The Hawthorne Bridge is a six span, 1382 ft long, truss bridge with a 244 ft long lift span. It has 49 ft of vertical clearance when it's closed and 159 ft when it's open. It replaced the second Madison Bridge, which was built in 1900 and destroyed by fire in 1902 (the bridge connects Madison Street to Hawthorne Blvd. in Portland). The 440 US ton counterweights are suspended from 165 ft tall towers. It was designed by John Waddell who invented the lift bridge (see comments) and designed the nearby Steel Bridge (see the September 12th posting). However, unlike the Steel Bridge, it has only a single deck with two lanes inside the truss and two lanes and wide bicycle lanes/sidewalks outside the truss (widened and restored in 1999). The bridge cost $511,000 and it's estimated to have a replacement cost of about $190 million.
Portland's Bridges: Hawthorne Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.
Vertical lift bridges weren't invented by Waddell. Squire Whipple built several before him, and both are pre-dated by some 1868 lift bridges built in Paris.
ReplyDeleteMany thanks to the Happy Pontist for reading my blog and keeping it factual.
ReplyDeleteI noticed while writing about the Harlem River that the older bridges were swing bridges and they didn't switch to lift bridges until well into the 20th Century (to avoid having the swing pier in the middle of the channel). It probably took US bridge engineers a while to adopt the European innovation.
I wonder if the Happy Pontist can tell us why there are no movable bridges across the Thames in London or the Seine in Paris? Aren't these rivers used as shipping channels?
On the Thames, the most obvious movable bridge is Tower Bridge, which I'm sure you'll feel daft for not remembering! Downstream of that, there are only lots of tunnels and one high-level bridge (the QE2 Bridge) - see Wikipedia. Upstream, only lower-height vessels can continue, although they navigate upstream for some distance. Most of the big docks are downstream, and several of these have opening bridges across their entrances e.g. South Quay and West India Quay. The original Old London Bridge had an opening span, of course.
ReplyDeleteDon't know anything about the Seine, I'm afraid.
Lots more on the Whipple lift bridges (dating from 1872), and some others I didn't know about can be found in the ASCE Journal of Bridge Engineering.