23 September 2014

Yorkshire Bridges: 7. M62 Pennine Way Footbridge

This is the last bridge from various trips around the North of England that I'll cover here for a while. I have various bridges in London, Wales and France that I want to get onto next.

The Pennine Way Footbridge forms part of a set with Wentbridge Viaduct, Droppingwell Footbridge, Smithy Wood Footbridge, Needle Eye Bridge, and Scammonden Bridge. The link is that all were designed by the highly productive and creative West Riding County Council during the 1960s as part of major expansions of the motorway and A-road network.

The footbridge was built to preserve a walking route over the M62 motorway, where the highway enters a deep cutting on the western edge of the Pennines. Approaching it along the footpath from the south, you can hear the motorway before you see the bridge, a sound much like a waterfall in a canyon. The bridge is glimpsed across the moors but not properly seen until close to the crest of the cutting, where the dull roar of sound reveals itself to be a cascade of cars and lorries tumbling westwards towards Manchester.

Spanning 67m, the facts of the bridge are prosaic. It is a three-hinged reinforced concrete arch, with prestressed propped cantilevers carrying most of the deck. Similarities with the Droppingwell and Needle Eye bridges are obvious, and there's another very similar bridge near Leeds which I hope to visit on another occasion. The Swanscombe Cutting Footbridge in Kent is another point of comparison, the only bridge of this type in Britain which holds Listed status.

I think the Pennine Way bridge is the only example of its kind (in the UK at least) where the deck follows a sag curve. At first sight, this is a disconcerting choice, especially viewed from the motorway, but it makes perfect sense when seeing the footpath in context. It's interesting to wonder whether, if it had been built a few years later, a stress ribbon solution would have been considered, as was done within a decade at Hope in Derbyshire.

I find the bridge to be extremely elegant. The counter-curved lines of the arch and the deck sit well together, and all the concrete elements are particularly slender. The legs of the arch split below the deck to provide lateral stability. The bridge is not beautiful from all angles, but it's hard to find much to fault with it. It is little more than it needs to be, and its geometry has been chosen with great care.

The parapet is made of aluminium, and has lasted far better than the painted steel parapet on the Scammonden Bridge (the next bridge above the M62 to the east). Because the deck falls towards its centre, the deck includes a drainage slot above its central hinge, which presumably drains to ground through the arch legs.

The bridge throws a sharp and striking shadow across the landscape. This is a supremely difficult location for a bridge, acting as a gateway between Lancashire and Yorkshire, and between the slopes to the west and the broad moorland to the east. It sits well at such an aesthetically sensitive location.

Perhaps the only thing I would criticise is not the bridge itself, but the careless positioning of motorway furniture around it. In particular, a large traffic sign on the eastbound approach spoils views of the bridge along the motorway. The bridge is not unique in this respect, with the Highways Agency and their forebears generally giving little or no consideration to how the motorway as a whole system should be treated aesthetically.

Further information:


Bridge Ink said...

Your statement, " a large traffic sign on the eastbound approach spoils views of the bridge along the motorway." zeroes in on one of my pet peeves. There is a beautiful new cable-stayed pedestrian bridge over Interstate 5 at Eugene, Oregon. Designed by an internationally proclaimed engineer, Jirí Stráský and uglified by the hanging of traffic signs. How could they?

The Happy Pontist said...

Are those actually on the bridge?

The Happy Pontist said...

I think this link should show the M62 one properly: https://maps.google.co.uk/maps?ll=53.629276,-2.029284&spn=0.000013,0.010568&t=h&z=17&layer=c&cbll=53.629285,-2.02904&panoid=so4AQFDZFKvZTiPPVNvr3w&cbp=12,86.5,,0,2.83

Bridge Ink said...

Yes, unfortunately the signs are actually on the bridge. Here is a view that catches the bridge without the ugly signs.


But the thousands of viewers on the highway don't get that nice angle.

The Happy Pontist said...

I can see why it's your pet peeve, those signs are really annoying!

Imre said...

This issue of sign placement vs. aesthetics is more or less part of a general conflict between architects, structural and other engineers.

In my opinion, the awareness towards the aesthetics of their structures is quite easily raised in structural (inclusive bridge) engineers, even though it is rarely part of their education. This is especially true for general building constructions where the archictect takes the lead designer's role, and the structural engineer has to adapt to the architect's vision. A favourable instance in bridge design is when architectural input is sought for the bridge.
In my experience, this is a very fruitful form of cooperation, since the bridge engineer has to answer questions on why the structure should be constructed in a certain way and why other forms are less feasible. This spurs "structural" thinking, but also raises awareness to "non-structural" or structurally less important details.

On the other side, - again in my experience - traffic technicians, who deploy traffic signs, and building services engineers (especially HVAC) care only little about the aesthetics of their work - partly since this is not part of their education, and partly since they are not required to look at their "products" from this point of view. In the case of building services engineers, where an architect is in charge of the building, this results very often in "concealment" of the HVAC equipment, while in some cases "mistakes" happen if the architect misses to review the design - see e.g.
In the case of roadways and motorways, where a roadways engineer is usually in charge, aesthetics is a minor aspect, since they are usually also less concerned about aesthetics. This leads then to such regretful results as discussed before.

Knit Nurse said...

That's a beauty of a bridge! I'm sure I've seen it from the motorway but looks like the walker's view is even better.