the treatment and also at a location about 1.5 miles downstream in the work zone (spatial effects). The halo effects (temporal effects) of police presence and SPE, after they left the work zone, were also analyzed. Results are presented separately for cars and trucks in free-flow and in the general traffic stream in the median and shoulder lanes. SPE reduced the average speed of free flowing cars in the median lane by 6.3-7.9 mph and in the shoulder lane by 4.1-7.7 mph. The reductions brought down the average speeds near or below the posted speed limit of 55 mph. In addition, the SPE reduced the speeding by 40-51% in the median and by 7-57% in the shoulder lane for free flowing cars. Similarly, for free flowing trucks SPE reduced the average speed in the median lane by 3.4-6.9 mph and in the shoulder lane by 4.0-6.1 mph, to speeds below the posted speed limit of 55 mph. SPE also reduced the speeding free flow trucks by 10-53% in the median lane and by 0-56% in the shoulder lane. For the general traffic stream, SPE reduced average speeds by 5.1-8.0 mph in the median lane and by 4.3-7.7 mph in the shoulder lane. Likewise, trucks in the general traffic stream traveled 3.7- 5.7 mph slower in the median and 3.9-6.4 mph slower in the shoulder lane. SPE lowered the average speed of the general traffic stream below the speed limit in all cases. SPE was as effective as the police patrol presence with the emergency lights off. In two of the three datasets, SPE had 2.0-3.8 mph spatial effects on free flowing cars and 1.1-1.9 mph on cars in the general traffic stream. However, on all three datasets SPE had 0.8-5.3 mph spatial effects on free flowing trucks and 0.9-3.2 mph on trucks in the general traffic stream. The reduction in the percentage of downstream speeding drivers varied from 0%-44%. Finally, halo effects were very limited and only observed for SPE on free-flowing heavy vehicles in one work zone and free flowing cars in the second work zone. Police presence did not have halo effects.
Issue Date:2010-01
Series/Report:ICT-10-064 UILU-ENG-2010-2004
Genre:Technical Report
Type:Text
Language:English
URI:http://hdl.handle.net/2142/45957
ISSN:0197-9191
Publication Status:published or submitted for publication
Peer Reviewed:not peer reviewed
Sponsor:ICT-R56
Rights Information:No restrictions. This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161
Date Available in IDEALS:2013-11-05


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