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Alberta Intersection Safety Device Evaluation

Hours Posted on Hours Updated on

Author(s): Marlene Anderson, Tara Peters, Liz Owens

PowerPoint Presentation Only (no paper submitted):

3B - Owens

Abstract:

BACKGROUND

Red light cameras (RLC) have been used by various Alberta municipalities since January 1, 1999.  Amendments to the Traffic Safety Act came into force January 1, 2009 allowing the use of intersection safety cameras (ISC) at “red light camera” locations, high collision locations and where violations are frequent.   Alberta Transportation contracted with AECOM to evaluate the impact on safety of these devices.

AIMS -  The terms of reference  outlined the following questions:

How have RLC impacted:

  1. the number of collisions at monitored intersections?
  2. collision severity (fatal, injury, property damage) at monitored intersections?
  3. the type of collisions occurring at monitored intersections (e.g., angle, rear-end, etc.)?
  4. the number of red light violations occurring at monitored intersections?

How have ISC impacted:

  1. the number of collisions at monitored intersections?
  2. collision severity (fatal, injury, property damage) at monitored intersections?
  3. the type of collision occurring at monitored intersections?
  4. the number of speed violations occurring at monitored intersections?
  5. the speed at which monitored vehicles travel?

METHODS
• Results are based on an empirical Bayes analysis that estimates the number of collisions expected at intersections if a RLC or ISC was not present compared against the number of observed collisions when the RLC or ISC was in operation.

RESULTS
• RLC – findings
o 32.4 per cent decrease in casualty collisions
o 3,391 collisions expected, 2,291 observed
o 37.7 per cent decrease in angle collisions
o 1,813 collisions expected, 1,129 observed
o 7.7 per cent increase in rear-end collisions
o 4,785 collisions expected, 5,152 observed
o 1.4 per cent increase in property damage collisions
o 7,550 collisions expected, 7,654 observed
o 8.4 per cent decrease in total collisions
o 10,854 collisions expected, 9,945 observed
• ISC – findings
o 32.3 per cent decrease in casualty collisions
o 508 collisions expected, 344 observed
o 31.3 per cent decrease in angle collisions
o 214 collisions expected, 147 observed
o 9.4 per cent increase in rear-end collisions
o 1,272 collisions expected, 1,392 observed
o 10.6 per cent increase in property damage collisions
o 1,759 collisions expected, 1,946 observed
o 1 per cent increase in total collisions
o 2,267 collisions expected, 2,290 observed
DISCUSSION
The results show these devices are effective in reducing casualty and angle collisions by getting motorists to slow down and not run through red lights.

CONCLUSIONS
The study concluded that there is an overall positive net benefit from the use of intersection safety devices. Recommendations were also made for future consideration in terms of data collection.