Citation

Moore-Ritchie C, Kienitz H, Sohrweide T. Transport. Res. Synth. 2023; (TRS2301): 1-45.

Copyright

(Copyright © 2023, Minnesota Department of Transportation)

DOI

unavailable

PMID

unavailable

Abstract

Minnesota statute provides for a wide range of school zone speed limits (SZSLs) from which local authorities may select. This Transportation Research Synthesis summarizes the current research regarding setting SZSLs, effective methods and procedures for setting school zone speed limits and known spillover or other unintended consequences for setting improper school zone speed limits to provide guidance on SZSL best practices. The majority of states use a statute to define a SZSL, with over half of these states having a statutory SZSL set at 15, 20 or 25 mph. Many allow jurisdictions to lower SZSLs further based on an engineering and traffic study. Minnesota statute allows for a larger range than any other state. Based on available research, SZSLs consistently reduce mean and 85th percentile speeds, however the extent of the reductions and statistical significance varies. In many cases, a SZSL resulted in lower compliance with speed limits, however, lower overall speeds and tightening and leftward shift of speed distributions indicate overall safety benefits. Crash histories through school zones overwhelmingly found reductions in crashes, in particular, reductions in fatal and serious injury crashes involving vulnerable roadway users. The speed differential between the approach speed limit and the SZSL has an impact on compliance and safety, with a recommended differential of 5 to 10 mph and speed buffer zones on high-speed roadways. The layering of additional countermeasures such as flashing beacons and geometric changes to the roadway are recommended as best practices to achieve lower speeds in school zones. No unintended consequences on vehicle speeds nor user safety were identified.

Language: en