---
title: "Curb Extension"
url: "https://commonwaysystem.org/patterns/elements/curb-extension/"
id: "ELM-CBE-02"
description: "A widened curb that narrows the roadway at a crossing or parking zone, taking gateway, pinchpoint, chicane, bus bulb, or conventional form depending on its purpose and location."
updated: "2026-09-26"
---

# Curb Extension

`ELM-CBE-02`

Recommended Element

Curb Extension

A widened curb that narrows the roadway at a crossing or parking zone, taking gateway, pinchpoint, chicane, bus bulb, or conventional form depending on its purpose and location.

## 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

### [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.

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.

Aligned

### [This is the key to safer streets](https://www.youtube.com/watch?v=xsSp8gxzfjo)

Streetcraft

A full traffic-calming toolkit walkthrough, plastic mini-roundabouts, curb extensions, chicanes, the speed bump/hump/cushion/table family, and a Cincinnati road-diet case study with dramatic before/after crash data.

## Why this pattern exists

Narrowing the effective roadway width at a specific point shortens pedestrian crossing distance, slows turning and through vehicles, and can reclaim space for other uses (a bus stop, plantings, a parklet), addressing several distinct problems (crossing safety, traffic calming, space reclamation) with one flexible physical treatment.[1]

## Key considerations

-   Form should match purpose: a bus bulb needs a different length and clearance than a corner pinchpoint or a mid-block chicane[2]
-   Drainage design at the extension point needs attention, since it interrupts the normal curb and gutter line
-   Sightlines for both drivers and pedestrians should be checked at the extension, especially near a crossing, since the extension changes sightline geometry

## Related patterns

[Curb](https://commonwaysystem.org/patterns/elements/curb.md) (ELM-CRB-01), [Crosswalk](https://commonwaysystem.org/patterns/elements/crosswalk.md) (ELM-CRW-08) (typical pairing at a crossing); [Plaza/Parklet](https://commonwaysystem.org/patterns/facilities/plaza-parklet.md) (FAC-PLZ-07) (Facility pattern this often anchors); [Transit Boarding Island](https://commonwaysystem.org/patterns/elements/transit-boarding-island.md) (ELM-TBI-41) (a related but distinct treatment for transit stops); [Modal Filter / Point Closure](https://commonwaysystem.org/patterns/elements/modal-filter-point-closure.md) (ELM-MFP-44) (an alternative geometry for narrowing or partially closing a street), [Median Island](https://commonwaysystem.org/patterns/elements/median-island.md) (ELM-MDI-45) (a center-of-roadway rather than lateral narrowing approach)

## References

1.  Precedent-based [NACTO Urban Street Design Guide, "Curb Extensions." Crossing-distance reduction and sizing guidance (length at least the crosswalk width, 1-2 ft narrower than the parking lane).](https://nacto.org/publication/urban-street-design-guide/street-design-elements/curb-extensions/)
2.  Evidence-based [Federal Highway Administration, "Install Curb Extensions at the Crosswalk" (Uncontrolled Pedestrian Crossing Treatment sheet). Identifies crash history, vehicle/pedestrian conflict, and speeding as the conditions this treatment addresses.](https://toolkits.ite.org/uiig/treatments/64%20Curb%20Extensions.pdf)