Arrive Alive

Stopping Sight and Driver Reaction Time

Stopping Sight Distance

S=dr+db

S=stopping sight distance
dr=driver reaction distance (decision distance - combined observation, identification and decision distance)
db=braking distance (action distance)

dr=v.tr

db=(v*v)/(2g(f+-G))

v=speed
tr=driver reaction time (varies from 2,5 to 2,8sec)
g=acceleration of gravity
f=coefficient of friction between tyres and pavement (varies with speed – for wet, glazed asphalt it varies from about 0,45 at a speed of 10km/h to 0,2 at a speed of about 70km/h)
G=average grade

The above distances depend on whether a vehicle goes into a skid or not – distances increase drastically when vehicles go into a skid.


 

 

The type of vehicle (vehicle mass – together with speed relating to momentum) also plays a role – for example : in emergency situations a light passenger car doing in the order of 100km/h needs about 60m to stop, a truck weighing less than 5t would require about 70m and a truck weighing between 5t and 10t would require in the order of 80-90m (both doing about 100km/h). (In all these cases vehicles do not go into a skid situation and distances given do not include driver observation and decision distances).

Speed plays a major role in driver observation, recognition, decision and reaction time. In the case of a hazard or an incident on the road, the driver of a medium size motorcar driving at a speed of 120 km/h will need a total distance of about 227 metres from the point of observing a hazard and taking evasive action until the vehicle comes to a standstill. For a driver driving at a speed of 180 km/h this distance more than doubles to about 480 metres. Information on the total observation, recognition, decision and reaction distances required for various sized motorcars and speeds on a flat section of road are given in the graph below.

 

 

Required Stopping Distance - metres
Decision distance plus Action distance
Speed
km/h
Small
Car
Medium
Car
Large
Car
Heavy
Vehicle
60 60 66 77 116
70 78 86 101 154
80 99 109 129 197
90 121 135 159 246
100 146 163 193 300
110 174 193 230 359
120 203 227 271 424
130 235 263 314 495
140 269 301 361 570

 

 

Required Stopping Time - metres
Decision Time plus Action Time
Speed
km/h
Small
Car
Medium
Car
Large
Car
Heavy
Vehicle
60 5.73 6.44 7.76 12.37
70 6.50 7.32 8.87 14.24
80 7.27 8.21 9.97 16.11
90 8.03 9.09 11.07 17.98
100 8.80 9.97 12.18 19.86
110 9.56 10.86 13.28 21.73
120 10.33 11.74 14.38 23.60
130 11.09 12.62 15.49 25.47
140 11.86 13.51 16.59 27.34

 

Also View:

Brakes/Braking and Road Safety

 

Loading...

Search Road Safety Articles

Latest Pages

RAF Buddy and Road Safety

RAF Buddy and Road Safety

In a groundbreaking move to address the rising concerns of road safety in South Africa, RAF Buddy, Accisure, and Arrive Alive have joined hands in a strategic partnership. This collaboration aims to promote awareness, education, and proactive measures to reduce road accidents and enhance overall safety

Read More

Traffic Colleges / Academies as approved by the Minister

Traffic Colleges / Academies as approved by the Minister

Address Head of the College Contact Details Name of Training Institution Provincial Colleges Postal Address: Private Bag X4000 Mutale 0956 Physical Address: Thengwe Road (Next to Mutale Driving

Read More

MVA Fund Partners with the Arrive Alive Online Initiative

MVA Fund Partners with the Arrive Alive Online Initiative

The MVA Fund and the Arrive Alive Online Initiative are thrilled to announce their partnership dedicated to safer South African roads and empowered recovery for accident victims. MVA Fund Providing essential financial relief to those impacted by motor vehicle accidents, ensuring you continue to

Read More

Eye Protection and Road Safety

Eye Protection and Road Safety

Our eyes and eyesight are perhaps the most important of our senses on the road. Seeing is a highly active function. Our eyes continually move and adjust, receiving a constant flow of visual impressions. Normally, all this activity happens routinely and without noticeable strain. It is important to

Read More

Windscreen Diagnostics

Windscreen Diagnostics

On the Arrive Alive website, we find a detailed discussion on the importance of the windscreen for road safety. We emphasize the importance of visibility through the windscreen for the roadworthiness of the vehicle as well as the importance of the windscreen for the structural integrity of the car. It

Read More

Chip Repair and Windscreen Safety

Chip Repair and Windscreen Safety

Introduction Have you been driving with a small chip on your windscreen, fearful that it may expand into a running crack along with the windscreen? We decided to approach some of the experts for more information as to how and when such a chip can be repaired and when a windscreen would need to

Read More

Load More Pages

Partners

View All