| 摘要 |
A retractable speed bump helps control the speed of a vehicle traveling through a special speed zone such as a school zone or a road construction site. A housing is either buried in the roadway or is placed into a ramp that seats on top of the roadway, the housing having a retractable canister therein, which canister extends above the housing in response to the speed of a vehicle as detected by a speed sensor. The greater the speed of the vehicle, the greater the level of extension of the canister. The canister may have tire shredding spikes or explosive charges therein.
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