Speed humps on residential streets are typically spaced 250 to 500 feet apart, with 300 feet as the most common U.S. residential default. Spacing depends on the target speed, the street's pre-install 85th-percentile speed, and the available street length. Closer spacing forces drivers to maintain a sustained low speed; wider spacing lets drivers re-accelerate between humps. The Institute of Transportation Engineers (ITE) Traffic Calming Manual Chapter 3 provides spacing-to-target-speed charts that most U.S. traffic-calming programs follow.
Spacing-to-target-speed reference
| Target 85th-percentile speed | Recommended hump spacing |
|---|---|
| 15 mph | 200 to 280 ft |
| 20 mph | 280 to 380 ft |
| 25 mph | 380 to 500 ft |
| 30 mph | not recommended (use larger device) |
Why does spacing matter?
The spacing problem is the acceleration window. A driver who slows to 15 mph at one hump will re-accelerate as soon as they pass it. The question is how fast they can climb back to highway speed before the next hump. ITE field studies referenced in the Traffic Calming Manual document the relationship: at 280 ft spacing, drivers cannot climb above 22 to 25 mph before the next hump. At 500 ft spacing, drivers regularly hit 30+ mph between humps, partially defeating the slowing purpose.
For streets where the goal is sustained 15 to 20 mph speeds, 250 to 380 ft spacing delivers the result. For streets where occasional slowing to 15 mph is the goal but 25 to 30 mph between humps is acceptable, wider spacing works.
What is the standard spacing in Oregon cities?
Oregon city traffic-calming programs typically default to 300 ft spacing on residential collectors. Specific city standards:
| City | Standard Spacing |
|---|---|
| Portland (PBOT) | 250 to 350 ft |
| Salem | 300 to 400 ft |
| Eugene | 300 to 400 ft |
| Beaverton | 280 to 380 ft |
| Bend | 300 to 400 ft |
| Corvallis | 300 to 400 ft |
How do you decide spacing for a specific street?
Three steps:
- Measure pre-install 85th-percentile speed. A 24-hour spot-speed survey tells you what speeds drivers naturally choose. The 85th-percentile is the standard reference (the speed below which 85% of drivers travel).
- Set a target post-install speed. Most residential targets are 5 to 10 mph below pre-install 85th. A street with 35 mph pre-install gets a 25 mph target; a street with 30 mph pre-install gets a 20 mph target.
- Pick spacing from the ITE chart. Match the target speed to the recommended spacing range.
In a 2025 install on a Beaverton residential collector, our crew measured pre-install 85th-percentile of 32 mph. Target post-install speed was 22 mph (10 mph reduction). The ITE chart pointed to 300 to 380 ft spacing; the city traffic engineer specified 320 ft. Three humps across a 960-ft street segment delivered the design.
Where do you place the first and last humps?
Two rules:
- First hump 100 to 200 ft from the upstream entrance. Far enough that drivers see and respond, but close enough that they cannot accelerate to highway speed first.
- Last hump 100 to 200 ft from the downstream exit. Symmetric reasoning.
If the street is shorter than 600 ft, two humps placed at the third points (one-third and two-thirds along the length) work. Streets shorter than 400 ft typically receive only one hump or none at all; shorter streets do not give drivers room to accelerate enough to need calming.
How does spacing interact with intersection locations?
Speed humps should not be placed:
- Within 100 ft of a stop sign or signal. Drivers are already slowing to stop; a hump within the slowing zone creates compound braking.
- Within 50 ft of a curve. Drivers braking on a curve risk loss of traction.
- Within 25 ft of a driveway. Driveway entrances need clear pavement for the turn-in.
Adjust spacing to avoid these conflicts. On streets with frequent intersections or driveways, the practical spacing tightens to whatever clear pavement exists between obstructions.
What about spacing on through-streets versus dead-ends?
Through-streets need consistent spacing across the full segment. Dead-end streets need spacing only on the approach segment; the dead-end itself does not need a hump because drivers naturally slow as they approach.
For cul-de-sac access streets, two humps placed before the cul-de-sac (one at the upstream entrance, one halfway along) typically deliver the slowing target. The ITE chart spacing applies to the spacing between the two humps, not the spacing from the cul-de-sac end.
Frequently asked questions
How far apart should speed humps be on a residential street? 250 to 500 ft typical, with 300 ft as the most common default. Use the ITE Traffic Calming Manual Chapter 3 spacing-to-target-speed chart.
Can speed humps be placed too close together? Yes. Below 200 ft spacing, drivers complain about constant slowing and the hump series loses public support. Below 150 ft spacing, the hump series becomes a chicane-style obstruction.
Do all city programs use the same spacing standard? Most Oregon cities follow the ITE guidance with minor variations. Check the city's standard detail or traffic-calming program spec for the exact range.
What happens if I install only one speed hump? Single humps deliver local slowing at the device but drivers re-accelerate quickly afterward. For streets where the goal is a single problem location (e.g. a school crosswalk), one hump can be effective. For sustained slowing along a segment, multiple humps are required.
Can spacing change along the same street? Yes. Some streets have a fast segment that needs tight spacing and a slower segment that needs wide spacing. Variable spacing within a single project is common; the ITE chart applies to each segment independently.
Plan Compliant Spacing
Cojo installs multi-unit speed-hump projects across Oregon with ITE-compliant spacing and city standard-detail matching. Contact Cojo for a site assessment, or see the speed humps guide for full options.