KIGALI - In an attempt to improve roads safety, Rwanda National Police has introduced speed guns that can detect the speed of a vehicle from a distance and also take photographic evidence.

The new devices have already been used and their introduction will restrict drivers from driving at high speed.

Driving vehicles beyond the permissible limit has been a common practice in the city to which police attributed the biggest number of highway accidents.

According to acting Commissioner General of Police, Mary Gahonzire, at least 10 of these gadgets have been purchased and are being used around main roads in Kigali City.

"We are boosting our efforts and so far, we have deployed the speed guns on major highways that have for long been characterized by accidents as a result of over speeding,” Gahonzire said.

She added that police are not trying to be harsh on the public but safeguarding the people’s lives.

According to the police boss, the guns have a wide vision and can automatically detect violators at a distance.
There is very little human interference.

The speed guns being used now by the traffic police can detect a vehicle’s speed only when these are pointed towards it.

In the new system, the data about the vehicles can be transmitted to a computer within seconds.

However, Gahonzire said that they have not moved to that level of levying fines to speed violators.

"At the moment we are carrying out sensitization of safety driving among drivers, handing them brochures,” she said.

The current traffic instructions indicates that driving within the city should not exceed 40km per hour while on highways outside the city is 60km/hr.

Most speed guns calculate the speed of a car by sending out a beam of infrared light.

Ideally, this should be targeted at the number plate of a car, because they have a special reflective coating which bounces the beam straight back to the machine.

As the car moves, the device quickly takes a series of distance readings to work out the speed of the vehicle.

Some devices take as many as 20 readings in a few seconds to calculate the speed, and the speed gun moves a lot faster than sound, roughly 30 cm per nanosecond.

The gun counts the number of nanoseconds it takes for the round trip, and by dividing by two it can calculate the distance to the car.

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