The stopping distance

The stopping distance is the distance at which a vehicle traveling at an initial rate to a complete stop. This basic parameter security is dependent on the speed of the driver's reactions, quality brakes and tire grip.

Needed to stop the track consists of two parts - the reaction path and its own braking distance. Response runway is traveled by the driver when detects a critical situation, processes it and begins to brake. It takes about one second, depending on the speed of the driver's reaction. At this time, however, the vehicle continues to move at an unchanged rate. For example. at 50 km / h, the reaction path 14 m long. Only then the brakes are engaged. Stopping distance depends on the initial speed and many other factors.

The speed of the car	The reaction path	The stopping distance	Track stop
dry roads
50 km / h	14 m	14 m	28 m
60 km / h	17 m	20 m	37 m
80 km / h	22 m	35 m	57 m
wet roads
50 km / h	14 m	19 m	33 m
60 km / h	17 m	28 m	45 m
80 km / h	22 m	49 m	71 m
ice
50 km / h	14 m	64 m	78 m
60 km / h	17 m	93 m	110 m
80 km / h	22 m	165 m	187 m

Source: www.ibesip.cz

Braking is about the next course. From sightings of obstacles until the brake on a bicycle elapsed time "t _r". This is a driver's reaction time and the time at which the driver moves the foot on the brake pedal. Another time period denoted "t _p", this is the time delay brakes. At this time, will be identified and overcome in the joints and bearings, brake pads lands on friction brakes. Thus far goes the neglect of the car rolling resistance unabated speed. Another section is called the rise time the brakes, which is the time at which the brake performance reaches its peak, the 't _n'. In the next period of time "t _u", ie during full braking, assuming a constant deceleration to a stop. The course of the size of braking force is shown in the following chart.

Self braking distance, hence the time is full braking and ramp braking is affected by tire adhesion - adhesion.

The dependence of the surface type and length of braking distance:

Surface	The coefficient of increase in braking distance
Dry concrete	A
Dry asphalt	1.3
Dry pavement	1.4
Wet Concrete	1.5
Wet asphalt	1.8
Wet pavement	2.6
Snow	3.3
Ice at -20 ° C	5.6
Ice at -10 ° C	7.6
Ice at 0 ° C	10.3

Safety distance of vehicles
Follow a safe distance in front of a moving vehicle. Safety distance increases with increasing speed and is equal to the minimum distances covered in 2 seconds. 2 seconds is the approximate time it takes for your vehicle starts to brake effectively.

What do you know?

What is the braking distance of a tram and bus stop?
Prague transport company performed a test experiment, in which both tram and bus traveling at 40 km / h should stop. Length of braking distance was 26 m tram, bus managed to stop the 12-meters. For comparison, the Audi TT stops at less than 6 meters.

Video:

Text: John Sajdl
Photo: www.ibesip.cz, www.highwaycode.gov.uk, archive
Keywords: brakes, braking distance, braking distance, reaction time, a safe distance