Better Bike Lanes: Year One of Quantitative Evalutation
September 30, 2025
In July of this year, the City of Boston published the Better Bike Lanes Year One Quantitative Evaluation report, which assesses the safety and traffic impacts of seven recent bike infrastructure projects on City streets. The City of Boston launched the Better Bike Lanes initiative in 2022 with a goal of adding 9.4 miles to Boston’s bike network along with speed calming treatments in some areas. In 2023, seven key corridors received upgrades, including separated lanes, contraflow access, and speed humps to calm motor vehicle speeds. This evaluation describes the positive impacts for cycling and road safety, with negligible effects on car traffic.
A word about methodology:
This report compares baseline data collected in September 2022 with post-install data collected in September, 2024. In addition, the report contains control location data from 15 Boston streets of various size and type that have similar characteristics to the project streets but did not receive any bike infrastructure improvements during the study period. Note that control streets compare volume data only, as speed data was not available. Key takeaways from the report are summarized below:
Bicycling Volumes Increased Dramatically
- Biking rose by 44% on average across project corridors after improvements, while control streets (those without changes) saw a slight 3% decrease
- Streets with new contraflow bike lanes saw the highest gains, averaging 482%
- Six of the seven upgraded corridors saw an increase in daily cyclists, with some locations experiencing as much as a 194% jump. In the one corridor that saw a dip, the decline was just ten percent.
Road Safety Improved
- Speeding significantly decreased: six out of seven projects saw major drops in the fastest (95th percentile) vehicle speeds
- Compliance with Boston’s 25 mph limit rose by about 15% on improved streets
- Streets with added speed humps had the largest reductions in speeds
Motor Vehicle Traffic Was Largely Unchanged
- Motor vehicle volumes remained essentially flat (average change +1%), suggesting new bike lanes did not divert significant car traffic to other streets
Comparative Analysis: Project vs. Control Streets
- Project streets: +44% bikes, +1% cars
- Control streets: -3% bikes, +0.3% cars
- This clear contrast demonstrates the ability of upgraded infrastructure to increase people bicycling without an reducing the volume of motor vehicles
Conclusions
Boston’s targeted investment in bike infrastructure—separated and contraflow lanes plus speed humps—has led to substantially more bicycling, safer speeds for all users, and stable patterns for drivers. The data collected for this report provide strong support for continued expansion. In Fall 2025, the City plans to evaluate additional bike infrastructure installed in 2023-4. You can review and download the full report at this link. More information is included on the Better Bike Lanes webpage at https://www.boston.gov/government/cabinets/streets-cabinet/better-bike-lanes
