---
title: "Lane diet"
url: "https://commonwaysystem.org/retrofits/corridor/lane-diet/"
id: "RFT-CDR-03"
description: "Narrows existing travel lane widths without removing a lane, reclaiming the width difference for a bike lane, wider sidewalk, or buffer."
updated: "2026-10-18"
---

RFT-CDR-03

# Lane diet

Narrows existing travel lane widths without removing a lane, reclaiming the width difference for a bike lane, wider sidewalk, or buffer.

## Strategy viewer

Illustration in progress

No illustration of Lane diet has been made yet. Interactive views are planned for every pattern and Retrofit Strategy.

## Overview

Where a road diet removes a whole lane, a lane diet keeps the same lane count but makes each lane narrower, typically down to 10 or 10.5 feet from a wider original width. This is a lighter-touch alternative, useful where traffic volume doesn't support removing a lane but the existing lanes are wider than necessary for safe operation.

## 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.

Aligned

### [The Airtight Case for Road Diets](https://usa.streetsblog.org/2014/10/29/the-airtight-case-for-road-diets)

Streetsblog USA

The article lays out the evidence for four-to-three lane conversions, citing FHWA data showing 20 to 50 percent crash reductions with minimal capacity effects. It is the evidence summary behind the Commonway System's four-to-three road diet retrofit strategy.

MED-047

Aligned

### [Fabulous Ferndale (Ep 436)](https://theoverheadwire.com/2023/06/unedited-podcast-transcript-436-fabulous-ferndale/)

The Overhead Wire

Ferndale, Michigan's mayor describes the city's road diet of eight-lane Woodward Avenue and the practical politics of working with the state DOT. It is a practitioner-level case study for the Commonway System's road diet strategies.

MED-065

## Where this leads: Target patterns

-   [Default (Standard Collector)](https://commonwaysystem.org/patterns/collectors/default.md) (COL-DEF-01)
-   [Default (No Parking, No Direct Access)](https://commonwaysystem.org/patterns/arterials/default.md) (ART-DEF-01)

## Applicability and thresholds

Appropriate on corridors where lane count must stay the same, due to volume or a jurisdiction's unwillingness to remove a lane, but where existing lanes exceed the width actually needed for safe operation at the corridor's design speed.

## Evidence and effectiveness

A Canadian Institute of Transportation study presented in 2015 found side-impact and turn-related crash rates lowest where average lane widths fall between 10 and 10.5 feet, challenging the assumption that wider lanes are inherently safer.[1]

## Getting it built

Can move through the construction spectrum easily, since restriping to a narrower lane width is typically a paint-only change, well suited to a demonstration or pilot stage before permanent striping. See [Construction Methodology & The Build Spectrum](https://commonwaysystem.org/guide/construction-methodology-spectrum.md).

No formal decision process is typically required, since lane count is unchanged.

## Who can move this

Usually a city or county public works decision, achievable through routine restriping without new legislation. See [Legal & Planning Mechanisms](https://commonwaysystem.org/guide/legal-planning-mechanisms.md).

## Related retrofit strategies

-   [Four-to-three lane road diet](https://commonwaysystem.org/retrofits/corridor/four-to-three-lane-road-diet.md) (RFT-CDR-01) (the more aggressive alternative where lane count itself can be reduced)

## References

1.  Evidence-based [Findings presented at the Canadian Institute of Transportation Engineers annual meeting, June 2015, on lane width and side-impact/turn-related crash rates, as referenced in "Technical Guidance on Road Diets."](https://www.pps.org/article/technical-guidance-on-road-diets)