Tuesday, July 31, 2012

Sharing the Road: Optimizing Pedestrian and Bicycle Safety and Vehicle Mobility

If you've got a few hours to spare, check out Sharing the Road: Optimizing Pedestrian and Bicycle Safety and Vehicle Mobility a report released by MDOT late in April. At 197 pages it's a pretty wild ride. I haven't been able to get through much more than the executive summary in Part 1 and the Best Design Practices in Part 6, but from what I have been able to glean, roundabouts are objectively awesome. Here are some choice cycling facts from the report:
Youth (ages 5-15) involvement in bicycle crashes in Michigan is higher than national statistics: 32.4% compared to 26.8%.That means nearly one-third of all young people in Michigan are involved in a bicycle crash and one-forth of those (25.3%) are fatal/serious.

In all other age classifications, Michigan’s rate is lower than the national data, except for those 65-74 years old.

Men are involved in 81% of all fatal bicycle crashes in Michigan. Bicycle crash locations are nearly evening spilt between intersections and non-intersections (49% to 51%).

Despite the perceived safety of a signalized intersection, almost half of all fatal and serious injury bicycle accidents (48.9%) took place at signalized intersections.

More than half of all fatal/serious injury bicycle accidents took place on two-lane roads (56.6%), followed by five-lane (13.8%); four-lane (12.9%) and three-lane (9.7%).

Together, 25 and 30 mph streets (neighborhood and downtown streets) accounted for 75.5% of all bicycle crashes, but the majority of fatal bicycle crashes took place on streets/roads with a speed limit of 45 mph or greater even though they comprised only 19% of the crashes.

Between 3:00 p.m. and 6:00 p.m., 27.2% of fatal and serious bicycle crashes took place, followed by 6:00 p.m. to 9:00 p.m. (21.8%); and 12:00 p.m. to 3:00 p.m. (18.5%).

The day of the week made almost no difference for fatal and serious injury bicycle crashes in the 2005-2010 time frame, ranging between a low of 151 on Sundays to a high of 220 on Wednesdays. The average is 192 and the weekday average is 205.2.

More than two-thirds (71.2%) of all fatal and serious injury bicycle accidents took place during daylight hours and 89% where when the pavement was dry.

Alcohol was not involved for the motorist or bicyclist in 70% of the fatal and serious injury crashes.

Pretty interesting. Here are some of the proposed solutions for improving bicycle and pedestrian safety:
Roundabouts showed an overall decrease in all types of crashes by 35%, injury crashes by 76% and fatal crashes by 89%. They also are one of the most expense improvements, costing between $250,000 and $500,000.

Road diets reduced all crash types anywhere from 14% to 49%.

Raised medians reduce all crashes by 40%, and by as much as 69% at unsignalized intersections.

Bike lanes can reduce bicycle crashes by 50% and are most appropriate on streets with average daily traffic volumes exceeding 3,000 and posted speeds between 25 and 35 mph.

Buffered bike lanes are preferable on roadways with speed limits exceeding 35 mph.

Shared lane marking (sharrows) were found to increase bicyclist visibility to motorists, reduce the occurrence of wrong-way riding, and riding on sidewalks.

Green, high-visibility bike lanes will be added to the next version of the Manual of Uniform Traffic Control Devices (MUTCD). Where tested, these have been shown to improve safety through a variety of measurements.

So those sharrows do something after all.

Hat Tip: Rust Wire


  1. The roundabout data is interesting, though there were several variables in their case study. Do you suppose it's because you only have to look one way at a time for roundabouts (left when entering, right when exiting)?

    I was hit on my bike for the first time this year by someone rolling through a stop light during a right-turn-on-red, which the study said had no effect on cyclist safety. In the driver's defense, I was wearing a bright green tie with matching socks and a blue sweater vest, which I believe is a defense to anything short of treason.

  2. What's a "road diet"? (second proposed solution)

  3. @Erin a "road diet" would be going from a 4 lane road to a 3 lane road with a dedicated left turn lane in the center and bike lanes on the sides.

    @J I think one reason roundabouts are safer is because of reductions in speed and angle of impact. It also probably helps that you only need to look one way.

    1. You only need to look one way, except for, of course, all those pedestrians that roundabouts are safer for.

  4. Lots on interesting stuff there, but there's one misleading sentence in your summary:

    That means nearly one-third of all young people in Michigan are involved in a bicycle crash and one-forth of those (25.3%) are fatal/serious.

    Ben, Your reading of this isn't right... one twelfth of all young people in Michigan are not seriously injured or killed in bicycle crashes! The chart in question show the age distribution, not the crash rate.

    2010 Census shows ~1.3 million population between 5 and 14 in Michigan, figure 23 in part 2 of the report shows ~300 fatal and serious injuries in ~that age group (per year?, or 2006-2010?) so fortunately the rate of serious injury or fatality is ~1/5000 rather than 1/12.

  5. @Anon,

    Thanks for the analysis. To be honestly, I just copied the bullet points from the executive summary. It looked fishy and I should have fact checked a little better.

  6. I know my view isn't popular but I believe in thus: Bikes have no business being on the road with cars. They should be on the sidewalks. If a car hits them it is more likely to be fatal or cause serious damage. If a biker runs into a person..damage but not as serious. And there is space on the sidewalk for bikes to maneuver around people and vice versa. If a car did that it could cause an accident.