SAFETY OF MOVA TRAFFIC SIGNAL CONTROL AT HIGH SPEED JUNCTIONS

In the UK it is a requirement that isolated traffic signals on high speed roads (where the 85th percentile speed exceeds 35 mph) are installed with speed detection equipment (Speed Assessment (SA) or Speed Discrimination (SDE)) or MOVA. Speed Assessment and SDE attempt to find a suitable stage change time that avoids drivers having to make a difficult decision of whether to stop or continue in the face of an amber signal, often referred to as the 'dilemma zone'. Although MOVA was not implicitly designed to do this, the strategy inherently reduces red-running through its stage change decisions and in an earlier study it has been found to be at least as safe as SA or SDE. Also importantly MOVA has proven to be significantly better than standard Vehicle Actuation (VA) traffic signal control in terms of efficiency, capacity and delays. Surveys have estimated that MOVA reduces delays by over 13% compared to junctions under VA control together with significant increases in capacity. MOVA requires configuration data, some of which needs to be measured on-site by observers prior to its installation and should be validated once MOVA is running. Configuration data includes measurements of vehicle speeds in free flow conditions and saturation flows. The thrust of this work was to consider whether the quality of the MOVA configuration data has an influence on safety. The accident records of twenty five high-speed sites that had been converted from SA or SDE to MOVA with no other changes were assessed. As in the earlier study, the results again showed no significant difference in personal injury accidents between MOVA and SDE/SA. The quality of the MOVA configuration data was shown to have a bearing on safety. The sites with better configurations had lower accident records than SA/SDE, while sites with poor configurations had higher accident records. Cruise speed data looked to have the greatest affect on safety. The sites considered in this study represent the earlier MOVA installations. Current practice in configuring and setting-up MOVA sites could well be such that there are fewer 'poor' installations now. It is especially noticeable that the industry has adopted the view that cruise speeds need to be realistic. Developments to MOVA are proposed to improve the ease with which the configuration data is specified, including on-line facilities to measure cruise speeds and saturation flows. (A)

• Corporate Authors:

  TRL

  Crowthorne House, Nine Mile Ride
  Wokingham, Berkshire  United Kingdom  RG40 3GA
• Authors:
  • Maxwell, A
  • CRABTREE, M
• Publication Date: 2004

Language

• English

Media Info

• Features: References;
• Pagination: 7 p.

Subject/Index Terms

• TRT Terms: Crash rates; Crimes; Decision making; High speed ground transportation; High speed vehicles; Highway capacity; Intersections; Prevention; Red; Red interval (Traffic signal cycle); Software; Speed; Traffic control; Traffic delays; Traffic signals
• ITRD Terms: 1612: Accident rate; 643: Capacity (road, footway); 2248: Decision process; 9010: Delay; 1163: High speed; 455: Junction; 1516: Offence; 9149: Prevention; 539: Red light; 8645: Software; 654: Traffic control; 565: Traffic signal
• Subject Areas: Highways; Operations and Traffic Management; Railroads; Security and Emergencies;

Filing Info

• Accession Number: 00987080
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Mar 3 2005 12:00AM