Islandwide Speed Limit Study

Background

The citizens of Bainbridge Island periodically request that the Public Works Department perform traffic studies on individual road sections around the Island to evaluate the existing speed limits and see if they need to be adjusted. The objective of this project is to look at all of the Island’s speed limits at once, including those that are currently posted and unposted with speed limit signage. The project team will recommend and adopt speed limit changes to the entire road network to avoid the need to perform speed limit reviews on a case-by-case basis. Such an effort will help to ensure consistency in posted speed limits across the Island. The evaluation will utilize a recent comprehensive inventory of speed limits and a speed/volume data collected by the City. Transpo Group USA, Inc., a traffic engineering consultant, will provide transportation planning services to the City to complete the programmatic evaluation of posted speed limits for all public roadways within the City. 

Scope of Work

Transpo and the Public Works Department will review potential strategies for assessing all of the Island speed limits at once, to include looking at arterial and collector roads individually, while primarily studying local access roads as a group, as their speed limits are set by City Code. The project will also look to see if the City Code requirements for local access roads should be changed. Transpo will obtain and review the comprehensive inventory of vehicle speeds and traffic volumes, existing speed limits, and recorded speed limit modification requests from the City. The information will be used to develop maps and spreadsheets of the roadway system to compare current speed limits, traffic volumes, 50th and 85th percentile speeds, and public requests for speed limit changes. The information would be evaluated to identify correlation and/or inconsistencies between the data which could be used as a starting point for the evaluation. The project team will summarize research and outcomes from other similar studies nationwide to identify and confirm best practices agencies employ when setting or modifying posted speed limits. National and local publications from federal, state, and local agencies, professional organizations, and industry groups will be summarized to identify key information that would be useful to consider as part of the evaluation. 

The project team will then develop criteria to be used to make programmatic modifications to the posted speed limits. The information and results will be reviewed with City staff to obtain feedback and guidance on the criteria, before presenting the information to City Council. Adjustments to the criteria will be considered based on Council and Staff input. The final result will be a set of speed limit signing changes across the Island to better represent the City’s ideals of traffic safety and maintaining the rural characteristic of the Island.

Status

Ordinance 2023-03, adopted by the City Council on January 24, 2023, enacts changes to many of the island’s speed limits. Speed limits will decrease by no more than 5 MPH on numerous major and minor roads (see maps below). The majority of local access roads will have a default speed limit of 20 MPH unless otherwise posted.

Beginning March 1st, the City will be implementing the first phase of speed limit sign changes. The installations are expected to take 7-8 weeks and will address speed limit changes on arterial and collector roads only. 

BIPD has been informing the community of the upcoming speed limit changes through web-communications, direct mailers, and handouts distributed by officers. The new speed limit signs will be flagged, and mobile speed trailers will be deployed to add emphasis to the changes. 

Following installation of new signs, additional speed emphasis patrols will be conducted based on the new limits. During the 30-day period following installation, warnings will be the primary means of enforcement for most violations. Officers will continue to distribute information on the speed limit changes during traffic stops.

In late April, the Department will begin speed limit sign installation and changes for the local neighborhood access roads.