ISU transportation data service helping State Patrol determine highway ‘deer hotspots’

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June 08, 2016
A white-tailed deer crosses a highway in a wooded area.
White-tailed deer crossing
Number of animal crashes & number of roadside deer carcasses
The four metrics (2010-14 data) are number of animal crashes & number of roadside deer carcasses per mile per year, and number of animal crashes & number of deer carcasses per 100 million vehicle miles. From Iowa Traffic Safety Data Service, ISU

It’s not news when cars hit deer, but the Iowa Department of Public Safety, which includes the State Patrol, has taken notice of the collective damage to its vehicles from striking whitetails and other animals.

That’s why the State Patrol asked an Iowa State University transportation program for assistance. ISU’s Iowa Traffic Safety Data Service (ITSDS) analyzed the locations of deer crashes and deer carcasses found along Iowa primary roads to see which highway segments are most prone to deer crashes.

The State Patrol wants to someday have alert systems in their cars to inform officers when they are entering a deer “hot spot.” You could call it a high-tech “Deer Crossing” sign.

In 2014, more than a quarter of the total damage to DPS vehicles came from hitting critters, particularly deer. Human safety, of course, also is a factor and fortunately for the State Patrol, few serious injuries have resulted from deer crashes.

Iowa ranked third in the nation (behind West Virginia and Montana) for highest risk of deer crashes, according to the 2015 State Farm Auto Insurance deer-vehicle collisions report.

State Patrol officials hope the deer-crash data can be integrated into the MACH system, which is used in State Patrol vehicles, to warn troopers when they enter a deer corridor. MACH is Mobile Architecture for Communications Handling, software that allows public safety agencies to better communicate during routine activities and emergencies. Mapping is one of the MACH features.

Data from 2010-2014
ISU’s Zach Hans, ITSDS manager, says the analysis used four metrics for each section of the state’s primary highways from 2010 to 2014. The metrics are the number of animal crashes (crash density) and number of roadside deer carcasses (carcass density) per mile per year, and the number of animal crashes (crash rate) and number of deer carcasses (carcass rate) per 100 million vehicle miles.

Hans said the study’s data, provided by the Iowa Department of Transportation, included all animals involved in vehicle crashes, but he says nearly all of them were deer.

ITSDS staff perform crash analyses for public and private groups in Iowa, using geographic information systems technology. Researchers create and provide maps that show, for example, the locations of high-crash highway curves. ITSDS services, which are free for those involved in traffic safety, are funded by the Iowa Governor’s Traffic Safety Bureau.

Hans’ team analyzed about 220 segments of Iowa primary highways and interstates. By using the four metrics, the analysis took into account areas with high deer density and high vehicle traffic. Mapping the deer hot spots is an inexact science, he says. “We could have used any one of the metrics, but we decided to include all four in our analysis for a broad picture of each road segment.”

The mapping indicates the state’s top animal crash-carcass corridors are in both urban (because of high vehicular traffic) and rural (because of high deer population) areas particularly in western, southern, and parts of eastern Iowa.

Three road corridors ranked in the top 25 in three of the four metrics (in no order):

—U.S. 18 through Marquette in Clayton County
—U.S. 218 from Nashua south to Plainfield in Chickasaw and Bremer counties
—Iowa 100 in Cedar Rapids and Marion in Linn County

Several other corridors ranked in the top 25 in two of the four metrics (in no order):

—Interstate 80 in Council Bluffs
—U.S. 59 and Iowa 175 in Ida Grove
—U.S. 218 from Charles City to Nashua
—Iowa 13 in Clayton County near Elkader
—U.S. 151 and U.S. 30 in Cedar Rapids and Marion area
—U.S. 151 in Jones County near Anamosa
—U.S. 218 in Iowa City
—U.S. 6 in Iowa County near Homestead
—U.S. 61, U.S 218 and Iowa 2 in Lee County
—Iowa 81 in Van Buren County near Farmington

Any road can produce a deer crash
“Deer crashes can happen anywhere in Iowa,” Hans explained. “So it must be determined what threshold of deer crashes along a highway segment is defined as a deer corridor and whether it holds enough risk to trigger a warning in a patrol car.”

Col. Michael Van Berkum, chief of the Iowa State Patrol, believes Iowa is the only state that is mapping roads with the highest likelihood of deer crashes. Up to now, the state’s only animal strike mitigation effort—other than reminding officers to be watchful for whitetails—has been car-mounted deer whistles, the success of which is up for debate by many drivers.

Whatever final product is developed won’t remain only with the Iowa State Patrol. “We will share our results with law enforcement agencies in other states and make it available to the public,” Van Berkum says. “It could be a good tool to warn drivers and protect the public.”

Although deer cause the most animal damage to State Patrol vehicles, other animals also can send cars to the repair garage. “It can also be car vs. raccoon,” Van Berkum says. “Raccoons can roll under the vehicles and hit the radiator and do $2,000 to $5,000 in damage.”

The Iowa Traffic Safety Data Service is part of the Center for Transportation Research and Education, administered and located at ISU’s Institute for Transportation.


Institute for Transportation, Iowa State University

Zach Hans, Iowa Traffic Safety Data Service,
Steve Jones, InTrans Communications,

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