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American Traffic Safety Services Association
ROADWAY
SAFETY
Targeted Countermeasures, Widespread Investment: Minnesota
Uses Latest Analysis Tools to Make Local Roads Safer
In Minnesota, about half of fatal and serious injury crashes occur
on local roads. Until recently, though, the investment of federal
safety funds was significantly greater on the state-owned system.
The traditional safety funding approach relied on crash rates and
other measures that give greater weight to sites with higher numbers
of crashes. However, the purpose of the Highway Safety
Improvement Program is to prevent fatal and serious injury crashes.
These crashes are much more widely dispersed and rarely produce
high crash rates at any particular location. Reducing them required
a change in mindset.
“We were headed to many rural locations and coming to the same
conclusions,” said Mark Vizecky, traffic safety support engineer for
the Minnesota Department of Transportation (MnDOT). “There
weren’t a lot of fatal and serious crashes at any one location. But,
we saw those events continue from location to location, so we came
to the conclusion that we had to think larger and different, more
systemic.”
MnDOT used data-driven safety analysis (DDSA), an Every Day
Counts innovation promoted by the Federal Highway
Administration (FHWA), to account for severe crashes on the local
road system and better allocate funding to mitigate them.
DDSA is the application of the latest generation of tools for
analyzing crash and roadway data. The tools quantify the expected
safety impacts of roadway projects, so practitioners can make more
informed project development and safety management decisions.
This lets them target highway safety investments to the most
beneficial locations. The result is fewer severe crashes.
MnDOT used DDSA tools to conduct a systemic crash analysis of
all local roads. Instead of focusing only on high-crash locations, the
analysis identified high-risk roadway features like visual traps or
intersections on horizontal curves that correlated with severe crash
types, such as roadway departure, across the whole system.
Locations with those features were deemed at risk of fatal and
serious injury crashes.
Once at-risk locations were identified, the team prioritized them for
improvement. MnDOT then chose low-cost countermeasures,
including chevron signs and rumble strips, to apply at the highest
risk locations.
The systemic analysis made it possible to move from a
reactive posture based on crash history alone to
proactively target investments to locations with the
highest risk of fatal and serious injury crashes,
sometimes before they even happen.
“Think of it like doing a health assessment with your
doctor,” said Jerry Roche, team leader for the FHWA
DDSA implementation effort. “Are you a smoker? How
often do you exercise? What is your family history of
disease? Your answers determine your risk factors for
serious illness. Similarly, systemic analysis determines risk factors
for severe crashes on roadway networks.”
To assist local agencies, MnDOT also developed road safety plans
for each county. The plans itemized at-risk locations and provided
specific, low-cost safety countermeasures to implement.
At first, not all were convinced the systemic approach was the best
way to go.
“I thought it was just another plan on the desk,” said Victor Lund,
traffic engineer for St. Louis County, Minn. “As we’ve used it more
and more, I’ve realized the power. The power really centered on the
ability to predict at-risk locations, and you can treat specific
locations that are at risk.”
To further implement the road safety plans, MnDOT shared some of
its federal funding with local agencies in proportion to the
percentage of severe crashes that were occurring on local roads.
“I think the people at the DOT here really understood that if you
want to make a true safety difference, then we have to get that
money down to the local level,” said Sue Miller, county engineer for
Freeborn County, Minn. “When people are out there on a road, they
don’t know if they’re on a state highway or a county highway. They
just know somebody got hurt on that road.”
The result has been wider application of low-cost safety treatments
to the highest-risk locations across Minnesota’s local road system.
Ultimately, the effort has made Minnesota’s roads safer.
“Between 2006 and 2010, Minnesota averaged 458 annual fatalities,”
said Will Stein, FHWA safety engineer. “From 2011 to 2015, the
average was 384 fatalities annually, a 16 percent decrease. We feel
moving toward this more systemic approach in combination with
treating both the state and local systems has played a part in that
progress.”
According to Miller, the same mission is being accomplished, and
it’s trying to make the roads as safe as possible for the public.
“We’re proactively, systemically putting that money out there to
places that it can do the most good for the least amount of cost.”
By Jerry Roche, Federal Highway Administration team leader for
Data-driven Safety Analysis
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