Traffic Speed Studies

data.cambridgema.gov | Last Updated 16 Apr 2019

The Traffic, Parking &Transportation department has conducted over 600 speed studies since 1987. Some locations have been studied more than once. The speed of each passing vehicle is recorded by radar for an hour each in the morning rush hour, evening rush hour, and midday. From these results, we find the 85th percentile speed for each one-hour period. The 85th percentile speed describes a speed that 85% of drivers are traveling slower than (and 15% of people are driving faster than). Traffic engineers use 85th percentile speed for most traffic safety analyses and design standards. In this dataset, the speed reported is the highest 85th percentile speed for all three one-hour periods studied.

Tags: speed, traffic, congestion, vision zero, car, vehicle, crash, accident

This dataset has the following 9 columns:

Column NameAPI Column NameData TypeDescriptionSample Values
Datedatecalendar_dateDate of study.
StreetstreettextName of street being studied.
Cross Streetcross_streettextName of nearest crossing street at observation area OR street number.
LatitudelatitudenumberApproximate latitude of the study.
LongitudelongitudenumberApproximate longitude of the study.
DirectiondirectiontextDirection of flow of traffic.
Speed 85th Percentilespeed_85thnumberThe speed at which 85% of the traffic was clocked slower than.
Posted Limitposted_limittextPosted speed limit in miles per hour (MPH). U = Unposted.
Location for Mappinglocation_for_mappinglocationLocational column for mapping this dataset within Socrata.