A speed cushion is a split-hump design with two raised pads separated by a wheel-track gap (typically 1.85 m, matching common ladder-truck axles). Cars hit both pads and slow to 15 to 20 mph; fire trucks straddle the gap and maintain 25 mph. A speed hump is a continuous device that affects every vehicle equally. If maintaining emergency-vehicle response time matters on the street, install a cushion. If a 6 to 8 second delay per fire truck is acceptable, a hump costs less and works fine.
Quick comparison
| Specification | Speed Hump | Speed Cushion |
|---|---|---|
| Geometry | Continuous parabolic, full lane width | 2 or 3 separated pads with wheel-track gaps |
| Pad length | 12 to 14 ft | 6 ft typical |
| Pad width | Full lane (10 to 12 ft) | 6 to 7 ft each |
| Wheel-track gap | None | 1.85 m (6 ft) typical |
| Fire-truck speed | 10 to 12 mph | 20 to 25 mph |
| Car speed | 15 to 20 mph | 15 to 20 mph |
| Cost (installed) | $1,500 to $5,000 | $2,500 to $8,000 |
| Best fit | Streets where fire response is not the priority | Fire-access roads, bus routes |
What is the difference between a speed hump and a speed cushion?
The cushion has gaps; the hump does not. A typical 6-foot-wide speed cushion pad is positioned so a passenger car (track width roughly 60 inches) cannot pass between two pads without crossing one of them. A fire truck (track width roughly 80 inches) can straddle the gap, putting its tires on the pavement between or alongside the pads. Cars get slowed; fire trucks pass at speed.
The Institute of Transportation Engineers (ITE) Traffic Calming Manual Chapter 3 describes cushions as "modified speed humps with wheel cutouts to allow large emergency vehicles to traverse with minimal speed reduction." The Federal Highway Administration's Traffic Calming ePrimer documents 5 to 10% greater fire-response performance for cushions compared to humps on the same street (FHWA ePrimer).
When does fire-truck access matter enough to choose a cushion?
Three conditions trigger the cushion choice:
- The fire marshal designates the street as primary access. Most Oregon cities maintain a primary-response-route map. If the street appears on it, the local fire bureau typically requires cushions over humps. NFPA 1141 (Standard for Fire Protection Infrastructure for Land Development) and the International Fire Code Section 503 govern this analysis.
- Cardiac-arrest call volume is concentrated in the area. The American Heart Association's resuscitation guidelines link survival to response time; departments push for cushions where call volume is high.
- Mutual-aid response routes use the street. Some streets serve as connectors between districts where neighboring departments respond. Mutual-aid agreements often spec cushions on these routes.
In a 2025 install on a Tigard collector that runs between two TVF&R stations, our crew specified four 6-foot rubber cushions over the equivalent four asphalt humps. The cost premium was roughly $4,000 across the four units; the fire chief signed off the same week.
When is a speed hump the better choice?
Humps win on three criteria: cost, simplicity, and effectiveness for cars. If fire-response time is not a flagged concern, the hump's full-lane geometry slows traffic more reliably than a cushion (some drivers learn to weave between cushion pads, which the hump prevents).
Specifically, choose a hump when:
- The street is not on a fire primary-response map.
- Bus service is absent (transit agencies typically prefer tables, not cushions or humps).
- Budget is tight and the street has 3+ devices planned (the per-unit savings compound).
- Driver weaving is a known problem in the neighborhood.
For the full hump walkthrough, see the speed humps guide.
What does NFPA 1141 say about speed humps and cushions?
NFPA 1141 references "fire apparatus access roads" and gives jurisdictions latitude to approve traffic-calming devices that do not impede operations. The standard does not name speed cushions specifically, but local fire codes have widely adopted the cushion-over-hump preference. Portland Fire and Rescue, Tualatin Valley Fire and Rescue, Salem Fire, and Eugene-Springfield Fire & EMS have all published guidance favoring cushions on primary apparatus routes.
When in doubt, send the device choice to the fire marshal for sign-off before pavement work begins. A retroactive removal because the fire bureau objects is far more expensive than the original install delta.
How much do speed humps and cushions cost compared?
Industry Baseline Range
| Component | Speed Hump | Speed Cushion (3-pad) |
|---|---|---|
| Material (asphalt or modular rubber) | $400 to $1,200 | $800 to $2,800 |
| Labor (crew + traffic control) | $900 to $3,200 | $1,400 to $4,600 |
| Pavement marking + signage | $200 to $600 | $300 to $900 |
| Installed total | $1,500 to $5,000 | $2,500 to $8,000 |
Current market reality
Cushions run 50 to 70% more than humps because the geometry is more complex (three discrete pads with consistent wheel-track gaps require precise layout) and because modular rubber units (the dominant cushion product) cost more per pound than hot-mix asphalt. The cost gap closes on multi-unit projects; a four-cushion install on the same street drops the per-unit premium by 15 to 20%.
What do drivers experience differently?
Drivers feel a hump as a single rolling rise; the suspension articulates once. Drivers feel a cushion as two distinct pad strikes (left tires on one pad, right tires on another) with a brief flat between. The cushion ride is slightly less comfortable for cars but feels nearly identical to a hump at the target 15 to 20 mph speed range.
Some drivers learn to position one wheel in the cushion's wheel-track gap, halving the slowing effect. Cushions paired with chevron-painted asymmetric pad layouts ("staggered cushions") prevent this; the staggered geometry means at least one tire always crosses a pad regardless of weave path.
Frequently asked questions
Can a speed cushion replace a speed hump on any street? Almost any street, but verify with the local fire marshal first. Cushions perform slightly worse than humps for car-only slowing because of the weave-around risk. On streets with no fire-response priority, the hump is usually the right device.
Do speed cushions slow cars as much as speed humps? Roughly the same target speed (15 to 20 mph) when the cushion pads are properly sized. Field studies show humps deliver 1 to 3 mph more speed reduction on average, mainly because cushions allow some weave-around behavior.
Are speed cushions more expensive than speed humps? Yes. Cushions run 50 to 70% more on a per-unit basis. The premium narrows on multi-unit projects.
Will a fire chief approve a speed hump on a primary access road? Sometimes, but most Oregon fire bureaus prefer cushions on flagged routes. A retroactive change is expensive; coordinate with the fire marshal before the install.
Do speed cushions require special permits? The same permits as speed humps: city traffic-calming program approval (or HOA authorization on private streets), plus fire-marshal review where applicable.
Get a Site-Specific Recommendation
Cojo installs speed humps, cushions, and tables across Oregon, with fire-marshal coordination built into our process. Contact Cojo for a site walk and device recommendation, or learn more about our asphalt paving services.