Effects of visibilities on road traffic accidents at priority junctions in low speed areas: Analysis of 120 locations in Portsmouth, UK

Research output: Contribution to conferenceAbstractpeer-review


In 2007 the Manual for Streets (MfS) was published which set out new approaches to the design of priority junctions in built up areas. This new approach promoted lower visibilities for drivers on minor road arms, compared to those set out in the Design Manual for Roads and Bridges. Priority junctions are the most common type of junction and the locations of high numbers of road traffic accidents in the UK, especially those involving pedestrians and cyclists. By reducing the visibilities for drivers, MfS aimed to reduce the corresponding speeds of drivers on the minor road approach, thus reducing the level and severity of accidents. In 2007 Portsmouth became the first city in the UK to adopt 20mph speed limits on the majority of residential streets. Existing research into the determinants of road traffic accidents at priority junctions indicates vehicle speeds and visibilities as important variables. Whether these relationships hold true in the context of low speed limit areas has not been explored in the literature. This research evaluates the effect of visibilities at low speed (20mph) junctions through analysis of 120 locations around the city of Portsmouth. Speeds on all approaches were collected alongside classified vehicle counts, detailed measurements of junction geometries and visibilities. This rich dataset was combined with Department for Transport STATS19 data on road traffic accidents at these locations. Multivariate Generalised Linear Regression, Structural Equations Modelling and Artificial Neural Network models were built and compared in order to represent the complex interplay between vehicle speeds, speed limits, visibilities, geometries, flows, and road traffic accidents. Initial findings present new insights into the effects of visibilities on accidents in the context of low speed/low speed limit priority junctions.
Original languageEnglish
Number of pages12
Publication statusPublished - 6 Jul 2022
EventUniversities Transport Group Studies (UTSG) 54th Annual Conference - Edinburgh Napier University, Edinburgh, United Kingdom
Duration: 4 Jul 20226 Jul 2022
Conference number: 54


ConferenceUniversities Transport Group Studies (UTSG) 54th Annual Conference
Abbreviated titleUTSG2022
Country/TerritoryUnited Kingdom
Internet address

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