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Visibility - braking distance

Braking distance

The calculation of braking distance:

s: total braking distance [m] (s=sR+sF)
sR: perception reaction distance [m]
sF: braking deceleration distance [m]

Perception reaction distance:

sR=(v/3.6)tR/3.6

v: speed of vehicle [km/h]
tR: reaction time [s]

To reduce the kinetic energy to zero:

µmgsF=m(v/3.6)2/2

µ: coefficient of friction [ ] (between the tires and the road)
m: mass of vehicle [kg]
g: acceleration of gravity [9.81 m/s2]

it follows:

sF=(v/3.6)2/2µg=0.004v2

The total braking distance:

s=sR+sF

A. reaction
B. perception
C. decision
D. action

Braking distance

 

Braking distance - calculated values

Possible values:

µ: coefficient of friction [ ]:

new tire, dry road: 0.85-0.7
new tire, wet road: 0.65-0.2
worn tire, dry road: 1.0-0.9
worn tire, wet road: 0.5-0.1
snow, ice: 0.1 and less

reaction time [s]: 0.5-2.5

Calculated values:

conditions of calculation:

horizontal road
µ= 0.5 (medium adhesion between the tire and the roadway)
tR= 1.5 [s] (medium reaction)

Calculated results:

Braking distance - calculated values

 

Visibility - braking distance

visibility/color of clothing: braking distance/speed:

Visibility - braking distance

 

Visibility at night

Visibility at night

Távolság, melynél a járművezető első ízben látja a gyalogost

1. sötét ruházat (fekete, kék)
2. piros ruházat
3. sárga ruházat
4. fehér ruházat
5. fényvisszaverő viselése

Cornell University Cooperative Extension Program Report "Actionwear: Clothing for Fitness." - alapján.

 


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