Commonway
Version V. 2026.09.03

Protected bike lane retrofit via lane-width reallocation

RFT-CDR-07 Corridor

Protected bike lane retrofit via lane-width reallocation

Installs a physically separated bike lane by narrowing existing travel lanes and reallocating the recovered width, without removing a lane or on-street parking.

#Overview

This is the lightest-touch of the three protected bike lane retrofits. AASHTO's Green Book allows narrower vehicle lanes, down to 10 feet, in many contexts, and a four-lane arterial with turn lanes can often be restriped during routine maintenance to include a buffer and a physically separated bike lane without touching lane count or parking at all.1

#Where this leads: Target patterns

Bike Highway / Greenway (COL-BHG-04), Default (Standard Collector) (COL-DEF-01) with Protected Bike Lane / Cycle Track (ELM-PBL-37)

#Applicability and thresholds

Most applicable where existing lanes are wider than required for safe operation at the corridor's design speed, giving enough recoverable width to build a genuine physical buffer rather than a painted line alone.

#Evidence and effectiveness

FHWA identifies planned road diets and similar retrofits of higher-speed roads as prime opportunities to add separated bike lanes, since the same width analysis that supports a lane diet or road diet also identifies the space available for a buffer and protected lane.2

#Getting it built

Restriping-based, so it can move through the full construction spectrum starting from paint and flexible delineators at the demonstration or pilot stage, before committing to permanent curb or planter-based separation. See Construction Methodology & The Build Spectrum.

#Who can move this

Usually a city or county public works decision, achievable through routine restriping maintenance in many cases. See Legal & Planning Mechanisms.

Protected bike lane retrofit via lane removal (RFT-CDR-08), Protected bike lane retrofit via parking reduction (RFT-CDR-09) (the other two approaches to the same underlying goal, distinguished by where the recovered width comes from)

#References

  1. Legal / regulatory AASHTO, A Policy on Geometric Design of Highways and Streets (Green Book), lane width criteria.
  2. Evidence-based Federal Highway Administration, "Separated Bike Lanes," Bicycle and Pedestrian Program.

Suggest changes to this page (opens in new tab) Last updated September 3, 2026