Does Modern Urban Road Layout Improve Road Safety: Which Assessment?
M Millot, CETE Méditerranée, FR; B Hiron, CERTU, FR
This paper examines the benefits to road safety of measures to reduce car use
Urban transport policies aim to reduce the car use in town, in favour of public transport, cycling and walking. It involves a new share of public space and new road layout : creation of a tramway or a corridor lane for bus, reduction of the width of arterial road in order to reduce speed and to improve walking and cycling, creation of cycle lane, etc. The first aim of these improvements is seldom road safety. But they may have an influence on road safety, as vulnerable road users are concerned. Moreover they involve new practices of public space which may also have an influence on road safety. All of this has never been studied in the literature. And these tools are more and more implanted in town, without really knowing their effect on road safety. So it was necessary to evaluate these urban road improvements
The study is based on the analysis of seven types of improvements in several French towns : a tramway lane in Nantes, a bus lane in Rouen, a bus lane shared with cycle in Lyon, a reduction of the width of arterial road with creation of cycle lane in Lille, Martigues and Bordeaux, the share of pavement between pedestrian and bicycle and the implementation of separated road lane in Toulouse.
In literature evaluations are often based on quantitative approach, in particular for road safety. But the improvements studied may involve new practices and new uses which may modify road accident types. That?s why the methodology was based on several approaches : a detailed analysis of accident reports to identify accident scenarios before and after the improvement, a detailed analysis of the road layout, several interviews of road designers, users of the road improvement, technical services of the town, shopkeepers, etc. The use of these crossed approaches enables us to better understand how the road layout functions and its influence on road safety.
At first, the results show the necessity to keep data of urban project and the history of road management. It is indispensable to evaluate the tools used.
Then the analysis of several road improvements show the effect on road safety linked to the uses of the road management. For example analysis of cycle lanes often deals with accidents of bicycles. And for this type of users, road safety is assured. But this improvement is often used by motorised two-wheelers in traffic jam and this involves typical accidents. For example drivers don?t appreciate the difference of speed between bicycle and motorised two-wheelers and may cross the trajectory of the motorised two-wheeler.
So this research reveals the necessity to evaluate road layout improvements, in particular when they are systematically applied in favour of a transport policy. It gives some elements of method to realise these evaluations.
Association for European Transport