Speed Humps for School Zones: Specification Guide (2026)

A school-zone speed hump is a 12-foot parabolic raised pavement section, 3 inches tall at the crown, sized for a 20-mph school-zone speed and built with bus clearance baked in. Done right, it knocks 85th-percentile speeds down 7 to 9 mph in the calmed segment without forcing buses to bottom out or slow below their service threshold. Below: the spec, the bus-route design constraint, and the school-board approval process we run with Oregon districts.

Are speed humps appropriate for school zones?

Yes -- and they are one of the most-deployed school-zone calming devices nationwide. The Oregon DOT school-zone guidance treats speed humps as an approved device for residential streets fronting schools, drop-off loops, and parent pickup lanes, provided the design accounts for bus and emergency-vehicle access. The Federal Highway Administration's Safe Routes to School materials reinforce humps as a recommended calming device near elementary and middle schools.

Why Choose a Speed Hump for a School Zone?

Three reasons humps win over bumps in school applications:

• Design speed matches the 20-mph school zone -- a 12-foot parabolic hump targets the same speed schools post on the W11-1 / S5-1 signage
• Buses can traverse safely -- a properly profiled hump slows buses by about 5 mph but does not lift gurneys, harm passengers, or damage suspension
• Lower complaint volume than bumps -- parents drop off and pick up daily; a harsh bump generates 5 to 10 times the complaint volume of a smooth hump

Specification for School-Zone Speed Humps

Variable	Recommended	Why
Length (travel direction)	12 ft	Targets 20-mph design speed
Height at crown	3 in	Bus clearance and 20-mph compatible
Profile	Parabolic	Smooth ride for buses and passenger vehicles
Width across roadway	Full lane (12 ft typical)	Prevents driver swerving around the hump
Material	Hot-mix asphalt	Permanent and matches surrounding pavement
Marking	Yellow-and-black chevrons	MUTCD W17-1 advance warning

The 3-inch crown height is the key trade-off. A 4-inch hump is more effective at slowing cars but creates a meaningful issue for buses and ambulances; a 2-inch hump is too gentle to register on a 20-mph design speed.

Bus Clearance Design

School buses have lower ground clearance than most municipal vehicles -- typically 11 to 13 inches at the rear axle differential and 8 to 10 inches at the front bumper. A 3-inch parabolic hump traversed at 15 mph produces a vertical pulse on the bus chassis that is well within the manufacturer's design envelope. A 4-inch hump or a sharp triangular profile traversed at the same speed approaches the threshold for damaging the bus suspension or jolting standing passengers. The Oregon Department of Education's school transportation rules (OAR 581-053-0014) treat suspension and passenger-comfort considerations as part of the bus-route review.

For bus-route streets, two design alternatives are sometimes more appropriate:

• Speed table (22-foot flat-top) -- gentler on buses, lets buses ride at 20 to 25 mph
• Speed cushion -- has wheel-track gaps that allow a bus's wide axle to straddle

See the speed cushions guide for the cushion details.

Where to Place Speed Humps in a School Zone

Five common placement contexts.

1. Drop-off and pickup loops

A hump placed at the entry and the exit of a drop-off loop slows parents to walking speed near the curb. Cojo's recommended layout is a hump 50 to 75 feet inside the entry, before the queueing zone, and another 50 feet before the exit -- two humps per loop, regardless of loop length.

2. School-frontage residential streets

A series of 2 to 3 humps spaced 250 to 350 feet apart on the residential street fronting the school, with the closest hump no more than 100 feet from the school crosswalk. The speed hump spacing reference covers the corridor calculation.

3. Parent pickup lanes (separate from main parking)

In schools with a dedicated pickup lane, a single hump near the front of the queue is enough -- the queue itself slows traffic; the hump enforces the slow speed at the curb.

4. Crossing approaches

A hump placed 100 to 150 feet ahead of a marked school crosswalk reduces approach speed and stopping distance. For a higher-effort treatment, replace the hump with a raised crosswalk -- the crossing itself becomes the calming device.

5. Bus turnarounds

Avoid humps inside a bus turnaround circle. Place the calming device on the approach road instead.

Signage and Pavement Markings for School-Zone Humps

The MUTCD Part 2C treats speed-hump warnings as standard advisory signage. School-zone overlay signage adds:

• W17-1 (HUMP) advance warning sign -- placed 100 to 200 feet ahead of each hump
• Yellow-and-black chevron pattern painted on the hump face -- 6-inch stripes
• HUMP advance pavement marking -- 50 to 100 feet upstream of the hump
• W17-1P advisory speed plaque (optional) -- "20 MPH"
• Reflective markers -- at hump edges for night visibility
• School-zone advance signage (S1-1 and S5-1) -- separately, per the school-zone authorization

School-Board Approval Process

Most Oregon school districts have a written process. Typical steps:

1. Initiating party -- principal, PTO, or transportation director identifies a calming need
2. Site walk and proposal -- contractor (or district facilities team) prepares a hump-placement plan
3. Transportation review -- district transportation director signs off on bus-route compatibility
4. Risk-management review -- district risk officer reviews liability implications
5. City coordination (if street is public) -- district works with city traffic engineer on advisory signage
6. Board action -- school board approves the project as part of the capital plan
7. Notification -- parents and bus drivers notified before install

Cojo's typical project timeline from initial school request to installed hump is 2 to 6 months for a private school-property install, 6 to 12 months when a public street is involved.

Cojo's Salem-Keizer SD Install

In August 2025 Cojo installed a 12-foot parabolic asphalt speed hump in the parent drop-off loop at an elementary school in West Salem, part of the Salem-Keizer Public Schools district. The principal had logged 40+ near-miss reports over the prior school year. Pre-install spot speeds in the drop-off loop averaged 14 mph; 30 days after install they averaged 6 mph, with no bus-route impact (buses use a separate loop). The school's facilities director extended the design to two adjacent elementary schools in spring 2026.

Plan a School-Zone Hump Project

If you are a school principal, district facilities lead, or a parent group working with a district on calming, Cojo can provide a free site review, a hump-placement plan, and an installation quote. See the speed humps guide for the design context, the speed hump installation in Eugene page for a local case study, or asphalt maintenance services for full scope and pricing.

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