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Providing evidence to improve practice

Individual study: An ecological landscape study of deer vehicle collisions in Kent County, Michigan. Report to Kent County Road Commission, Michigan, USA

Published source details

Rogers E. (2004) An ecological landscape study of deer vehicle collisions in Kent County, Michigan. Report to Kent County Road Commission, Michigan, USA. White Water Associates Inc, MI, USA report.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Install signage to warn motorists about wildlife presence Terrestrial Mammal Conservation

A replicated, controlled, before-and-after study in 1996–2000 along roads in three townships in Michigan, USA (Rogers 2004) found that deer warning signs (including some of a novel design) did not reduce deer-vehicle collisions. In one township, the overall collision rate after installing standard and novel warning signs (55/year) did not differ significantly from that before installation (69/year). At the same time, there was no change in average rates in three townships without warning signs (after: 41–62/year/township; before: 36–62/year/township). There was no significant difference in average collision rates 200 feet either side of signs on seven road stretches that just had the novel sign design (after installation: 9/year/stretch; before: 11/year/stretch). Vehicle speeds were not lower with signage than without along one road stretch and were <0.5 miles/hour lower along a second stretch. Two warning sign designs were installed around one township between October and January of 1998–2000. Eighteen novel signs, (leaping deer and car on an orange background and text stating ‘High crash area’) were installed on seven road stretches with high vehicle-deer collision rates. Fifty-two standard signs (leaping deer on orange background) were installed on other sections. Collisions, monitored by State Police, were compared in the township before (1996–1997) and after installation (1998 and 2000) and in three townships without signs. Vehicle speeds were monitored for 15–24-hour periods before (1,124 vehicles) and after installation (1,221 vehicles) on two road sections.

(Summarised by Rebecca K. Smith)

Install wildlife warning reflectors along roads Terrestrial Mammal Conservation

A replicated, controlled, before-and-after study in 1992–2000 along roads in Michigan, USA (Rogers et al. 2004) found that wildlife warning reflectors did not reduce deer-vehicle collisions. The rate of collisions after reflectors were installed (8.5/year) was similar to that before reflectors were installed (8.2/year). This was also similar to the collision rate on another road section, at the same time, where reflectors were not installed (after: 13/year; before: 9.5/year). The total number of deer-vehicle collisions recorded was 279. In 1998, Swareflex wildlife warning reflectors were installed along three 3.2-km-long sections of road. Three additional 3.2-km-long road sections were controls with no reflectors. Collisions between 18:00 and 24:00 h, monitored by Michigan State Police, were compared before (1992–1997) and after (1998 and 2000) reflector installation.

(Summarised by Rebecca K. Smith)