Do types of roads cause more accidents?
- Blog Post by: Nathaniel Hood
- January 9, 2013 - 10:05 AM
The word “Stroad” has officially made it into the Urban Dictionary.
“Noun. Portmanteau of “street” and “road”: it describes a street, er, road, built for high speed, but with multiple access points. Excessive width is a common feature. A common feature in suburbia, especially along commercial strips. Unsafe at any speed, their extreme width and straightness paradoxically induces speeding. Somewhat more neutral than synonymous traffic sewer.”
Driving a car is dangerous. In fact, it’s probably one of the most dangerous activities in your day. If you’re in a collision, you run the risk of death, injury or best case scenario, property damage and increased insurance rates. Many view this as an inevitable, albeit acceptable, consequence to modern life. And that is probably true. While it’d be naive to think design alone could reduce accidents, it can help.
What makes a street safe?
I think there are a lot of elements. The design is the first thing that comes to mind, and it’s followed by speed and traffic volume. I was curious to know how the stroad held up against other alternatives. To do this, I turned to my usual test lab: my hometown of Mankato. I examined Minnesota Department of Transportation crash data & AADT (average daily traffic volume) data in an admittedly non-scientific study.
I selected seven different road segments with comparable volumes and extracted crash data from 2009, 2010 and 2011. I picked the three most recent years available. I selected four stroads, two traditional downtown streets and a medium volume road connecting the west side of town with the university neighborhoods.
The below road segments are ranked by crash ratio. The more dangerous roads are listed on top.
|Location||Road Type||Daily Volume||# of Crashes||Crashes per Day||Crash Ratio|
|Madison Ave (Victory to Hwy 22)||Stroad||16,300||165||0.15||9.24447E-06|
|2nd St (Warren to Main St)||Traditional Street||6,500||58||0.05||8.14893E-06|
|Bassett Dr (Madison to Hwy 22)||Stroad||6,000||34||0.03||5.17504E-06|
|Madison Ave (Dane to Victory)||Stroad||22,300||71||0.06||2.90763E-06|
|Adams St (Victory to Hwy 22)||Stroad||11,000||30||0.03||2.49066E-06|
|Stolzman Rd (Stadium to Blue Earth)||Road||11,800||20||0.02||1.54787E-06|
|Riverfront (Bridge to Madison)||Traditional Street||19,100||28||0.03|
[Note: This is not a scientific study. I used MnDOT CMAT and MnDOT ADT data. Speed limits on each road range from 35 to 45 miles per hour. There were zero fatalities on these roads. Most crashes were not alcohol related.]
The most dangerous road is Madison Avenue. This is Mankato’s Epic Stroad. It has 16,300 vehicles per day and 165 crashes. Compare this to Mankato’s traditional street, now a downtown thoroughfare, that has 19,100 vehicles per day and a mere 28 crashes over the same three year period.
This stretch of Madison Avenue has 14 access points within less than a mile stretch. This number alone wouldn’t be bad if the access points were traditional intersections. In the past year, Strong Towns has pointed to how these access points causes congestion. And studies have shown that these formless, high-volume arterials may also be a root cause of accidents [see Safe Urban Form and Safe Streets, Liveable Streets by Eric Dumbaugh & Robert Rae].
Contrast Madison Avenue to Riverfront Drive. Riverfront Drive is a high-volume stretch of road through Mankato’s first downtown (now marketed as “Old Town”). Make no mistake, Riverfront Drive carries a lot of vehicles. In fact, it carries more vehicles than Madison Avenue with fewer lanes and fewer crashes. It also has on-street parking, sidewalks, street trees and the buildings address the street [Important Note: This segment of town is actually fairly unpleasant. There are lots of vehicles, truck traffic, some existing industrial activity, the buildings aren’t typically well-kept and there seems to be a high rate of business turnover – but, as urban planners say, it has great bones.
Stroads aren’t always less safe. Second Street in downtown and Bassett Drive both have around 6,000 vehicles per day, but Second Street has nearly double the crashes. Of course, maybe that’s because my mom has been padding the stats (Sorry Mom! I love you, but I had to post that).
When it comes to crash statistics, 2nd Street performs poorly. It ranks behind three other local stroads, including the road behind the Wal-Mart (I have no explanation for why this is the case). Bassett Drive is a collector that connects all things suburban–auto dealerships, both failed and successful big and small boxes, misplaced townhouses, gas stations and parking lots.
Bassett Drive is excessively wide and acts primarily as a way to funnel vehicles elsewhere. Yes, it’s safer than 2nd Street (as are two other stroads examined), but what good is it if the street doesn’t add any real value to the community?
Do stroads cause more accidents?
Academic research seems to indicates they do. In my brief Mankato-oriented research, with the exception of 2nd Street, stroads had higher crash ratios than traditional streets. Admittedly, my figures may be too simplistic. Crashes vary in severity, and being that there were few fatal crashes on Mankato roads, I wasn’t able to get a good gauge on the real danger of the selected roads (that’s a good thing by the way). As a society, fatal crashes are what we care about. Whether we like to admit it or not, as long as it doesn’t slow down our commute we really don’t care if someone gets into a minor, non-serious fender bender. These accidents cause minor economic damage, but they don’t yield protestors demanding something be changed.
Safety alone isn’t the best metric of how a street is doing. Don’t get me wrong, transportation safety is absolutely important. Yet, it can’t be an end in and of itself. I’m confident that everyone reading this would rather have a town full of crash-prone Second Street’s than any of the statistically safer stroads.
I mentioned above that while it’d be naive to think design alone could reduce accidents, it can help. But it’s not just the design of the road, it’s the design of the community, the buildings and the people. Now, we can’t afford to go around and retrofit our stroads. What we can do to stroads is simple, and again, you don’t need to be a rocket scientist to understand this.
- Reduce speeds on stroads
- Add on-street parking wherever possible
- Re-stripe stroads to reduce excess capacity
It’s that simple and I guarantee it’ll work. Also, don’t text and drive.
© 2013 Star Tribune