In the United States, only 1 percent of trips are made by bicycle. In the Netherlands, which has only 1/18 of the U.S.’s population, that number is close to 26 percent. With so many bikes on the road, Dutch company TNO is working on a car airbag that deploys outside the vehicle to reduce bicyclist injuries. Upon impact, the airbag, housed under the hood, inflates to cover parts of the windshield and cushion a biker. In tests last November, engineers drove a track-guided car into a dummy on a bike at 25 mph, the average speed of a crash. Accelerometers in the dummy’s head and neck and pressure sensors embedded in its limbs indicated brain damage and broken bones. Dummies in collisions with the airbag had fewer and less severe injuries up to 45 percent of the time.