A speed hump is a raised pavement section, 12 to 14 feet long in the direction of travel and 3 to 4 inches tall at the crown, sized to slow passenger vehicles to 18 to 20 mph without the harshness of a speed bump. Most are built from asphalt and used on residential streets, school zones, and slow-speed commercial roads where calming matters but emergency-vehicle access still has to work. Below: the definition, how a hump differs from related calming devices, and where it fits.
What is a speed hump in plain English?
A wide, gentle bump in the road. The "hump" name describes the parabolic curve -- it rises gradually for the first 6 to 7 feet, peaks in the middle, and descends gradually over the back 6 to 7 feet. Cars traversing the hump at the design speed (15 to 20 mph) feel a soft swell rather than the sudden jolt of a speed bump.
What is the purpose of a speed hump?
Three primary purposes:
- Lower vehicle speeds on calming-target streets to 18 to 20 mph
- Reduce traffic volume by discouraging cut-through driving
- Improve pedestrian and resident safety without restricting access for residents themselves
The Federal Highway Administration's Traffic Calming ePrimer is the source document most U.S. agencies cite for the standard purpose statement.
What Are the Standard Dimensions of a Speed Hump?
| Dimension | Range | Source |
|---|---|---|
| Length (direction of travel) | 12 to 14 feet | ITE Traffic Calming Manual |
| Height at crown | 3 to 4 inches | FHWA ePrimer |
| Width across road | Full lane (typically 10 to 12 feet) | Local jurisdiction |
| Profile | Parabolic | ITE recommended |
| Approach taper | Smooth, no flat top | ITE recommended |
What Is a Speed Hump Made Of?
The dominant material is hot-mix asphalt -- the hump is essentially a paved-in raised section continuous with the surrounding road. Other materials:
- Asphalt -- 85 percent of installs Cojo handles. Permanent, low-profile, blendable with the road
- Rubber (modular) -- bolt-on units typically 12 to 14 feet long. Used on private property where future removal may matter
- Concrete (cast-in-place) -- niche use; longer-lasting but harder to modify or remove
- Plastic -- light-duty, residential driveway scope only
The choice depends on permanence, maintenance flexibility, and whether the surface needs to flex with seasonal pavement movement. Asphalt is the default for residential street programs.
Where Are Speed Humps Used?
Speed humps fit four common contexts.
Residential streets
The most common installation. A street with a 25-mph posted speed and 85th-percentile speeds in the 28 to 32 mph range is a textbook speed-hump candidate. Most municipal traffic-calming programs require a petition from residents, a city traffic study confirming speeds, and an emergency-services review.
School zones
20-mph school speeds align well with the 18 to 20 mph design speed of a hump. The Oregon DOT school-zone guidance treats humps as one of several allowed calming devices for school-frontage roads.
Low-speed commercial properties
Apartment-complex driveways, retail parking-lot circulation lanes, medical campuses, and college parking-lot perimeter roads. Cojo installs about half its annual hump volume on commercial property where there is no city approval gate.
Private roads and HOAs
HOA-controlled private streets with no city involvement. Decisions are made by the HOA board under Oregon Revised Statutes Chapter 94 (Planned Communities).
How Is a Speed Hump Different from a Speed Bump?
Length is the defining variable. The speed bump vs speed hump reference covers the full comparison, but the short version:
| Variable | Speed bump | Speed hump |
|---|---|---|
| Length (travel direction) | 1 to 3 feet | 12 to 14 feet |
| Height | 3 to 4 inches | 3 to 4 inches |
| Design speed | 5 to 10 mph | 15 to 20 mph |
| Used on | Parking lots, driveways | Residential streets, school zones |
| Material | Mostly rubber | Mostly asphalt |
| Emergency-vehicle penalty | High | Moderate |
How Is a Speed Hump Different from a Speed Cushion?
A speed cushion is a hump split into segments with wheel-track gaps wide enough for fire-truck axles to straddle. The hump slows passenger cars; the gaps let emergency vehicles maintain speed. The speed cushions guide covers the full detail. Use a cushion when fire-access response time is a constraint.
How Is a Speed Hump Different from a Speed Table?
A speed table is a flat-topped raised section, typically 22 feet long, with 3-foot ramps on each end and a 16-foot flat in the middle. Tables are gentler than humps and let buses ride at 20 to 25 mph without rocking. Use a table on bus routes or where the calmed corridor must accommodate transit.
Cojo's Salem Speed Hump Install
In October 2025 Cojo installed a 12-foot parabolic asphalt speed hump on a private driveway in West Salem serving a 96-unit apartment complex. Pre-install 85th-percentile speeds at the building entrance averaged 24 mph; 60 days after install they averaged 17 mph, with no resident vehicle damage complaints over the same window. The full case is referenced on the speed hump installation in Salem page.
Get the Right Calming Device for Your Site
If you are evaluating whether a speed hump fits your street, parking lot, or campus, start with the speed humps guide for the full design context, or send Cojo a site photo for a free desk review. Cojo installs and maintains speed humps, cushions, and tables across Oregon -- see asphalt maintenance services for the install scope and pricing baseline.