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> not for shielding pedestrians from car accidents I think you're making two separate distinctions here. Bollards are not appropriate as a first defense on mot

> not for shielding pedestrians from car accidents I think you're making two separate distinctions here. Bollards are not appropriate as a first defense on motorways because they present a great risk to motorists. Bollards are however often built to shield pedestrians from car accidents (and other situations where cars enter pedestrian space inappropriately, like ram raids and vehicular terror attacks), they're just not good for protecting motorists when they do so. The most common bollards in major American and Canadian cities are explicitly specified and built to protect against fast-moving vehicles of a certain weight and center of gravity).

sandworm101 8y ago
A truck crashing into a series of bollards (a glancing blow, not a direct terror attack) turns into a meat grinder. The first bollard impact, say to the right of the front bumper, initiates a rotation. The vehicle then turns sideways to its direction of travel, becomes unstable, rolls, then impacts the next bollard. Anyone inside or anywhere near this chaos is injured. The bulk of the vehicle will eventually stop beyond the line of bollards, in pedestrian territory. This never happens, and there are no videos, because no idiot builds roads this way. The closest we have to bollards beside roads are telephone poles and trees. See this vid at 2m15s. Watch the car rotate, roll, become airborne and land on the sidewalk. https://www.youtube.com/watch?v=wMBimrlAauA https://www.youtube.com/watch?v=wMBimrlAauA More rotation after impact: https://www.youtube.com/watch?v=R3DC-Ryx7RA https://www.youtube.com/watch?v=R3DC-Ryx7RA And more rotation->roll->stop off the road: https://www.youtube.com/watch?v=pY7xo61drg4 https://www.youtube.com/watch?v=pY7xo61drg4 At the 2010 winter olympics a luge slider also illustrated this as he left the track and hit a series of uprights/bollards. He died, his body landing outside the track. Anyone standing there could have also been killed. Modern traffic safety is about keeping cars away from pedestrians during a crash. Smooth barriers without gaps keep the crashing vehicle on the road. Many are designed to redirect front wheels, literally stearing the vehicle back into the road and away from people. The goal is to slow everything gradually while keeping the crashing vehicle away from pedestrians. Barriers are even tied together in a big chain so that they can gain strength from each other, allowing very small/low barriers to redirect enormous vehicles. They might not look pretty, but they work. https://www.youtube.com/watch?v=22mzoAkJJBQ https://www.youtube.com/watch?v=22mzoAkJJBQ https://www.youtube.com/watch?v=j-HevN1bzbA https://www.youtube.com/watch?v=j-HevN1bzbA
- dingaling 8y ago
  But you can't use ungapped barriers in town centres or other areas of arbitrary pedestrian flows. Hence, bollards will always have a niche.

sandworm101 8y ago

A truck crashing into a series of bollards (a glancing blow, not a direct terror attack) turns into a meat grinder. The first bollard impact, say to the right of the front bumper, initiates a rotation. The vehicle then turns sideways to its direction of travel, becomes unstable, rolls, then impacts the next bollard. Anyone inside or anywhere near this chaos is injured. The bulk of the vehicle will eventually stop beyond the line of bollards, in pedestrian territory. This never happens, and there are no videos, because no idiot builds roads this way. The closest we have to bollards beside roads are telephone poles and trees. See this vid at 2m15s. Watch the car rotate, roll, become airborne and land on the sidewalk. https://www.youtube.com/watch?v=wMBimrlAauA https://www.youtube.com/watch?v=wMBimrlAauA More rotation after impact: https://www.youtube.com/watch?v=R3DC-Ryx7RA https://www.youtube.com/watch?v=R3DC-Ryx7RA And more rotation->roll->stop off the road: https://www.youtube.com/watch?v=pY7xo61drg4 https://www.youtube.com/watch?v=pY7xo61drg4 At the 2010 winter olympics a luge slider also illustrated this as he left the track and hit a series of uprights/bollards. He died, his body landing outside the track. Anyone standing there could have also been killed. Modern traffic safety is about keeping cars away from pedestrians during a crash. Smooth barriers without gaps keep the crashing vehicle on the road. Many are designed to redirect front wheels, literally stearing the vehicle back into the road and away from people. The goal is to slow everything gradually while keeping the crashing vehicle away from pedestrians. Barriers are even tied together in a big chain so that they can gain strength from each other, allowing very small/low barriers to redirect enormous vehicles. They might not look pretty, but they work. https://www.youtube.com/watch?v=22mzoAkJJBQ https://www.youtube.com/watch?v=22mzoAkJJBQ https://www.youtube.com/watch?v=j-HevN1bzbA https://www.youtube.com/watch?v=j-HevN1bzbA

dingaling 8y ago
But you can't use ungapped barriers in town centres or other areas of arbitrary pedestrian flows. Hence, bollards will always have a niche.