Study Details

Study Title: Evaluation of the Scottsdale Loop 101 automated speed enforcement demonstration program

Authors: Shin et al.

Publication Date: MAY, 2009

Abstract: Speeding is recognized as a major contributing factor in traffic crashes. In order to reduce speed-related crashes, the city of Scottsdale, Arizona implemented the first fixed-camera photo speed enforcement program (SEP) on a limited access freeway in the US. The 9-month demonstration program spanning from January 2006 to October 2006 was implemented on a 6.5 mile urban freeway segment of Arizona State Route 101 running through Scottsdale. This paper presents the results of a comprehensive analysis of the impact of the SEP on speeding behavior, crashes, and the economic impact of crashes. The impact on speeding behavior was estimated using generalized least square estimation, in which the observed speeds and the speeding frequencies during the program period were compared to those during other periods. The impact of the SEP on crashes was estimated using 3 evaluation methods: a before-and after (BA) analysis using a comparison group, a BA analysis with traffic flow correction, and an empirical Bayes BA analysis with time-variant safety. The analysis results reveal that speeding detection frequencies (speeds greater than or equal to 76mph) increased by a factor of 10.5 after the SEP was (temporarily) terminated. Average speeds in the enforcement zone were reduced by about 9mph when the SEP was implemented, after accounting for the influence of traffic flow. All crash types were reduced except rear-end crashes, although the estimated magnitude of impact varies across estimation methods (and their corresponding assumptions). When considering Arizona-specific crash related injury costs, the SEP is estimated to yield about $17 million in annual safety benefits.

Study Citation: Shin, K., Washington, S., van Schalkwyk, I., "Evaluation of the Scottsdale Loop 101 automated speed enforcement demonstration program." Accident Analysis and Prevention, Vol. 41, No. 3, Oxford, N.Y., Pergamon Press, (2009) pp. 393-403.


CMFs Associated With This Study

Category: Advanced technology and ITS

Countermeasure: Implement automated speed enforcement cameras

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.37 63 4 Stars Single vehicle All Principal Arterial Other Urban
0.52 48 4 Stars Sideswipe All Principal Arterial Other Urban and suburban
0.74 26 3 Stars Rear end All Principal Arterial Other Urban
0.12 88 4 Stars Angle,Cross median,Day time,Dry weather,Fixed object,Head on,Left turn,Nighttime,Non-intersection,Parking related,Rear to rear,Right turn,Run off road,Speed related,Truck related,Vehicle/bicycle,Vehicle/pedestrian,Wet road All Principal Arterial Other Urban
0.46 54 4 Stars All All Principal Arterial Other Urban
0.57 43 3 Stars Single vehicle A,B,C Principal Arterial Other Urban
0.36 64 4 Stars Sideswipe A,B,C Principal Arterial Other Urban
0.77 23 3 Stars Rear end A,B,C Principal Arterial Other Urban
0.14 86 4 Stars Angle,Cross median,Day time,Dry weather,Fixed object,Head on,Left turn,Nighttime,Non-intersection,Parking related,Rear to rear,Right turn,Run off road,Speed related,Truck related,Vehicle/bicycle,Vehicle/pedestrian,Wet road A,B,C Principal Arterial Other Urban
0.52 48 4 Stars All A,B,C Principal Arterial Other Urban
0.33 67 4 Stars Single vehicle O Principal Arterial Other Urban
0.57 43 4 Stars Sideswipe O Principal Arterial Other Urban
0.69 31 3 Stars Rear end O Principal Arterial Other Urban
0.1 90 4 Stars Angle,Cross median,Day time,Dry weather,Fixed object,Head on,Left turn,Nighttime,Non-intersection,Parking related,Rear to rear,Right turn,Run off road,Speed related,Truck related,Vehicle/bicycle,Vehicle/pedestrian,Wet road O Principal Arterial Other Urban
0.44 56 4 Stars All O Principal Arterial Other Urban