tag:blogger.com,1999:blog-6470543006314152962.post2076609922919039574..comments2024-03-11T16:49:27.614+00:00Comments on The Happy Pontist: The Battle of Johnson Street Bridge rages onThe Happy Pontisthttp://www.blogger.com/profile/15252272118786667592noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-6470543006314152962.post-60077210495430424242009-11-30T10:41:40.240+00:002009-11-30T10:41:40.240+00:00Thanks for addressing a subject that bridge engine...Thanks for addressing a subject that bridge engineers find frustrating: the politics of old bridges. We all feel sad at the loss of beautiful and unique structures, but we are seldom happy with the tremendous expense of keeping them in service. <br /><br />With a highway system that was completed in the 1970s, this is an issue that I deal with on a regular basis.<br /><br />By the way, it took me several hours to figure out how a heel trunnion bascule bridge works. There's a parallelogram between the counterweight and bascule span. The counterweight is on the short top side of the parallelogram and the bascule span is connected to the short bottom side of the parallelogram. The two long sides of the parallelogram are allowed to come together, which lifts the bascule span into the air and rotates the counterweight under the now skinny parallelogram.<br /><br />I don't know why such a simple device is so hard to explain clearly. I guess a picture of the open bridge would be better than my thousand words.Anonymousnoreply@blogger.com