Bedömd vägojämnhet på vägar med låga IRI-värden

Sven Dahlstedt

The reported investigation is one part of a project concerning methods for measurement of the longitudinal roughness of roads and the necessary accuracy. In this study the main focus was on the subjective experience of roughness on roads with low IRI-values, i.e. fairly good roads. Using the available roughness data it was also studied how much a random error, added to the IRI-values, would influence the calculated correlations with the subjective estimates. The investigation was carried out as a magnitude estimation experiment, in which some 20 observers made their estimates while travelling as passengers first in a car, and later in a lorry.

The main results of the study were as follows:

- Subjective roughness seems to be a linear function of roughness according to IRI within the studied roughness range.

- The reliability of the observers, and the agreement between them, seems better in the car than in the lorry.

- For the very smooth sections (IRI almost =0) the roughness experienced in the lorry might have been caused by other vibration sources than the road surface.

- For some road sections with a "non-typical" spectral composition of the road roughness it was found that the correlation between IRI and subjective roughness decreased considerably.

- Some observers had even stronger correlations between their subjective ratings and road profile expressed in RMS units than between their estimates and IRI roughness.

- The simulations of random errors added to the IRI-values showed that, within the studied range and with the fairly large number of observations (45), random measurement errors up to at least ± 0,2 IRI-units can be considered insignificant.



ERPUG 2017

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. 



Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes it is important to understand driver related contributing factors, which have been suggested to be the critical reason in 94 per cent of crashes. The overall aim of the project Vehicle Driver Monitoring has been to advance the...


Tomas Svensson new director-general

Tomas Svensson was today appointed Director-General of VTI. Tomas has been acting Director-General since January 2017. 


Crash testing bicycles at VTI

For the first time single bicycle crashes have been simulated at the VTI crash safety laboratory.


A case study exploring firefighters’ and municipal officials’ preparedness for electrical vehicles

A VTI-study presents a social perspective on new vehicle technology. It explores the self-reported preparedness of the fire departments (i.e., rescue services) in Sweden’s three largest cities regarding rescue operations involving electrical vehicles (EVs).


Pioneering research on and about bicycles at VTI

Under what circumstances might cyclists lose tyre grip? What actions could then be taken to prevent a crash? VTI is currently developing a theoretical model of the behaviour of bicycle tyres during braking and steering in different situations and on different...


Virtual pedestrians create efficient stations

If more people are to choose sustainable travel, then the public transport stations of the future must be designed so that pedestrians can get where they are going quickly, without congestion or queues. The Swedish Road and Transport Research Institute (VTI)...