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Evaluation of in-car speed limiters – Field study

Varhelyi, Andras LU and Mäkinen, Tapani (1998) Working Paper R 3.2.2.
Abstract
MASTER (MAnaging Speeds of Traffic on European Roads) aims to provide recommendations for speed management strategies and policies and to elaborate guidelines for the development of innovative speed management tools. Within the framework of the project, field trials with a car equipped with a speed limiter were carried out in three “regional typical” European countries: Sweden, the Netherlands, and Spain.



Measurements were conducted in real traffic using an unobtrusive instrumented vehicle, with all the instruments hidden and the subjects driving alone. The subjects, 20-24 per country drove twice, once with the “limiter off” and once with the “limiter on” along a test route. The length of the test routes was 20 - 30 km... (More)
MASTER (MAnaging Speeds of Traffic on European Roads) aims to provide recommendations for speed management strategies and policies and to elaborate guidelines for the development of innovative speed management tools. Within the framework of the project, field trials with a car equipped with a speed limiter were carried out in three “regional typical” European countries: Sweden, the Netherlands, and Spain.



Measurements were conducted in real traffic using an unobtrusive instrumented vehicle, with all the instruments hidden and the subjects driving alone. The subjects, 20-24 per country drove twice, once with the “limiter off” and once with the “limiter on” along a test route. The length of the test routes was 20 - 30 km consisting of urban street network, rural roads and a motorway stretch. Different speed limits typical for urban (30 or 50, 60 km/h) and inter-urban roads (70 - 120 km/h) were included. The speed limiter was continuously set on the speed limit. The dependent variables were speed, car-following behaviour, giving-way behaviour to other road-users, driver workload, and driver opinions.



The speed limiter reduced speeds significantly on roads with speed limits from 30 to 70 km/h. On the other hand, no significant changes could be shown on 80 - 90 km/h roads and motorways. The analysis of so called free speeds, i.e. those travelling outside platoons indicated that heavy traffic slowed down the speed level of traffic flow below the prevailing speed limit on these stretches minimising the role of the speed limiter.



The indicators of positive effects by the speed limiter were as follows:

- large speed reductions in free driving conditions (smaller effects in heavy traffic),

- decreased speed variance,

- approach speeds at roundabouts, intersections and curves became smoother,

- increased time-gaps in the speed interval 30 - 50 km/h, indicating a safer following behaviour

- increased acceptance after having driven with the limiter.



No significant effects were found on:

- turning speeds,

- giving way behaviour towards pedestrians, cyclists and other cars,

- experienced subjective safety when driving with a car equipped with a speed limiter.



The indicators of negative effects by the speed limiter were as follows:

- decreased time-gaps in car-following situations on rural roads, especially in the speed interval between 70 and 90 km/h which indicates a less safe following behaviour,

- increased travel time,

- increased frustration and stress, less patience.



The main conclusion is that automatic speed limiting by an in-car equipment is promising within built-up areas. The acceptance of the system amongst drivers is the highest there. On the other hand, data from rural conditions was scant and there was not much free driving on rural roads involved in the study.



Further research should be directed towards: the long-term effects of speed limiters installed in a larger amount of vehicles (a large scale demonstration trial) within a built-up area with a wide range of participants identically designed in a number of regional typical European countries. Also more data on rural driving is needed for further conclusions. (Less)
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organization
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published
subject
volume
Working Paper R 3.2.2
pages
116 pages
publisher
MASTER Consortium
language
English
LU publication?
yes
id
b025749c-6c1b-4864-913f-cc7346f915d9 (old id 4469013)
date added to LUP
2014-06-23 13:42:33
date last changed
2016-04-16 07:19:39
@misc{b025749c-6c1b-4864-913f-cc7346f915d9,
  abstract     = {MASTER (MAnaging Speeds of Traffic on European Roads) aims to provide recommendations for speed management strategies and policies and to elaborate guidelines for the development of innovative speed management tools. Within the framework of the project, field trials with a car equipped with a speed limiter were carried out in three “regional typical” European countries: Sweden, the Netherlands, and Spain. <br/><br>
<br/><br>
Measurements were conducted in real traffic using an unobtrusive instrumented vehicle, with all the instruments hidden and the subjects driving alone. The subjects, 20-24 per country drove twice, once with the “limiter off” and once with the “limiter on” along a test route. The length of the test routes was 20 - 30 km consisting of urban street network, rural roads and a motorway stretch. Different speed limits typical for urban (30 or 50, 60 km/h) and inter-urban roads (70 - 120 km/h) were included. The speed limiter was continuously set on the speed limit. The dependent variables were speed, car-following behaviour, giving-way behaviour to other road-users, driver workload, and driver opinions. <br/><br>
<br/><br>
The speed limiter reduced speeds significantly on roads with speed limits from 30 to 70 km/h. On the other hand, no significant changes could be shown on 80 - 90 km/h roads and motorways. The analysis of so called free speeds, i.e. those travelling outside platoons indicated that heavy traffic slowed down the speed level of traffic flow below the prevailing speed limit on these stretches minimising the role of the speed limiter.<br/><br>
<br/><br>
The indicators of positive effects by the speed limiter were as follows:<br/><br>
-	large speed reductions in free driving conditions (smaller effects in heavy traffic),<br/><br>
-	decreased speed variance,<br/><br>
-	approach speeds at roundabouts, intersections and curves became smoother,<br/><br>
-	increased time-gaps in the speed interval 30 - 50 km/h, indicating a safer following behaviour<br/><br>
-	increased acceptance after having driven with the limiter.<br/><br>
<br/><br>
No significant effects were found on:<br/><br>
-	turning speeds,<br/><br>
-	giving way behaviour towards pedestrians, cyclists and other cars,<br/><br>
-	experienced subjective safety when driving with a car equipped with a speed limiter.<br/><br>
<br/><br>
The indicators of negative effects by the speed limiter were as follows:<br/><br>
-	decreased time-gaps in car-following situations on rural roads, especially in the speed interval between 70 and 90 km/h which indicates a less safe following behaviour, <br/><br>
-	increased travel time,<br/><br>
-	increased frustration and stress, less patience.<br/><br>
<br/><br>
The main conclusion is that automatic speed limiting by an in-car equipment is promising within built-up areas. The acceptance of the system amongst drivers is the highest there. On the other hand, data from rural conditions was scant and there was not much free driving on rural roads involved in the study.<br/><br>
<br/><br>
Further research should be directed towards: the long-term effects of speed limiters installed in a larger amount of vehicles (a large scale demonstration trial) within a built-up area with a wide range of participants identically designed in a number of regional typical European countries. Also more data on rural driving is needed for further conclusions.},
  author       = {Varhelyi, Andras and Mäkinen, Tapani},
  language     = {eng},
  pages        = {116},
  publisher    = {ARRAY(0xcd81760)},
  title        = {Evaluation of in-car speed limiters – Field study},
  volume       = {Working Paper R 3.2.2},
  year         = {1998},
}