---
title: "Protected bike lane retrofit via lane-width reallocation"
url: "https://commonwaysystem.org/retrofits/corridor/protected-bike-lane-width-reallocation/"
id: "RFT-CDR-07"
description: "Installs a physically separated bike lane by narrowing existing travel lanes and reallocating the recovered width, without removing a lane or on-street parking."
updated: "2026-10-18"
---

RFT-CDR-07

# 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.

## Strategy viewer

Illustration in progress

No illustration of Protected bike lane retrofit via lane-width reallocation has been made yet. Interactive views are planned for every pattern and Retrofit Strategy.

## 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]

## Related Media

The items below come from outside the Commonway System, external videos, podcasts, and articles related to this page's topic, not part of the guidebook itself.

3 items

-   Aligned
    
    ### [Are Streets Too Complicated Now?](https://www.youtube.com/watch?v=u1Xs5EA5_uU)
    
    City Beautiful
    
    Asks whether today's proliferation of lines, signals, and lane types on streets is overcomplication or a needed response to modern demands, a question that runs directly through CS's Element-scale catalog and the density-tiered Corridor retrofit paths this video is tagged to.
    
    MED-004
    
-   Aligned
    
    ### [Dutch-style intersection design: bike-friendly](https://www.youtube.com/watch?v=yCzi1Q4xCTA)
    
    BicycleDutch
    
    Shows the protected-intersection design vocabulary, continuous cycle tracks, corner refuge islands, separated signal phasing, that underpins CS's Protected Intersection pattern and the Corridor retrofit paths built around it.
    
    MED-005
    
-   Aligned
    
    ### [America's deadliest road, explained](https://www.youtube.com/watch?v=0-nthHT-J1k)
    
    Vox
    
    Vox examines a one-kilometer stretch of US-19 in Florida, the deadliest of 60 pedestrian-fatality hotspots in a national study, and shows how eight lanes, 45 mph speeds and crossings nearly a kilometer apart make deaths predictable rather than accidental. It is a vivid case study of the Stroad problem and of the crosswalk, signal, driveway and lane-removal fixes the Commonway System specifies.
    
    MED-107
    

[See all 3 in the Media Gallery](https://commonwaysystem.org/media/?for=RFT-CDR-07)

## Where this leads: Target patterns

-   [Bike Highway / Greenway](https://commonwaysystem.org/patterns/collectors/bike-highway-greenway.md) (COL-BHG-04)
-   [Default (Standard Collector)](https://commonwaysystem.org/patterns/collectors/default.md) (COL-DEF-01) with [Protected Bike Lane / Cycle Track](https://commonwaysystem.org/patterns/elements/protected-bike-lane-cycle-track.md) (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](https://commonwaysystem.org/guide/construction-methodology-spectrum.md).

## Who can move this

Usually a city or county public works decision, achievable through routine restriping maintenance in many cases. See [Legal & Planning Mechanisms](https://commonwaysystem.org/guide/legal-planning-mechanisms.md).

## Related retrofit strategies

-   [Protected bike lane retrofit via lane removal](https://commonwaysystem.org/retrofits/corridor/protected-bike-lane-lane-removal.md) (RFT-CDR-08)
-   [Protected bike lane retrofit via parking reduction](https://commonwaysystem.org/retrofits/corridor/protected-bike-lane-parking-reduction.md) (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.](https://store.transportation.org/Item/PublicationDetail?ID=4127)
2.  Evidence-based [Federal Highway Administration, "Separated Bike Lanes," Bicycle and Pedestrian Program.](https://www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/separated_bike_lanes/index.cfm)