Merseyside Bridges: 3. Venetian Bridge, Southport

There are three bridges which cross the artificial lake in Southport. I've already covered the first two, and the third is here for completeness rather than special interest. It has three sections, separated by two islands, all built in 1931, with concrete main structural members supporting a timber deck. They were refurbished in the early 1990s.

Further information:

• Google maps / Bing maps
• Historic development of Southport and its seafront [PDF]

Merseyside Bridges: 2. Marine Way Bridge, Southport

Marine Way Bridge lies right next to Southport Pier, the subject of my last post. The contrast is remarkable. It's perhaps unusual to find a landmark bridge of this size located quite so centrally in a predominantly low-lying urban area.

Opened in 2004, Marine Way Bridge carries a local road across an artificial lake, which dates back to 1887. As well as improving highway links, it sought to provide a "catalyst for future investment and regeneration" in what is a somewhat run-down seaside resort. A previous road bridge had been demolished 15 years earlier, and the new bridge restored a key connection between the seafront and the main part of the town.

It's an asymmetric cable-stayed bridge, with the deck supported from an A-frame pylon sitting to one side of the lake channel. It has a main span of 80m, and is 150m long and 18.5m wide. The tower is 56m tall. Both the deck and the pylon are in reinforced concrete.

The bridge was designed by Babtie (now part of Jacobs) with Nicol Russell Studios, and built by Balfour Beatty. It shares a number of similarities to Nicol Russell's previous Leven Crossing bridge at Glenrothes. The design was reportedly the winner of a competition, although I've not found any details on that. The bridge won the ICE's North West Merit Award in 2005.

Seen in elevation, the tower gives the impression it is taller than it needs to be, with the forespan cables steeper than is normal in a cable-stay bridge. A 40m tall tower would be sufficient to get the average cable angle at 45°, which is more conventional. It's not clear whether the height was chosen to reinforce the structure's landmark status, or to reduce the horizontal forces in the deck, and hence on the foundations.

I never really like A-frame pylons, visually. I can't quite figure out what it is about them that I dislike. At Marine Way, an effort has been made to shape the head of the tower, but the legs themselves are still a bit too bland.

The underside of the deck is more successful, taking the form of a concrete ladder beam with two large edge beams and a series of crossbeam ribs. It's more attractive than the underside of many bridges, but from an engineering perspective, the crossbeams seem unnecessarily deep, and the whole thing just too heavy - a steel structure would have considerably reduced the cost of the foundations.

From above, the decision to anchor the cables directly into the edge beams, rather than through small cantilever stubs, seems a little unfortunate. It creates a level platform likely to attract people to hop over the main parapet, and hence needs protecting with awkward cables, as shown.

On the whole, it's certainly not an unattractive cable-stay bridge, but it does strike me as a little out of place, especially set against the other bridges which span this artificial lake (I covered one last time, and the other will be my next post). There seems no pressing reason to have to span the lake without intermediate piers, and an attractive bridge could have been designed which was far less expensive. Whether the bridge fulfilled its aim to act as a catalyst for regeneration, although looking at the surroundings, I doubt there is much that a more modest bridge wouldn't also have facilitated.

Further information:

• Google maps / Bing maps (image taken during construction)
• Structurae
• Aerial photo taken during construction
• Sefton Council
• Stirling Lloyd

Merseyside Bridges: 1. Southport Pier

Okay, before embarking on a set of reports from a tour of Merseyside, I ought to point out straight away that I'm using the term in its broadest sense, a sort of Greater Merseyside which stretches from Southport in the north, along to Warrington at its easternmost extremity. I know locals get touchy about these designations, but really, it's just an excuse to go visit some interesting bridges and lump them all together here, okay?

I think Southport Pier is the first pier that I've featured here. Is a pier a bridge? A pier is clearly bridge-like in its structural form if not in satisfying the usual definition of "spanning an obstacle". Southport Pier, however, makes the decision easy, as not only does it jut out into the sea, but part of it also spans an artificial lake. So it's definitely a bridge.

It was designed by Sir James Brunlees, and opened in 1860. At 1108m long, it's the second longest pier in Britain, although a large part of its length is over land. It was even longer in the past, having been extended first in 1864, and then again in 1868. From the point of view of engineering history, its use of jetted piles was pioneering, but I'm afraid I just can't get that bothered about piles.

It was proposed to be demolished in 1990, but saved and Listed (Grade II) following a vigorous campaign. I find it hard to fathom why a seaside resort like Southport would want to demolish one of its main attractions, and I think they were perhaps swayed by unrealistic estimates of the cost of maintenance (a figure of £250,000 for repainting every 5 years was quoted).

One of the methods used to help save the pier was by a campaign to sponsor the planks in the deck, the legacy of which is clearly visible via individually named plates embedded in each plank.

The pier is described as having been refurbished, with the work completed in 2002, but it's clear that large parts of it were completely rebuilt. Looking close up at the main lattice beams, it's apparent they are welded, which clearly isn't part of any original construction. The current aerial image shown at Bing (linked below) also makes clear how extensive the rebuilding was. I guess the cast iron columns and wrought iron tie bar bracing may be original, and for me these are the main attraction of the pier - their delicacy is what makes it an attractive structure, as the modern decking and parapets, and the awful arched lighting supports, are certainly not very appealing.

The pier also carries a unique battery-powered tramway, added in 2005. The links below provide far more information on the pier's history than it would be sensible to recount here.

Further information:

• Google maps / Bing maps (image taken during reconstruction)
• Wikipedia
• Structurae
• Engineering Timelines
• the-pier.co.uk
• National Piers Society
• The Heritage Trail
• Southport Pier Trust article on restoration
• Civil Engineering Heritage: Northern England (Rennison, 1996)