do speed bumps work, measure traffic speed parking lot, speed bump effectiveness, before and after speed study

Guide \u00b7 Results

How to tell if your speed bumps worked

Content reviewed 2026-11-09

Short answer

Measure before you install, not only after. Record speeds at the same spots, times and days, count complaints and near misses, then repeat a few weeks after installation. If typical speeds and the number of very fast drivers dropped, the devices worked; if speeds come back between bumps, the fix is usually spacing, not more height.

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What to measure

Keep it simple enough that the same person can repeat it.

Measure	How	What good looks like
Typical speed	Time 20+ cars over a marked distance	Clear drop at and between devices
Very fast drivers	Count cars well over your posted limit	Fewer of them
Complaints	Log from residents, tenants or staff	Fewer speed complaints, few new noise ones
Near misses / incidents	Security or staff reports	Fewer reported events

A simple timing method

Mark two points a known distance apart, for example 100 ft. Time each car between them. Speed in mph is about 68 divided by the seconds for a 100 ft run (100 ft ÷ seconds × 0.68). Do it at the busiest and the emptiest times, because speeding is often worst when the lot is empty.

Reading the results

If speeds drop at the bump but climb in the middle of a long run, add a device or tighten spacing. If drivers swerve around the ends, extend the device to the curb or add delineators. Share the numbers: a board or owner approves future work faster when they can see the first project worked.

Buying terms

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Anchor hardware and end caps included; 5-year commercial warranty.
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Frequently asked

How do I measure speed without a radar gun?

Time cars over a measured distance with a stopwatch or phone video, or borrow a speed feedback sign. Use the same method before and after.

How long should I wait to measure after installing?

Give drivers a few weeks to settle into the new layout, then measure at the same times and days as your before count.

What if speeds dropped only near the bump?

That is normal. Speeds rise again with distance, which is why spacing matters. Add a device or adjust spacing on long runs.

What should I report to the board?

Typical speed before and after, number of very fast drivers, complaints and incidents, and what you will adjust next.

Sources & standards

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