What Are Speed Cushions? Complete 2026 Guide

A speed cushion is a traffic-calming device built like a speed hump but split into 2 or 3 segments, with wheel-track gaps wide enough for fire-truck axles to straddle. Cars hit the cushion full-on and slow to 15 to 20 mph. Fire trucks and ambulances ride through the gaps and hold 20 to 25 mph. The whole reason cushions exist: a speed hump on a fire-access route adds enough response-time delay that on a serious call it's the difference between a save and a loss. Below: the engineering, the use cases, and the design specs our crews build to.

What is a speed cushion?

A speed cushion is a series of 2 or 3 raised segments, each typically 6 feet by 6 feet by 3 inches tall, separated by wheel-track gaps approximately 6 feet wide. The total cushion device spans the full lane width. A passenger car cannot avoid hitting at least one segment with each wheel-track and is slowed by the contact. A fire truck with a wider axle straddles the segments and rides through the gaps without the vertical pulse a hump would deliver.

Why do speed cushions exist?

Single-purpose: emergency-vehicle compatibility. The Federal Highway Administration's Traffic Calming ePrimer documents fire-truck response-time delays of 5 to 10 seconds per speed hump. On a fire-response route with 4 or 5 humps, the cumulative delay can exceed 30 seconds. Speed cushions deliver most of the calming benefit (6 to 8 mph reduction in 85th-percentile passenger-car speed) with negligible fire-truck delay. The NFPA 1141 fire-access standard treats cushions as the device of choice on fire-response calming routes.

How Are Speed Cushions Different from Speed Humps?

Variable	Speed hump	Speed cushion
Footprint	Full lane width, 12 to 14 ft long	Full lane width, 6 to 7 ft long
Construction	Single continuous raised section	2 or 3 segments with wheel-track gaps
Passenger-car speed reduction	7 to 9 mph	6 to 8 mph
Fire-truck delay	5 to 10 seconds per hump	1 to 3 seconds per cushion
Bus impact	Moderate (lifts gurneys, jolts standees)	Lower (most buses straddle one gap)
Ambulance impact	High	Low
Material	Mostly asphalt	Asphalt or modular rubber
Cost per unit	$2,000 to $5,000+	$2,500 to $8,000+

The cost difference reflects the additional construction complexity -- forming and pouring 2 or 3 separate segments per cushion is more labor than a single hump.

Where Are Speed Cushions Used?

Five primary use cases.

1. Fire-access roads

The original use case. Any road that serves as a fire-response corridor and also needs calming -- residential greenways with fire-truck access, hospital-campus drives, school-zone fire lanes -- is a candidate. The Portland Fire Code and the Tualatin Valley Fire and Rescue access standards both recognize cushions as the preferred calming device on response routes.

2. Bus routes

A speed table is gentler for buses than a cushion, but cushions work where buses are infrequent and the corridor needs more calming than a table provides. Most TriMet, LTD, and Lane Transit routes can ride cushions without service issues.

3. Mixed-traffic streets

Streets that serve a mix of passenger cars, residential traffic, and delivery vehicles benefit from cushions because the wheel-track gaps reduce delivery-vehicle suspension wear and complaint volume.

4. Long residential corridors with fire-access requirements

A series of 3 or 4 cushions spaced 250 to 350 feet apart can calm a corridor without imposing the cumulative fire-truck delay of an equivalent hump series.

5. Hospital and emergency-services campuses

Internal calming on campuses where ambulance flow is constant. A cushion slows visiting cars to 15 mph without delaying ambulance arrivals at the ED entrance.

Speed Cushion Dimensions and Specifications

Variable	Recommended	Source
Segment length (travel direction)	6 to 7 ft	ITE Traffic Calming Manual
Segment width (across road)	5 to 6 ft	ITE / FHWA
Segment height	3 to 3.5 in	ITE / FHWA
Wheel-track gap width	5.5 to 6 ft	NFPA / fire-marshal
Number of segments per cushion	2 or 3 (lane width dependent)	Local jurisdiction
Profile	Parabolic	ITE
Material	Asphalt or modular rubber	Property choice
Marking	Yellow chevrons on each segment	MUTCD W17-1

The wheel-track gap dimension is the critical variable. Most U.S. fire trucks have an outside-axle width of 8 to 8.5 feet -- the gap must accommodate the axle width plus a 6-inch alignment margin. Cojo's design team confirms the local fire-truck axle dimension with the responding department before drawing the gap.

Types of Speed Cushions

Asphalt cast-in-place

Permanent installation. Crew forms each segment with a paving template, places hot-mix asphalt, compacts to grade, and shapes the parabolic profile. Lifespan 7 to 10 years on parking lots, 5 to 7 years on residential streets. Most common in Cojo's Portland-metro project work.

Modular rubber

Bolt-on units sized to the segment dimensions. Faster install (4 to 6 hours per cushion vs 1 to 2 days for asphalt), removable, and material-cost-only when the design needs adjustment. Lifespan 5 to 8 years before bolts and rubber sections fatigue. Common on private property where future flexibility matters.

Concrete cast-in-place

Niche use. Longer lifespan than asphalt (12 to 20 years) but harder to modify. Used on high-volume HOA entry roads where lifespan is the primary variable.

Marking and Signage Requirements

Per MUTCD Part 2C and the FHWA Traffic Calming ePrimer:

• Yellow chevron pattern on each segment face (6-inch stripes)
• W17-1 (HUMP) advance warning sign placed 100 to 200 feet ahead
• W17-1P advisory speed plaque showing the design speed
• Reflective markers on each segment edge
• HUMP advance pavement marking 50 to 100 feet upstream

Some jurisdictions use a custom CUSHION sign or marking instead of HUMP -- check the local agency's signage spec sheet.

How Effective Are Speed Cushions?

Effectiveness data from the FHWA CMF Clearinghouse and the ITE Traffic Calming Manual:

• Passenger-car speed reduction -- 6 to 8 mph (about 80 percent of an equivalent hump)
• Fire-truck delay -- 1 to 3 seconds (about 25 percent of an equivalent hump)
• Volume reduction -- 8 to 20 percent on the calmed segment
• Crash reduction -- 10 to 13 percent (close to humps)

Cushions trade about 1 mph of passenger-car speed reduction for 5 to 7 seconds of fire-truck delay savings per device. On any route where fire-truck delay matters, the trade is worth it.

Cojo's Tigard Cushion Install

In late 2025 Cojo installed a series of 3 asphalt speed cushions on a fire-access road in Tigard after the Tualatin Valley Fire and Rescue district flagged a proposed hump install as response-route incompatible. The corridor needed both calming (resident-petition driven) and uncompromised fire access. Pre-install 85th-percentile speeds were 28 mph; 60-day post-install measured 21 mph. TVF&R measured fire-truck delay through the cushion series at 5 seconds total (vs 25 to 30 seconds for an equivalent hump series).

Get a Speed Cushion Quote

If you are a fire marshal, traffic engineer, HOA board member, or property manager evaluating cushions vs humps, Cojo can provide a free site review. See the speed humps guide for the device-comparison context, speed cushion vs speed table for the table comparison, best speed cushions for product picks, speed cushion installation in Portland for a local example, or asphalt maintenance services for the install scope and pricing.

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