Självförklarande gator: samband mellan faktisk hastighet, hastighetsgräns och trafikmiljö


The aim of this study was to improve the understanding of the concept of self-explaining roads in urban areas by studying the relationship between speeds at a particular location, the speed limit and the road environment. The relationship between actual speed levels, speed limit and traffic environment has been studied based on earlier speed measurements in 23 different cities and a total of 69 measuring points. In addition, traffic engineers from 73 different municipalities studied photos from 20 different locations and made an assessment of the speed limit at the site, so-called blind estimation.

The results show that when the relationship between the speed levels and a number of site-specific background variables was studied, the actual speed levels were explained not only by road-specific variables such as speed limits, traffic flow and road type, but also variables that describe the surrounding environment such as type of area (inner city, residential areas, outside city areas) and presence of vulnerable road users. Blind-estimates of speed limits show that it is difficult to estimate a speed limit only by looking at a photo. Roads with speed limit 70 km/h were most easy to estimate (67% hit-rate) and roads with speed limit 60 km/h were most difficult (35% hit-rate). A logistic regression showed that lane width was the most important factor when predicting the speed limit by only looking at a photo.

The results showed that the probability of a correct estimate of the speed limit increases the narrower the road gets. In conclusion, the concept of self-explaining roads in urban areas is very difficult with the existing speed limits it is not a reality today from a national perspective. It is far from easy for the road users to assess the present speed limit by only looking at the road and traffic environment if they for some reason failed to notice the speed limit sign.



Millions for research into maritime transport and the environment

Maritime transport is a major source of emissions of harmful air pollutants and carbon dioxide. In a new project, a research team from the Swedish National Road and Transport Research Institute (VTI) and the University of Gothenburg has received SEK 6.4...


New research programme for more efficient travel

The Swedish National Road and Transport Research Institute (VTI) is playing an important role in a major new research programme to find radical solutions leading to fewer trips and more efficient travel, along with tools to enable better use of roads and...


Simulator used to practice emergency responses safely

Emergency responses of the police, ambulance, and rescue services are associated with a high risk of accidents, but practicing them in real traffic is neither safe nor permissible. A simulator-based method developed by the Swedish National Road and Transport...


Simulation of cut-in by manually driven vehicles in platooning scenarios

A study in a VTI-driving simulator has showed that a platoon will be able to handle a cut in from a manually driven car. The results of this study have recently been presented at two conferences in Japan.



The five-year anniversary of European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017.


Self-driving buses in Sweden next year?

A self-driving, fossil-free bus. This idea might become reality through a forthcoming collaborative project involving the Swedish National Road and Transport Research Institute (VTI), Linköping University and several other participants. The project group aim...