Analysis of driving conditions on low-volume roads in Lithuania assessing geometry parameters of roads

Abstract

The first Lithuanian regulatory document on road design was issued only in 1996. Until now, two more documents have been issued. During the last 20 years both the principles of road design and road classification has changed. The currently valid Road Technical Regulations is the first to divide roads according to their function, however, there is no clear relation between road category and road function. One of the main conditions for sustainable safe traffic is that road must serve its function and be recognizable according to its parameters. Since 1998 the amount of gravel roads has decreased by 13.4 %. However, it was discovered that after reconstruction 4.7% of road sections became potentially dangerous. During reconstruction the road pavement is strengthened, the gravel surfacing is replaced by asphalt pavement. Thus, the speed limit increases, but based on design rules the design speed remains unchanged. Investigation of horizontal alignment of 30 regional roads was carried out in order to assess compatibility of the horizontal alignment elements and their correspondence to traffic safety, to study the sight distance in vertical alignment. It was determined that compatibility of the horizontal alignment elements is sufficient, and the calculated flow speed v85 is 10–20 km/h higher than design speed vp. Analysis showed that the stopping sight distance meets the requirements in all the elements of vertical alignment, whereas, the passing sight distance meets the requirements only in 7% of all elements where the design speed vp = 70 km/h.