The Anonymous Widower

Train Across the Mersey

Everybody knows about the Mersey Ferries, in part due to Gerry Marsden‘s song of the same  name. The train though crosses the river at Runcorn on one of my favourite bridges, the Ethelfreda or Britannia Bridge, depending on your preference.

The bridge lies alongside the Runcorn-Widnes road bridge, which was built in the 1960s.  I remember after a party once in Cheshire getting C to stop the car on the bridge as I was feeling unwell.  I then proceeded to puke my guts into the river below.  After that incident, she nearly didn’t marry me!  I never went to another party, where ICI’s Petrochemicals and Polymer Laboratory, were responsible for the punch.

There is an interesting footnote to the design of the bridge and that is why it is not a suspension bridge.  It is hinted at in the Wikipedia entry for the bridge.

The next idea was for a suspension bridge with a span of 1,030 feet (314 m) between the main towers with a 24 feet (7 m) single carriageway and a 6 feet (2 m) footpath. However aerodynamic tests on models of the bridge showed that, while the bridge itself would be stable, the presence of the adjacent railway bridge would cause severe oscillation.

But the true story is all about how good engineers know their subjects.

The designers of the bridge made a presentation before the design was finalised to the ICI Merseyside Scientific Society.  One of those attending was Mond Division’s vibration expert, who supposedly had a fearsome knowledge of the subject, even if he was slightly eccentric. After the presentation, he rose to his feet and said that he’d done some quick calculations and because of the proximity of the two bridges, the proposed suspension bridge would shake itself to pieces at a particular windspeed.

The bridge designer was not amused.

But ICI’s vibration expert was proved to be right in wind tunnel tests and we now have the steel arch bridge. Here are some notes on the design from Wikipedia.

The design of the bridge is similar to that of Sydney Harbour Bridge but differs from it in that the side spans are continuous with the main span rather than being separate from them. This design feature was necessary to avoid the problem of oscillation due to the railway bridge.

So good design avoided creating another Galloping Girtie.

I took a video as the train crossed and you can see the road bridge and some of the details of the railway bridge, with the large Fiddlers Ferry power station in the distance.

January 7, 2011 - Posted by | Transport/Travel | , , , , , ,

3 Comments »

  1. I used to love going over that bridge when I was a small child

    Comment by liz | January 7, 2011 | Reply

  2. There’s a video to go up, but WordPress won’t accept it yet.

    Comment by AnonW | January 7, 2011 | Reply

  3. […] In January 2011, I took a video as I crossed the Mersey and it is shown in Train Across the Mersey. […]

    Pingback by Crossing The Mersey « The Anonymous Widower | October 15, 2021 | Reply


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