Curb Extension
ELM-CBE-02 Curb Extension
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#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 chicane2
- 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 (ELM-CRB-01), Crosswalk (ELM-CRW-08) (typical pairing at a crossing); Plaza/Parklet (FAC-PLZ-07) (Facility pattern this often anchors); Transit Boarding Island (ELM-TBI-41) (a related but distinct treatment for transit stops); Modal Filter / Point Closure (ELM-MFP-44) (an alternative geometry for narrowing or partially closing a street), Median Island (ELM-MDI-45) (a center-of-roadway rather than lateral narrowing approach)
#References
- 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).(opens in new tab)
- 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.(opens in new tab)