Citation

Bergh T, Carlsson A, Larsson M. Int. J. Crashworthiness 2003; 8(2): 159-167.

Copyright

(Copyright © 2003, Informa - Taylor and Francis Group)

DOI

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PMID

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Abstract

The objective of this paper is to present the Swedish Vision Zero Experience concerning separating car traffic with cable barriers and upgrading traffic safety on existing 13 m roads using low cost measures. There is a significant difference in traffic performance, safety, investment and maintenance costs, land requirement and intrusion between normal two-lane and four-lane cross-sections. In Sweden, this gap has been narrowed with a 13 m road with 3.75 m traffic lanes and 2.75 m hard shoulders. The traffic performance of these roads is quite satisfactory but there are safety problems with fatal accidents. The main problem on all two-lane roads is run-off road and head-on accidents causing more than 66% of all fatalities. The event process tends to be the same. The driver loses control for some reason and crashes against some obstacle in the roadside area or opposing vehicle. In 1998, the Director General of SNRA decided on a full-scale programme to improve traffic safety on six existing 13 m roads using low-cost measures, preferably within the existing right-of-way. The main alternative is the 2+1 solution with a separating cable barrier, preferably within the existing 13 m width. This solution was estimated to have a potential to prevent some 50% of all severe link accidents. Findings so far have been so successful that SNRA has decided to generally replace the old 13 m roads with the 2+1 solution. The main results and findings up to May 2001 are as follows: Level-of-service for normal traffic is better than expected. Speed performance on 2+1 roads with cable barrier is the same, or even better than an ordinary semi-motorway at one directional flows up to 1400 v/h. The capacity is estimated to be about 1 650 v/h in one direction, some 300 v/h less than for an ordinary 13 m road. Emergency and tow agencies are complaining as their workload have increased. The transition zones from 2 to I lane have performed well. The proportion of vehicles in the beginning of the zone is small. Drivers tend handle the design of the transition zones in a cautious and responsible manner. The traffic safety effect on severe accidents was expected to be high on 2+1 road with cable barrier. So far in eight objects total length there has not been any fatal and only 6 persons with severe injuries. This is about 60% less than on ordinary semi-motorways and supports the prediction that fatal and severe injuries can be reduced with up to 50%. Median cable barrier crashes are very frequent but normally without person injuries. They are often caused by skidding, flat tire or loss of control. A number of possible severe accidents have been converted by means of the median cable barrier to crashes with slight or no injuries. Driver attitude surveys show that drivers attitude to roads with cable barrier have been changed in a positive direction. About 40% of the drivers say it is the best design. General survey shows that about 76% say that they want all major roads to have median barrier. The maintenance costs are increased with about 120 Thousand SEK (12000 USD) per km per year. The main costs are cable repairs with 80 Thousand SEK (8000 USD) per km per year. Work zone safety at cable barrier repairs is a major concern. give an overview of the SNRA development program to upgrade traffic safety on existing 13 in two lane roads with 2 + 1 conversion with median cable barrier as the main tool present an overview of all important results and empirical findings until April 2001 from opened projects as yet, totally some 365 kin (2001).

Language: en