Knowledge CentreTechnical Resources SearchConference PapersGLOBAL APPROACHES TO SETTING SPEED LIMITS



Static maximum speed limits are set to inform motorists of appropriate driving speeds under favourable conditions, and are almost always enacted with an overarching goal of increasing safety while retaining reasonable mobility. The first speed limits actually predate the automobile, and as such they have a long and varied history in protecting the traveling public. Today, the speed limit is by far the most popular tool used by engineers and traffic engineering professionals to manage travel speeds. Besides being a popular Canadian road safety tool, speed limits are almost universally employed by all motorized countries. Despite the long and wide-spread use of speed limits as a road safety tool, there are numerous speed limit setting methodologies, and there is no consensus in the traffic engineering community on a single speed limit setting methodology. While there are literally countless guidelines/methods for setting speed limits, these methods can be roughly categorized into four general approaches. The purpose of this paper is to outline the four general approaches to setting speed limits that are available to the transportation engineering community, and to discuss the strengths and weaknesses of each. The four approaches to setting speed limits are the engineering approach (including the traditional use of the 85th percentile speed, and the road risk methodology), the expert system approach (including VLIMITS, USLIMITS), optimization (using speed limits to minimize the total societal costs), and the safe system approach (linking road types and crash types to travel speeds). 

Conference Paper Details

Session title:
Gerry Forbes
Road safety