25 November 2014

Bristol Bridges: 3. Valentine Bridge

I'm nearly caught up on a backlog of bridge visits. The next two are both in Bristol, where I've previously covered Clevedon Pier (yes, I know that stretches the definition of "Bristol" and "bridges") and Pero's Bridge.

Valentine Bridge was built in 2000 by Alfred McAlpine, to a design by Atkins. The steel cable-stayed bridge carries pedestrians and cyclists across Bristol's Floating Harbour close to Temple Meads railway station.

As with the nearby Meads Reach footbridge (for which, see the next post), the bridge was privately funded and is privately owned.

The structure is S-shaped in plan, with a triangular cross-section framed truss deck. The upper and lower chords are circular steel tubes, connected by I-section struts in a Vierendeel arrangement.

This is not a good bridge.

It seems evident that the client must have wanted a "landmark" bridge of some sort, hence the mast, cables, and general layout. However, little effort seems to have been put into creating an efficient or well balanced structure. Of the four back-stay cables, two are so slack as to appear un-stressed, presumably a result of a cable layout which appears baffling when viewed from overhead. A balanced layout could have been achieved with fewer cables working more effectively.

Some of the cable detailing also looks a little awkward, perhaps cheap, especially the anchor detail to the deck.

The curved stainless steel parapets seem to be trying a little too hard, with an over-pronounced arc to the parapet posts. The abutment at one end, a mix of bold brick and prison-fencing (to guard the bearings), is quite unfriendly, as are the (pointless) anti-cycling barriers which block the walkway entrance.

Most annoying of all is the decking, which seems to have been fixed incorrectly, making a pronounced clattering sound each time someone crosses the bridge. If you watch the video below carefully, you can see the deck planks actually bouncing up and down.

Further information:


Anonymous said...

Valentine's bridge has been closed for repairs most of December 2014 with people using the road bridge to the W or Meads Reach bridge to the E depending on where they want to end up.

But there's been no sign of workmen after the fencing went up and no notice with timescale involved. I just hope they are replacing the rattly decking which has always been noisy.

Anonymous said...

If you are a bridge designer, then you will know that budgets get constrained and compromises often need to be made. You start with a Bentley and end up with a Mondeo. Still good, but not what it could've been.

If only two 'cables' (they are rods) were used the mast would fall down. Three are under continual load, one is for load reversal and therefore has a tendency to show that it is unloaded by sagging under it's self weight.

It was designed as pedestrian/cycle dismount bridge, so the barriers were put in deliberately to force the said dismount. Twenty years ago the cycling fraternity were not as gladiatorial as they are now.

Your critique comes across as trite, I'm afraid

The Happy Pontist said...

What utter nonsense. If some cables are "only" for load reversal then you should arrange the bridge geometry and weight so that there's enough prestress that those cables never go slack. It's an amateurish design all round.

Anonymous said...

Not if the cable anchor points were preset before the optimum scheme was completed.