Asphalt Speed Bump: Bump vs Hump, Sizes and Tons of Mix

An asphalt speed bump is a raised section of hot mix built across a driveway, parking lot, or private road to make drivers slow down. It's one of the cheapest permanent traffic-calming options because it's built from the same material as the pavement. The key decisions are the shape (a short, sharp bump or a long, gentle hump), where it goes, and whether you need permission to build it.

How many tons calculator → Asphalt parking lot guide →

Speed Bump vs Speed Hump vs Speed Table

Type	Shape	Typical setting	Effect
Speed bump	Short front-to-back, a few inches tall	Parking lots, private drives	Forces very low speeds
Speed hump	Long, gradual rise, often around 12 feet long and roughly 3 to 4 inches tall	Residential streets, private roads	Moderate slowing
Speed table	Longer hump with a flat top, sometimes used as a crosswalk	Streets, campuses	Gentler slowing; better for larger vehicles

Exact dimensions vary by designer, agency, and local standards. Public streets typically follow the local jurisdiction's traffic calming guidelines, and emergency services often have a say.

Do You Need Permission?

• Public streets: you generally can't build one yourself. Requests usually go through the city, county, or state, which may require a traffic study.
• HOA and private roads: check covenants and bylaws. Some communities require board or member approval.
• Commercial lots: the owner decides, but think about liability, signage, and accessibility routes.
• Your own driveway: usually your call, but check any local rules.

Asphalt vs Prefab Rubber or Plastic

Factor	Asphalt	Prefab rubber or plastic
Install	Needs hot mix, tack, and compaction	Bolted or anchored in place
Look	Blends with the pavement	Usually yellow and black
Removal	Must be milled or cut out	Unbolt and move
Snow plows	Can be damaged but repairable	Often removed in winter
Best for	Permanent installations, humps and tables	Temporary or seasonal needs, trials

Tonnage Math

A bump or hump cross-section is often close to a parabola. The area of a parabolic segment is two-thirds of the width times the height. Using about 145 pounds per cubic foot:

Short parking lot bump: 3 feet (36 inches) front to back, 4 inches tall, across a 24-foot drive lane.

1. Cross-section: 2/3 × 36 × 4 = 96 square inches
2. In square feet: 96 ÷ 144 = 0.67 square feet
3. Volume: 0.67 × 24 = about 16 cubic feet
4. Weight: 16 × 145 = 2,320 pounds, or about 1.2 tons

Street-style hump: 12 feet (144 inches) long, 3.5 inches tall, 20 feet wide.

1. Cross-section: 2/3 × 144 × 3.5 = 336 square inches
2. In square feet: 336 ÷ 144 = 2.33 square feet
3. Volume: 2.33 × 20 = about 46.7 cubic feet
4. Weight: 46.7 × 145 = about 6,770 pounds, or about 3.4 tons

Add some for waste. Small quantities like these are often below a plant's minimum or cost extra, so ask about short-load fees. These are planning estimates; get a local quote for material and labor.

How Asphalt Speed Bumps Are Built

1. Mark the location and shape with paint, perpendicular to traffic.
2. Clean the pavement thoroughly.
3. Apply tack coat so the new mix bonds. See tack coat.
4. Place hot mix and shape it with rakes, lutes, templates, or a mold. Some crews saw-cut a keyway at the edges so the ends don't feather thin.
5. Compact with a plate compactor or small roller while the mix is hot.
6. After it cools, add paint, markings, and warning signs.

Leave a small gap or channel at the gutter line if water needs to drain along the edge. Otherwise the bump can act like a dam.

Placement Tips

• Keep bumps away from sharp curves, intersections, and places drivers can't see them in time.
• Consider accessible routes and pedestrians; avoid blocking crosswalk paths with a sharp bump.
• Space multiple humps so drivers don't speed up between them.
• Make sure delivery trucks, fire apparatus, and plows can pass.

Maintenance

Asphalt bumps take a beating from snowplows, and the edges are where they usually break first. Repaint markings when they fade, seal any cracks at the joint between the bump and the pavement, and patch chipped edges before water gets under them. If a bump is sealcoated with the rest of the lot, touch up the paint afterward so it stays visible. Marking its location with reflective stakes before winter helps plow drivers lift their blades in time.

Bottom Line on Asphalt Speed Bumps

Asphalt speed bumps and humps are an inexpensive, permanent way to slow traffic on private property. Pick the right shape for the speed you want, get any needed approvals, bond the mix with tack coat, and mark it clearly. A typical parking lot bump takes only about a ton of mix, so the setup and labor usually cost more than the asphalt.