Torridge Bridge - Virtual Reality Model

This version of the page is for Cambridge University use. It shows VR images but the links to the source files will not work. Those are only available within the .cam.ac.uk domain.

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This page has been constructed by James Stevenson and Chris Burgoyne. The VR model was constructed by James as part of his 4th year undergraduate project in 2003. We are grateful to Steve Denton of Parsons Brinckerhoff for detailed plans of the bridge, from which the VR model was built, and for some of the images displayed here.

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The Torridge Bridge carries the A39 road across the river Torridge in North Devon. It was designed by ... and built by ... in 19... It was built by balanced cantilever construction, with internal cables. The bridge is about 2 miles north (downstream) of the town of Bideford, which it bypasses.

The old bridge in Bideford which has been in use for hundreds of years. It has been widened and repaired on many occasions, and provides severe impediment to flow of water, as well as almost blocking river transport.

Corner detail of one unit showing ducts and anchorage
	Stockpiled units

Placing units near pier
	Span nearly complete

Virtual Reality Models

There are three virtual reality models described below.  They require a VRML2 viewer to be available as a plug-in to the web browser.  The models here were developed and tested using the Cortona Viewer which can be downloaded free from the net, but the files should be compatible with other VRML2 viewers.  The programs also require that Java be enabled on the viewing computer.  All files remain copyright of Chris Burgoyne and Cambridge University and are made available here for teaching purposes.  They should not be passed on to third parties.

To run the models, click on the links below.  It is probably better to open them in a new viewer so that the instruction page can be checked.  The models are large and can take several minutes to download and mount, depending on the speed of the internet connection and your computer.  Do not attempt to move around the models until loading is complete; the results otherwise are unpredictable and the viewer can hang.  It may be sensible to adjust the speed of motion - when moving around the whole site, select a faster speed - when moving around inside the bridge a slower speed is more appropriate.  If the viewer supports optional collision detection, switch it off so that you can pass inside the bridge.

Overall VR model, which shows the outline of the complete bridge.  The model includes several fixed views and a flyover, which passes one way along the bridge, and then returns through the box girder. Click on the section of any cantilever nearest the pier to render that cantilever transparent. Clicking on the segment furthest from the pier will make the cantilever opaque once more. Click on the base of the pier in the middle of the river to initiate the flyover sequence. The viewpoint on initiation of the sequence must be the viewpoint on opening the file. If the viewer has moved then pressing the ‘restore’ button at anytime during the flyover will realign the viewpoint.

Boat view
	Concrete can be made semi-transparent to show internal structure

The Cable Model shows a limited part of the bridge in detail, including all the cables. The cantilevers can be made transparent / opaque by clicking on the relevant segment, as above.  There are several predefined viewpoints. These can be cycled through by using the arrow buttons at the bottom of the screen or can be accessed directly by clicking on the word ‘view’ between these buttons and selecting from the list.

In the cable model the cantilever cables have been shown in red and the continuity cables shown in green
	Both horizontal and vertical cable profiles are correct

The final model shows the construction sequence.  The launching gantry is transparent and the segments can be seen being brought forward, rotated and lowered into position.  The segments are made trasparent to show the cables being introduced, and then opaque for realism.  When the span is complete the continuity cables are introduced and the girder moves forwards.  One slight mistake - our bridge was built from the east bank - the real bridge was built from the west. To initiate the construction sequence the viewer must move forwards. Once inside a specified boundary (just in front of the viewer’s starting position) the sequence will begin.

Segment being transported past a pier
	Partially transparent image

Virtual anchorages	Real anchorages