Understanding direct and indirect driver vision in heavy goods vehicles - Summary Report
The research described in this report has been performed by Loughborough Design School (LDS) under the CLOCS programme funded by TfL. The project was specified to allow an understanding of the variability of blind spots in direct vision through windows and indirect vision through mirrors for the top selling HGVs in the UK. The impetus for the research was the increasing number of accidents between Vulnerable Road Users (VRUs) and HGVs in London. The aim was to compare the manufacturers’ most sold vehicle specifications to determine which vehicle design variables can affect the size of blind spots, and to explore issues that have been raised in previous research including the potential for construction HGVs to be involved in more accidents with VRUs than distribution variants of HGV designs. The LDS team have utilised a virtual modelling technique to explore this issue. This virtual approach allows multiple accident scenarios to be modelled and simulated. In order to allow the analysis of vehicle blind spots 19 vehicle models have been created by digitally scanning the real world vehicles. The vehicles that have been modelled include construction, distribution and long haul HGV designs, as well as ‘high vision’ low entry cab designs. These models have been used in combination with simulations of cyclist and pedestrian VRUs in a manner which recreates critical accident scenarios that have been defined through the analysis of accident data. This involves placing the simulated VRUs in a number of defined locations adjacent to the vehicle. Subsequently the simulated VRUs are moved away from the vehicle into a position where they ‘just can’t be seen’ by the driver of the vehicle, i.e. if they were moved further away they would be partially visible to the driver. The distance that the VRU simulation is away from the side or front of the vehicle cab determines the size of the direct vision blind spot. In this way vehicle designs and configurations can be compared. In addition to this further testing was performed to determine if the VRUs located in the direct vision blind spots could be viewed by the driver through the use of mirrors. The final analysis technique utilised a method which projects the volume of space that can be seen by a driver through the windows and mirrors on the surface of sphere. This provides a field of view value which can be used to compare the glazed area of HGVs and provides a method to distinguish between vehicles that perform at the same level in the VRU simulation. The results of the work highlight the follow key issues. 1. All standard vehicle configurations have blind spots which can hide VRUs from the driver’s direct vision 2. The height of the cab above the ground is the key vehicle factor which affects the size of direct vision and indirect vision blind spots 3. The design of window apertures and the driver location in relation to these window apertures can reduce the size of the identified blind spots. i.e. two different vehicle designs with the same cab height can have different results for blind spot size due to window design and driver seat location 4. Low entry cab designs, which are the lowest of the 19 vehicles tested, demonstrated real benefits in terms of reducing direct vision blind spots when compared to standard vehicle designs 5. The construction vehicles assessed in the project are on average 32% higher than the same cab design in the distribution configuration 6. For construction vehicles the distance away that a pedestrian in front of the vehicle can be hidden from the driver’s view is on average nearly three times greater than the distribution vehicles 7. For the construction vehicles the distance away that a cyclist to the passenger side of the vehicle can be hidden is on average more than two times greater than the distribution vehicles 8. The work has highlighted the need for a new standard which defines what should be visible through direct vision from the vehicle. Such a standard does not currently exist, and is seen as a key mechanism for improving future vehicle designs.
This paper was sponsored by Transport for London