Naslov
The impact of speed inconsistency on driving safety

Autori
Vukoje, Biljana ; Cvitanić, Dražen

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Sustainable and safe road design from a human behaviour point of view - Challenges for nterdisciplinary work in road safety, Book of abstracts / - Maribor, 2013, 1-8

Skup
26th ICTCT Workshop on: Sustainable and safe road design from a human behaviour point of view - Challenges for interdisciplinary work in road safety

Mjesto i datum
Maribor, Slovenija, 24.10.2013. - 25.10.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
design speed; operating speed; consistency; GPS; horizontal curve; side friction factor

Sažetak
The geometric features of the road play a significant role in driving safety considering the fact that accidents often occur on horizontal curves. One of the main reasons for accident occurance is the lack of geometric design consistency in terms of maintaining the desired travel speed which results in road alignment does not fit the drivers´ expectations. A consistent road design ensures coordinated succesive elements producing harmonized driver behaviour with no surprising events. Drivers tend to select speeds with respect to their own perception of the road and those values do not match the design speeds. Beside the succesive elements consistency, a good road design must establish the balance of superelevation and side friction values in curves with the actual driving speeds. The most commonly used indicator of the speed distribution in curves is operating speed which represents the speed below which 85% of drivers operate. Although numerous operating speed studies have been conducted, most of them were based on spot speeds with certain assumptions providing incomplete information about the actual speeds. The limitations of the existing models indicate the need for more detailed analysis of actual driver behaviour and the inclusion of real speeds in the design process. The free flow speed analysis is presented in this paper, with speeds recorded on a segment of the state road D1 in Dalmatia region of Croatia using a new GPS based metodology. This metodology allows the continuous speed data collection and gives an accurate picture of drivers´ behaviour. Operating speed prediction model for horizontal curves was determined based on the speed data on 10 km long road segment, with horizontal curve radius and the approach speed as independent variables. The model validation was made with the data from the 1 km long segment of the road. The values of the operating speeds were compared to the road´s design speed and the differences between side friction values (demand, supply and design) were also made. These deviations point to the need for improving the road design guidelines in terms of harmonizing the values of design speed with actual speeds of most drivers in order of safety.

Izvorni jezik
Engleski

Znanstvena područja
Građevinarstvo

POVEZANOST RADA