There are four main components of a Safe Speed Study: collect data, analyze existing conditions, determine how to manage speeds down, and evaluate changes.
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Begin by collecting data about corridor conditions and crash history.
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Analyze the corridor, focusing on the frequency of conflict and the amount of activity, and use the risk matrix to determine the appropriate posted speed.
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Decide on the best option to manage speeds along the corridor using the decision tree.
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Evaluate speed management efforts through pre- and post-implementation data evaluation.
A Safe Speed Study should be conducted for the longest relevant segment of a street corridor. If a corridor changes significantly at a specific point, it can be divided into two or more segments.
Cities should avoid studying every block or every segment of a long corridor. Instead, cities should identify key locations for study and select the lowest practicable speed limit for the longer segment to manage both safety and legibility along the corridor.
A Safe Speed Study can also be performed for a large area or district. As with corridor studies, it is not necessary to record data on every block within the district. Instead, district-wide corridor speed limits can be set based on an assessment of a typical street within that district. In most cases, selecting 20 to 30 representative blocks at random will provide a reasonable sample of speeds for a category of similar streets, regardless of the size of the city.