A speed bump is a raised pavement section, typically 3 to 4 inches tall and 1 to 3 feet long in the direction of travel, installed to force drivers down to about 5 mph. Bumps live on parking lots, driveways, and other private-traffic areas. The ITE Traffic Calming Manual finds speed bumps cut average speeds by 22 to 40 percent — the most aggressive vertical-deflection device in traffic-calming design.
Below: the definition, how a bump differs from related devices, and where it belongs (and where it doesn't). For a deeper buyer's guide, see What Are Speed Bumps? Complete 2026 Buyer's Guide.
What is the technical definition of a speed bump?
The Federal Highway Administration Traffic Calming ePrimer defines a speed bump as a raised pavement device with a parabolic or rounded cross-section, less than 6 inches tall and less than 3 feet long in the direction of travel, intended to slow vehicles to 5 mph or less in low-speed environments. The ITE specification published in the Traffic Calming Manual narrows the standard further: 3 to 4 inches tall, 1 to 3 feet long, with an approach taper that produces vertical deflection without damaging vehicle suspensions.
Three elements make a raised pavement section a speed bump:
- Height: 3 to 4 inches above the surrounding surface
- Length in the direction of travel: 1 to 3 feet
- Cross-section: parabolic, rounded, or trapezoidal -- not a sharp ridge
A pavement section that exceeds 4 inches in height or 3 feet in length is no longer a speed bump. It becomes a speed hump (longer) or a speed table (longer and flat-topped). See speed bump vs speed hump for the comparison.
What is a speed bump used for?
Speed bumps exist for one purpose: to slow vehicle traffic in environments where signs and stop controls are not enough. The most common applications:
- Commercial parking lots: retail centers, office complexes, medical campuses
- Apartment complexes and HOA communities: enforcing posted 5 mph private-road limits
- School parking lots: pickup-and-drop-off lanes
- Drive-thru lanes: pacing customers at order windows and pickup windows
- Warehouses and distribution centers: forklift-aisle protection (paired with wheel stops)
- Residential driveways: where private property meets a public sidewalk
According to ITE field studies cited in the Traffic Calming Manual, speed bumps installed at correct spacing achieve a 22 to 40 percent reduction in 85th-percentile speeds. Cojo installed eight rubber speed bumps on a 60,000-square-foot Tualatin distribution center in February 2026; pre-and-post radar measurements showed average forklift-aisle vehicle speeds fell from 18 mph to 7 mph.
Where should speed bumps NOT be used?
Speed bumps are inappropriate in three settings:
1. Public residential streets
Public streets carry buses, fire trucks, and ambulances at speeds of 25 to 35 mph. A 3-inch-tall, 2-foot-long speed bump at 25 mph produces a violent impact that damages emergency-vehicle equipment. Public residential streets use speed humps (12 to 14 feet long) or speed cushions (split-design with wheel-track gaps for fire trucks).
2. Fire-access lanes
NFPA 1141 and most local fire codes prohibit solid speed bumps on designated fire-apparatus access roads. Use a speed cushion instead, which lets ladder trucks straddle the device with their wheel tracks.
3. Streets with city-owned bus routes
TriMet, Lane Transit District, and most municipal transit authorities require speed tables (22 feet long, flat-top) instead of bumps on bus routes. The longer flat-top profile lets buses ride at 20 mph without passenger discomfort.
How does a speed bump compare to similar devices?
| Device | Length | Target Speed | Best Use |
|---|---|---|---|
| Speed bump | 1 to 3 ft | 5 mph | Parking lots, driveways |
| Speed hump | 12 to 14 ft | 15 to 20 mph | Residential streets |
| Speed cushion | 6 ft (with wheel gaps) | 10 to 15 mph | Fire-access streets |
| Speed table | 22 ft (flat top) | 20 to 25 mph | Bus routes, mid-block crossings |
| Rumble strip | 12 to 18 in (audible only) | Alert, not slow | Highway approaches |
What materials are speed bumps made from?
Modern speed bumps are manufactured from four primary materials:
Rubber (recycled tire)
Modular rubber sections (4-foot, 6-foot, 8-foot, and 10-foot lengths) bolt to the pavement with concrete anchors or asphalt-anchor spikes. Rubber bumps install in 60 to 90 minutes per unit, can be unbolted seasonally, and last 3 to 5 years in Oregon climate.
Asphalt
Asphalt speed bumps are formed and screeded as part of a paving operation. They are permanent, last 7 to 10 years, and require a paving crew with a hot-mix-asphalt source. Cojo's most-installed asphalt bump on a Beaverton retail center in 2025 used a 12-foot-long form, 3.5 inches tall, with chevron paint and reflective tape applied after cure.
Concrete
Precast concrete bumps anchor with steel pins and grout. They last 15 to 25 years but are brittle in Oregon freeze-thaw cycles. See concrete vs asphalt speed bump for the climate-driven trade-off.
HDPE plastic
Lightweight, low-cost, and easy to install -- but plastic snaps in cold weather and degrades under UV. Best for short-term or seasonal use. Permanent Oregon installs almost always switch to rubber or asphalt within two years.
For full pricing, see How Much Do Speed Bumps Cost?.
How are speed bumps marked and signed?
A correctly installed speed bump carries three visual elements:
- Yellow-and-black chevron pavement marking across the bump face (6-inch stripes, 45-degree angle)
- Reflective tape on the bump face for night visibility
- Advance-warning sign placed 100 to 200 feet before the bump (MUTCD W17-1 "Bump" sign)
The Manual on Uniform Traffic Control Devices does not formally adopt speed bumps as a traffic-control device, but the chevron pattern and W17-1 sign are near-universal industry practice. For Oregon-specific marking rules, see speed bump marking requirements.
Are speed bumps required to follow a code?
For public streets, yes -- jurisdictions such as Portland (PBOT) and Salem Public Works require traffic studies, neighborhood petitions, and engineering review before installing any speed bump or hump. For private parking lots, no -- property owners can install speed bumps without city approval, but ADA-compliant pathways must be preserved and bumps cannot block fire-access lanes per International Fire Code Section 503.
In Oregon, Cojo's commercial installs follow ITE Traffic Calming Manual specifications, the Oregon Department of Transportation Traffic Calming Guidelines, and the local jurisdiction's parking-lot-improvement standards (Salem Chapter 79, Portland Title 33.266).
Cost of installing a speed bump
Industry Baseline Range for a single installed parking-lot speed bump:
| Item | Industry Baseline Range |
|---|---|
| Rubber speed bump (6-ft unit, installed) | $280 to $1,000+ |
| Asphalt speed bump (single, formed and poured) | $300 to $1,500+ |
| Concrete speed bump (single, precast set) | $400 to $2,000+ |
| Plastic speed bump (single, low-traffic) | $40 to $250 |
Current Market Reality
2026 commercial-install pricing in the Salem-Portland-Eugene corridor runs higher than baseline because of fuel surcharges, prevailing-wage labor, and added traffic-control mobilization costs.