tag:blogger.com,1999:blog-3858936825205287587.post1121096703665466051..comments2023-10-09T02:23:07.545-05:00Comments on Bike Walk Tennessee: Let's Be Creative and Save LivesAdminhttp://www.blogger.com/profile/18183903690670393144noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-3858936825205287587.post-41495420110577445132010-12-16T09:24:06.409-06:002010-12-16T09:24:06.409-06:00Excellent point about the fact that excessive spee...Excellent point about the fact that excessive speed does kill. The engineer is right in that simply reducing the speed limit does not tend to change driver behavior; but road redesigns do. Depending on the nature of the traffic on the road, a road diet may or may not work. Generally, 4 to 3 road diets work on roads up to 20,000 vehicles per day, and work especially well when there is much turning as opposed to through traffic. If the traffic is spread out over the day, then the 20,000 figure goes up. OTOH, if the traffic is overwhelmingly through traffic, then a 4 to 3 road diet may create problems.<br /><br />Interestingly, I remember reading about how the overall throughput of a road in terms of net traffic moved follows some sort of inverted U curve with regard to speed. Go too fast, and capacity drops because cars need to be spaced out too much. Minimizing delays at intersections can easily compensate for lower overall speeds on surface streets, which is why roundabouts so dramatically improve traffic flow at busy intersections.<br /><br />The video reference is an excellent one. I'll quote it for everyone's reference.<br /><br /><i>When a pedestrian is hit at forty mph, there's a 70 % chance they'll die. At thirty mph, there's an 80% chance they'll live</i><br />New York City Department of TransportationNelson Chenhttps://www.blogger.com/profile/02242732764005940428noreply@blogger.com