There are four main components of a Safe Speed Study: collect data, analyze existing conditions, determine how to manage speeds down, and evaluate changes.
Begin by collecting data about corridor conditions and crash history.
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.
Decide on the best option to manage speeds along the corridor using the decision tree.
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.