Synthesis of Safety for Traffic Operations - Transports Canada

Synthesis of Safety for Traffic Operations March 2003
• 08:00 to 09:30 hrs;
• 11:30 to 13:30 hrs; and
• 15:00 to 16:30 hrs.
In addition, signs were posted at the beginning of the zones. The study methodology was
a naïve before-after study using average speed. The treatment was evaluated during the
presence and absence of police enforcement. The results are shown in Table 8.10.
TABLE 8.10: Effects of 30 km/h School Zone Speed Limit on Average Speed in
Edmonton
Average Speed (km/h)
Site
After (No After
Before
police) (Police)
A 44.5 42.7 N/A
B 49.7 47.2 44.9
There is a marginal reduction in speed at both locations, the police presence increase the
effect. It is not reported whether this change is statistically significant. The researchers
also evaluated the effects of the treatment on speed limit compliance. While voluntary
compliance is an important policy consideration, there is no credible evidence to suggest
that compliance is correlated with crash occurrence or severity. Hence, this information
is not repeated here.
Research on the safety impacts of speed limits is fractured. The less than ideal conditions
in which speed-safety studies must take place are difficult if not impossible to overcome,
and this has lead to conflicting results. Nonetheless, it seems that there are three
monographs that present comprehensive reviews and are likely to provide the practitioner
with the most complete picture respecting speed limits and safety. They are:
• IBI Group (1997) “Safety, Speed & Speed Management: A Canadian Review”,
Final Report, Transport Canada, Ottawa, Ontario.
• Parker MR (1997) “Effects of Raising and Lowering Speed Limits on Selected
Roadway Sections”, FHWA-RD-92-084, United States Department of
Transportation, Federal Highway Administration, Washington, DC.
• Managing Speed: Review of Current Practice for Setting and Enforcing Speed
Limits. Transportation Research Board, Special Report 254. Washington, DC,
1998.
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