Impacts of road geometry on driving behaviour

Tiegeometrian vaikutukset ajokayttaytymiseen

Car driver fits his behaviour to the limits set by road geometry. A wide road tempts to drive fast, hills and bends reduce speed and overtaking possibilities. Other road users affect driving behaviour, as well as regulations and legislation. The aim of this study was to find out, based on recent literature, how geometric design (horizontal and vertical design and width) of road can affect speed and other driving behaviour. Our research concentrated on one-carriageway, two-lane rural roads outside junction areas. Possibilities to affect road users were studied in different types of roads, surroundings, and other circumstances. If consecutive curves differ a lot from each other, it leads to more intense decelerations when approaching the curves. Small radii lead to harsh accelerations and decelerations. Many drivers underestimate their driving speed. The lateral position of cars varies a lot when the radius of a curve is less than 200 m. Trying to compensate poor geometry only by widening a road or by giving more optical guidance (like side poles) does not seem to improve road safety, based on Finnish experience. Missing overtaking possibilities led not only to poor traffic fluency but also to risk taking driving behaviour. Widening a road tends to increase both speeds and number of overtakings, but this does not increase accident risk if alignment and profile are of the same quality as the width. Wide shoulder is good for pedestrian and bicycle safety, and also for car safety especially at curves. Wide lane increases the number of overtakings, but a bigger proportion of them can be performed without disturbing oncoming cars. The impact of geometric design on driving behaviour has not been studied intensively over the last 10 years. Much more emphasis has been put on telematics both in Europe and in the USA. The gaps revealed in this study concern weather and lighting, combined influence of different design elements, taking into account different vehicle classes or road user groups, and understanding the impacts of lateral position of vehicles. Cruise control and other similar equipment are common nowadays, but their impact on driving behaviour, and further on road safety, is not deeply studied. Factors affecting overtaking behaviour, or differences in overtaking manners between different regions could be better understood. Measuring and analyzing visual and cognitive load of driver needs still more research also from the point of view of geometric design of road. This report may be found at http://alk.tiehallinto.fi/julkaisut/pdf2/3201132-v_tiegeometr_vaik_ajokaytt.pdf

• Record URL:
  http://alk.tiehallinto.fi/julkaisut/pdf2/3201132-v_tiegeometr_vaik_ajokaytt.pdf
• 
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9789522212092
• Authors:
  • PASANEN, J
  • RASANEN, J
  • GRANLUND, R
  • VEHMAS, A
• Publication Date: 2009

Language

• Finnish

Media Info

• Pagination: 76p+app
• Serial:
  • TIEHALLINNON SELVITYKSIA, FINNRA REPORTS
  • Volume: 3201132
  • Issue Number: 18/2009
  • Publisher: Finnish Road Administration
  • ISSN: 1457-9871

Subject/Index Terms

• TRT Terms: Alignment; Behavior; Cross sections; Layout; Speed; Surface course (Pavements); Traffic flow
• Uncontrolled Terms: Longitudinal profile
• Geographic Terms: Finland
• ITRD Terms: 2894: Alignment; 9001: Behaviour; 6404: Cross section; 8035: Finland; 2885: Geometric design; 2825: Profile (longitudinal); 5408: Speed; 671: Traffic flow
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors; I21: Planning of Transport Infrastructure;

Filing Info

• Accession Number: 01321564
• Record Type: Publication
• Source Agency: TRL
• ISBN: 978-952-221-209-2
• Files: ITRD
• Created Date: Nov 29 2010 11:39AM