The influence of variations in sunlight associated with latitude and the annual solar cycle on driving, road traffic accidents and orientation transport infrastructure

A wide range of factors and influences impact on a person’s ability and performance when driving a car or other road vehicle. These can be broadly divided into those relating to social and economic influences intersecting with a driver’s own physical and mental wellbeing and individual characteristics, and secondly into factors concerning the external environment ranging from the condition of the vehicle, the weather conditions, the road layout and the time of day (Ashley, et al., 2015; Donkers, Yang, and Viktorović, 2020). This mix of factors may have a benign impact and not precipitate situations in which the driver’s ability to manage potentially dangerous combinations of circumstances becomes compromised. Previous research has shown that short-term solar glare can impair a person’s driving ability, which can be especially important when emerging from east-west oriented tunnels (Pérez-García, Aranda and Norena, 2023). Other researchers have focused on the periods around sunrise and sunset when the sun is low in the sky (Khumalo and Vander Schuren, 2015). The transition to autonomous vehicles may be expected to reduce the potential for erratic driving by human drivers, nevertheless solar glare may continue to provide passengers with unwelcome and unpleasant visual experiences, especially among the cohort who have previously been accustomed to driving vehicles themselves. More significantly, Nicholas and Chung (2018) have investigated the difficulties associated with direct sunlight impacting on machine vision systems.

The previous research reflects awareness of factors impacting on driving and their potential to contribute to situations in which road traffic accidents (RTAs) occur. However, little consideration has concerned the variations of sunlight and solar glare associated with different latitudes and their potential contribution to driving performance. In temperate latitudes, such as in the UK, there are two main periods in the annual solar cycles when the sun is relatively low in the sky in the autumn and spring. These periods typically coincide with weather conditions that are cloudy and wet or dry and sunny, although cloudy and sunny days also frequently occur potentially producing relatively rapid changes between bright sunlight and dismal overcast conditions. In these circumstances, drivers navigating familiar or unfamiliar roads and junctions can find themselves suddenly staring directly into the sun, which may temporarily affect their driving ability. Earlier research has suggested that 40-60% of RTAs occur at road junctions (Wada, et al., 2023), and the situation seems to worsen with changes in the gradient and non-perpendicular turns at the junctions where drivers are likely to be changing direction and orientation in relation to sunlight.

The overall aim of the research is to explore the impact of annual solar cycle variations in direct sunlight on driving and the occurrence of RTAs. The research will focus on the UK, which spans approximately 10 degrees of latitude, and provides the opportunity for comparison across a range of urban and rural contexts and environmental settings. The doctoral researcher may have the opportunity to guide the research in different directions with a focus on the following research questions:

·        Does the sun’s elevation at different latitudes during the course of its annual cycle have a statistical association with the occurrence of RTAs, weather conditions and time of day?

·        Does the layout of junctions, orientation and gradient of roads in respect of exposure to direct sunlight at different latitudes and times of the year affect driving performance?

·        Are drivers aware of the direct sunlight and solar glare influencing their driving ability, and will their awareness vary with latitude and time of day?

It is expected that the analysis will be carried using appropriate geospatial and environmental modelling software using data available from secondary sources, and these include 3D GIS modelling, hill-shade analysis and visibility analysis along the street networks. However, some primary data collection may be required for ground truthing, especially if the emphasis of the research goes towards drivers’ perceptions of the influence of sunlight on their driving ability at different times of the year.

Students with or expecting to be awarded at least an Upper Second Class Honours degree or equivalent are invited to apply. The project is expected to attract graduates from different disciplines, especially those with a geospatial emphasis and appropriate skills, knowledge and experience related to the project.