Cycling always sounds like a good idea. It improves your health (decreasing the likelihood of cancer or cardiovascular disease) and the planet's. It makes you happier, and might even help you focus. It's also terrifying. More than 800 cyclists died on American roads in 2015, a 30 percent increase since 2010. The 45,000 who were injured only count those who ended up in the hospital. The ranks of cyclists are growing, but potential handlebar devotees, especially women, cite fear of injury on infrastructure-deficient roads as a major reason they don't bike.

So anything that makes cycling easier or safer is a welcome development. That now includes this "bicycle stress map", of Maryland's Montgomery County. The colorful guide to the roadways of this Washington, DC suburb puts a numeric value on the scariness of streets.

Map Detail Mcatlas

Since it was published last year, the map has become both a guide and an advocacy tool. Local cyclists can plan their trip to avoid the most trafficked roads, and point to the map to show local policymakers where cycling is close to impossible. (Hearing is one thing, and seeing a map snaked with intimidating red is another.) It’s so helpful, the map just won the transportation planning award from the American Planning Association, presented today at the group’s annual conference in New York City.

To craft the map, Montgomery County staff spent a year surveying 3,500 miles of road via Google Street View. They collected data on bike lane locations and types, traffic speed and volume, the number of lanes on each road, how often cars pull in and out of parking spots, and how easy it is to cross at intersections. When they couldn’t figure it out from the office, they hit the road and broke out the tape measure. In cycling safety, the little stuff matters.

“If you’re looking at a path on the side of the road, there’s a big difference between whether the path is right next to the curb of a high-speed road, or if it might have some tree buffer," says David Anspacher, a Montgomery County transportation planner. “In some instances, we needed to measure the distance between the path and the road edge.”

Finally, they loaded that information into a formula called “Level of Traffic Stress,” a metric that’s just starting to catch on the transportation planner world. On the resulting map, level one is light and royal blue—cyclists are physically separated from fast vehicle traffic or in their own, slower zones. Even kiddos should feel comfortable biking on these. Level two is in green, where cycling lanes stand apart from traffic and car doors that could open at any moment, and where most adults would put tread to asphalt. Orange and yellow, level three, might stress you out, with bike lanes getting closer to faster traffic. Level four, in red and dark red, will force riders into mixed traffic moving at 35 miles per hour or more, and will attract only the bravest. Play with the thing online, and it can help nervous cyclists chart an optimal path to school, local libraries, or nearby public transit.

To drive home the point at city council meetings, the cartographers presented the map with cycling point-of-view videos for each level. "The reaction was very telling,” says Anspacher. “There were gasps that people would be riding in these environments.”

The planners hope the map will help the county craft a new master plan for cycling, with the goal of upping ridership and increasing network connectivity. And the county is teaching others how to make their own maps. Any place with a serious interest in improving its cycling infrastructure could build one.

“Whether it’s something that can be taken up to another area of the county and be useful to planners and other communities—things like that really hit a high mark with us,” says W. Shedrick Colman, a Savannah, Georgia-based architect and the chairman of the APA awards jury, which singled out Montgomery County for the planning award.

Americans are not crazy to be spooked on bicycles—only so many cities and towns really take cyclists into account when planning out roads. But that's changing: The number of two-wheel commuters jumped 46 percent between 2005 and 2013. Bike infrastructure is spreading, especially in forward-thinking places like Montgomery County, but not quickly enough. If growing bands of cyclists are going to stay safe on roads, give them the tools to gaze into the heart of system. Hopefully, they'll see more than red.