Implementing a collision survey protocol over the national road network Review and prospects after two years of monitoring

The Western France Interdepartmental Road Department (DIRO) manages a 1500 km road network, of which 1200 km is dual carriageways. Mainly located in Brittany, these infrastructures are old and require an upgrade to address today’s environmental concerns, especially to integrate the issue of ecological continuums.

In order to improve its knowledge in terms of the movement of animals and the major accident spots, DIRO has decided to implement a register of collisions between wildlife and vehicles throughout its network.

Since January 2014, each patrol has had to list collisions noticeable from their vehicle, at least in waterproofed areas, without actively looking for road kill on each part of the road. Priority is of course given to the safety of the patrol officers, who need to survey while fully respecting the rules of the road. In case of identification difficulties, it is considered that even if only the species group is known, this already provides an interesting indication (e.g. amphibians, mustelids). However, a particular protocol is followed if there is a doubt about the identity of the otter. In this case, the patrol officer is asked to take a picture and keep the animal until formal identification of the species and the removal of tissue for subsequent analysis. Each animal seen is recorded very precisely (date, track, road position + x-axis), and the data is then centralized monthly for layout, mapping and georeferencing of the data.

The involvement of 28 service and intervention centres, assigned to cover the entire network, is complete with almost 100% returns.

In 2014 (the only full year available during the writing of this summary), there were well over 5,000 listed collisions (3.3 collisions / km / year) which represent (using an average weight per species) 34 tonnes of biomass ... Foxes and birds pay the highest price (20% of all collisions) followed by rabbits (11%), badgers (8%), and roe deer (6%).

Despite the lack of historical data, trends have emerged including an annual breakdown of the most impacted species corresponding to periods of high activity (reproduction, rearing young, swarming, migration).

With the accumulation of data over the years the trends will become clearer and explanations for disparities in observed results between service and intervention centres will emerge.

CEREMA (Centre for studies and expertise on risks, environment, mobility, and urban and country planning) is assisting the DIRO in the implementation of this action, from the writing of the collision survey protocol to participation in interpreting the results.

In 2016, it will be commissioned by the Directorate General of Transport and Infrastructure and the Sea (DGITM), on the DIRO network, to assess the representativeness of the collision survey methods used daily by DIRO agents by carrying out monthly reviews of two homogeneous areas of 50 km. The aim is to work on the overall method, in particular as regards to the detection of major conflict spots using the data collected by each method.

A partnership agreement between the Natural History Museum and road network managers may be signed.

survey protocol;traffic mortality; prospect monitoring