What Is a Speed Cushion? 2026 Definition & Purpose

A speed cushion is a vertical-deflection traffic-calming device split into 2 to 4 segments with wheel-track gaps sized to fire-apparatus axle width, so fire engines and ambulances can straddle the device while passenger cars hit the segments and slow to 18 to 22 mph. The Federal Highway Administration's Traffic Calming ePrimer Module 3.4 defines the device, and the Institute of Transportation Engineers (ITE) Traffic Calming Manual, Chapter 3, sets the dimensional standards. Cushions are the preferred traffic-calming tool on fire-access streets.

What Is a Speed Cushion?

A speed cushion consists of:

• 2 to 4 raised pavement segments, typically 6 feet long by 6 feet wide by 3 to 3.5 inches tall each
• Wheel-track gaps between the segments, sized to local fire-apparatus rear-axle width (commonly 1.6 to 1.85 meters / 63 to 73 inches, sometimes 80+ inches for North American Type 1 engines)
• Total cushion footprint typically 13 to 18 feet across the travel lane

The defining feature is the wheel-track gap. A vertical-deflection device without wheel-track gaps is a speed bump (under 3 feet long) or a speed hump (12 to 14 feet long), not a speed cushion.

Why Were Speed Cushions Invented?

Speed cushions emerged in northern Europe in the 1990s as a response to fire department objections against speed humps on residential streets. Fire departments documented unacceptable response delays caused by traditional vertical-deflection devices: speed humps slowed fire engines to 8 to 12 mph, adding 5 to 9 seconds of delay per device. On a residential street with three humps, total response delay reached 15 to 27 seconds; on streets with five or more devices the delays reached a minute or more.

The cushion design solves the conflict. By splitting the device into segments with gaps sized to fire-apparatus axle width, designers preserved the speed-reduction effect on passenger cars while letting fire trucks straddle the device with one tire path through each gap. Fire-truck delay drops from 5 to 9 seconds to under 2 seconds per cushion.

The Federal Highway Administration imported the device into US practice in the early 2000s and codified it in the Traffic Calming ePrimer.

What Is the Purpose of a Speed Cushion?

Three jobs:

1. Slow passenger cars to 18 to 22 mph at the cushion (85th-percentile speed)
2. Preserve emergency-vehicle access by letting fire trucks and ambulances straddle the device
3. Allow transit buses to maintain near-normal operating speeds because most North American bus axle widths match fire-apparatus widths

The combination of these three jobs is what makes cushions different from any other vertical-deflection device.

Where Are Speed Cushions Used?

Use case	Why cushions fit
Residential fire-access streets	Preserves apparatus access while calming traffic
Hospital service roads	Ambulance and patient-transport vehicle access
School zones with bus routes	Bus delay stays under 3 seconds per cushion
Neighborhood greenways on EMS corridors	Combines pedestrian/bike priority with emergency response
University campus loops	Many campuses have internal fire-access requirements
Hotel and resort access roads	Where fire access overlaps with guest traffic calming

Speed cushions are not used in:

• Parking lots (use rubber speed bumps instead, no fire-access conflict)
• Highway interchanges (speeds too high for any vertical-deflection device)
• Streets with no fire-access constraint (speed humps are cheaper and produce more speed reduction)

For dimensional detail see speed cushion dimensions, and for engineering background see how do speed cushions work.

How Do Speed Cushions Compare with Speed Bumps and Humps?

Device	Length (travel)	Use case	Fire-truck delay
Speed bump	1 to 3 feet	Parking lots only	6 to 10 seconds (severe)
Speed hump	12 to 14 feet	Residential streets without fire-access concern	5 to 9 seconds
Speed cushion	6 to 7 feet per segment with gaps	Fire-access, EMS, transit corridors	Under 2 seconds
Speed table	22 feet	Streets with marked crosswalks or transit routes	2 to 4 seconds

For the cushion-versus-table comparison see speed cushion vs speed table.

What Materials Are Speed Cushions Made From?

Material	Lifespan	Best fit
Modular rubber	7 to 10 years	Most residential and fire-access installs
Asphalt cast-in-place	12 to 18 years	Long-term residential greenways
Polyurethane / plastic	4 to 7 years	Pilot programs, short-term installs
Concrete	25 to 35 years	Industrial and hospital service roads

Modular rubber is the most common North American configuration because it is removable for repaving and matches the modular wheel-track-gap geometry without custom forming. Asphalt cast-in-place is permanent and lower lifecycle cost on streets where the design is stable.

Are Speed Cushions Approved in Oregon?

Yes. All Tier 1 Oregon cities (Portland, Salem, Eugene, Springfield) have included speed cushions in their residential traffic-calming program menus. Tier 2 cities (Bend, Beaverton, Hillsboro, Gresham, Corvallis, Albany, Medford) have approved cushions on a case-by-case basis. Local fire departments review wheel-track gap dimensions before installation.

The Portland Bureau of Transportation Neighborhood Greenways and Traffic Calming program is the most prolific Oregon user of speed cushions; PBOT has installed cushions on dozens of greenway corridors that overlap with fire-access routes. Eugene Public Works pairs cushion installs with Vision Zero priority corridors on streets with bus and EMS service.

From Our Crew

On a Tigard fire-access greenway in late 2024, Cojo installed a set of three modular rubber speed cushions for Tualatin Valley Fire & Rescue. The wheel-track gap was specified at 1.85 meters from the department's tower-truck axle measurement. Post-install drive-through delay measured by the department was 1.8 seconds per cushion at code-3 response. The same corridor with traditional speed humps would have produced 18 to 27 seconds of delay across three devices. The cushion configuration was the only design that preserved response time while still calming passenger-car speeds.

What Reference Documents Define Speed Cushions?

• ITE Traffic Calming Manual, Chapter 3 (Speed Cushions section)
• FHWA Traffic Calming ePrimer, Module 3.4
• NFPA 1141, Chapter 5 (fire-protection infrastructure for residential development)
• IFC Section 503 (fire-apparatus access roads)

Always verify current requirements with your local jurisdiction. This article reflects May 2026 published guidance.

Need a Speed Cushion for Your Street?

Cojo provides speed cushion installation across the Oregon I-5 corridor. We coordinate fire-marshal review and dimensional sign-off, traffic-calming application packets, and installation in one scope. See the speed cushions guide for the broader product context, speed cushion dimensions for spec detail, and how do speed cushions work for engineering background. For Portland-area installs see Speed Cushion Installation Portland or pair the install with our asphalt maintenance services. Get a custom quote.

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