Data Collection Projects
Large roads are great for moving vehicles through an area. However, if you are a pedestrian, getting across a wide, busy, high speed road can be daunting. No one wants to play Frogger in real time with real consequences. It is for this reason that pedestrian bridges are sometimes built.
Pedestrian bridges allow for pedestrians and bicyclists to safely cross a busy road without conflicts. One significant barrier to the use of a pedestrian bridge is the distance is added to the pedestrian/bicyclists route. Because of the need to get up above cars and trucks (about 20 feet above the road), straight or spiral ramps are typically used that can be several hundred feet long depending upon the surrounding terrain. Therefore, an important question to ask is which is more valuable to the average pedestrian/bicyclist – a safe crossing using the pedestrian bridge or the time-savings of crossing the road at grade?
Kimley-Horn and Associates needed an answer to this question for one of their projects and contracted with Traffic Data Inc. (TDI) to help determine the answer. TDI used video cameras at an intersection in Columbia Heights, Minnesota that had a pedestrian bridge over a busy four lane divided road with turn lanes. At this signalized intersection, the major road travels north-south and the pedestrian bridge provides for east-west travel on the south side. There are no marked east-west crosswalks across the major road. Other characteristics of the intersection:
One camera was pointed at the pedestrian bridge access on one side of the road and another camera was focused on the intersection. This set-up allowed all pedestrians crossing in the area to be counted.
Rainy weather struck the area on the originally planned day of recording. So the cameras were left out to record the next day when the weather was clear and more pedestrians were walking around. Using this video from the COUNTcam, 24-hour counts were completed of the pedestrians/bicyclists using the pedestrian bridge and crossing at the intersection.
From this 24 hours of data collection, approximately 44% of pedestrians and bicyclists crossed using the pedestrian bridge. That means the majority picked convenience over safety in this case.
This result was not surprising to us. Most people tend to view the extra distance as a burden that will cause too much delay to them. With the signal providing some gaps in the traffic flow and no physical barriers to prevent the at-grade crossing, the safety risk may seem small to a lot of pedestrians.
For this location, and other locations considering pedestrian bridges, the two ways to increase its use are making the bridge more convenient or making the at-grade crossing less convenient. Bloomington, Minnesota has a great example of making the bridge more convenient where the land is built up around the road and the natural path of the trail leads pedestrians up to the bridge. Discouraging the at-grade crossing typically involves plantings, fences, and redirecting the trail to make getting the road and across it more difficult. It will be interesting to see what changes are made in at this intersection to encourage the use of the bridge.