31 August 2016

Scottish Bridges: 57. Abergeldie Castle Bridge (after the flood)

This is the third of three flood-damaged bridges that I visited on the River Dee in Aberdeenshire during August 2016.

When I visited in 2012, the bridge was derelict and had been so for some time. At the time, I said:
I’d be astonished if the deck is still there in ten year’s time, so if, like me, you have a soft spot for derelict bridges, I suggest you visit it while you still can.
That opportunity is now gone, as the bridge collapsed during the Christmas 2015 floods.

A video on YouTube makes clear why the bridge collapsed: the entire southern bank of the river was extensively scoured away by the flood (compare my 2012 photos to see quite how much has gone).


Survival of the adjacent Abergeldie Castle was clearly a far greater concern than the bridge. The bridge's southern tower and anchorages were simply swept away along with the rest of the river bank - you can still see a remnant of the main suspension cable anchors in one of my photographs.

This video shows some of the river bank protection works in progress during January 2016, as well as the remnants of the bridge;


It's a huge shame that this bridge has gone - it was of an unusual type with two suspension cables on each side, one above the other. I'm not sure how many other 4-cable suspension bridges there now are in the UK, if any.

The Abergeldie Castle bridge was originally built by Blaikie Brothers on the instructions of Queen Victoria, at roughly the same time as she authorised them to improve the Crathie bridge discussed in my previous post. A contemporary article on the building of the Abergeldie bridge can be found in The Engineer, 7th August 1885 (page 103), and I reproduce here the accompanying bridge plans:


While preparing this blog post, I also found a photograph of the 'bridge' which predated the suspension bridge. This was a cableway structure, used to transport mostly goods and the occasional person. It's what would nowadays be called a "bucket bridge", and there are precious few of these still in use (possibly just two in Scotland):


It was unfortunate that the local planning authority took no enforcement action on Abergeldie Castle bridge's owner to preserve the structure over a number of years as it was gradually allowed to deteriorate, but nothing could have saved it from the 2015 storm.

Anyway, here are some pictures of what remains of the Abergeldie Castle bridge. The bridge pylon from the south bank was swept downstream but remained attached to the north pier, so that almost all of the bridge's wreckage now rests on the north bank.






 


29 August 2016

Scottish Bridges: 56. Crathie Suspension Bridge (after the flood)

This is the second of three damaged bridges that I visited on the River Dee in Scotland during August 2016.

Built in 1834 and modified in the 1880s, this is a remarkable and highly unusual bridge, with a bizarre set of hybrid structural supports both above and below the bridge deck. When I visited in 2012, it was in great condition.

Following the Christmas 2015 floods, the bridge has been declared unsafe and closed to users.


It doesn't appear that the bridge has suffered much damage. There is no change to the tie-back rods from what I saw in 2012.


One of the deck edge rods is loose, but this is not new.


The only significant damage I observed was where one of the deck edge rods is broken. This should be straightforward to repair.

I'd hope this bridge can be repaired and reopened without too much further delay, but as with the bridge at Cambus O'May, it doesn't provide any vital access, so it won't be a priority for the local authority.



27 August 2016

Scottish Bridges: 55. Cambus O'May Bridge (after the flood)

A couple of weeks ago, I visited the River Dee in Aberdeenshire, and returned to three bridges which I had previously seen in the Summer of 2012.

At Christmas 2015, the Dee experienced one of the most severe floods in its history, along with several other rivers in Britain. A number of bridges along the river were severely damaged, and one destroyed.

Cambus O'May Bridge was built in 1905 by James Abernethy & Co., and then substantially rebuilt in 1988. It's a very fine pedestrian suspension bridge, one of many along the River Dee. It looked good on my 2012 visit.

It's amazing that the bridge survived the 2015 flood at all, as the level of water battering the bridge can be seen in the video below:


When I visited in mid-August 2016, the damage to the bridge is clear. Unsurprisingly, it is currently closed, with no sign of any plans for repair work.


The entire structure has been bent sideways by the force of the water.


Several of the bridge hangers are missing or bent.


Most significantly, there is major damage to one bay of the main deck lattice truss, presumably due to impact from debris.


I think the most likely future for this bridge is another reconstruction, as I think it would be inordinately different to cut out and replace the most damaged section and to straighten the remainder of the bridge. That seems unlikely to happen any time soon, as the bridge does not provide critical access to anyone, and I imagine there are other priorities for limited budgets.

04 August 2016

Upper Orwell Crossing Project bridge design competition

I'm struggling to know where to start with what strikes me as one of the worst bridge design competitions to be organised in the UK for quite some time.

First, let's start with the facts.


Suffolk County Council are promoting a £77m scheme to build two new highway crossings of the River Orwell in Ipswich (A and B in the image below), and to refurbish the existing Prince Philip Lock Swing bridge (C in the image below). Working with the RIBA Competitions office, they are launching a design competition to select an architectural team, to work alongside the engineer already appointed, WSP | Parsons Brinckerhoff.


The key aim of the new bridges is to ease traffic congestion, and to promote regeneration in a riverside area which currently has very restricted transport access.

Suffolk's press release invites interested parties to submit a prequalification questionnaire by 1st September. Suffolk then intend to shortlist at least 5 teams to take part in the contest itself. These teams will submit entries by 2nd December, with a winner expected to be announced in week commencing 12th December. Construction would not start until at least 2019.

The shortlisting criteria will be something of a challenge for many very able bridge designers who may be interested in this opportunity. First, and in my view most egregiously, only architects can enter (registration with the Architectural Registration Board is a requirement, or equivalents in other countries). This is quite emphatically not a contest to find the best bridge designer, or indeed the best bridge design team, it's to provide the already-appointed engineer with a partner and skills which Suffolk CC evidently feels they lack on their own. That is, the Council does not consider their engineering consultant to be capable on their own of designing a suitable bridge for the site.

The RIBA Competitions office would support this of course - their role is as much about protection and promotion of the architectural closed shop as it is about serving any client's best interests. Some years ago, RIBA had its arms twisted by the Institution of Civil Engineers and Institution of Structural Engineers to ensure that engineers had a fair opportunity to compete in bridge design competitions (previously, RIBA were insisting that any competitors in their contests had to include a registered architect). WSP|PB will, of course, have been appointed fairly to their role, but it's simply a nonsense to suggest that there are no engineers who can design a decent bridge without the assistance of an architect (there are few, perhaps, but certainly there are some).

(RIBA's history in this area is generally poor. When I examined their track record back in 2009, I reviewed seven of their bridge design competitions, only two of which resulted in bridges actually being built. One more since then has so far fared no better (Salford Meadows), so that's a 75% failure rate.)

A further obstacle to getting the best competitors is commercial. Suffolk's information memorandum explains that they are looking for architects with a turnover of at least £1m per annum and professional insurance cover of £10m, at a stroke eliminating pretty much every specialist bridge architecture firm in the UK and limiting the field to large architectural firms for whom bridges are not a core area of expertise. For anyone who had thought the RIBA wanted to promote the interests of the small practices who make up a huge proportion of its membership, this is a quite unpleasant slap in the face.

Suffolk then go on to explain that potential competitors need to demonstrate suitable case studies demonstrating capabilities in large infrastructure projects, and information on multi-disciplinary collaborative experience, including BIM level 2 compliance. There are plenty of architectural firms who can claim this, but very few with experience applying these skills to major bridge works.

Successful hoop-jumpers will be delighted to discover they qualify for a £10,000 honorarium, which is very good by RIBA standards and will cover a small part of the costs for their site visit, interview and six presentation boards. These are to include not just one, but two entirely separate designs for each of the two main bridges, which strikes me as quite excessive, like buying one cow and expecting it to provide the milk of two.

You may wonder how the five competing architects will come up with feasible, buildable, and economic bridge design concepts, given that at this stage they will not yet have consummated the intended arranged marriage with the incumbent engineering consultant. Suffolk helpfully suggest that they could invite a friendly neighbourhood structural engineer onto their team. I will be interested to see how many engineers take up this offer, as Suffolk make it repeatedly clear that WSP|PB will be carrying out all the engineering once the project progresses for real. What engineer will pour their creativity into a contest with no carrot of a possible design appointment, only to see another engineer take on their output and gain all the credit?

In the world in which this contest lives, however, engineers are not creative, and their input is not valued. The opportunity for genuine collaborative teams to come up with exciting, attractive and practical solutions may be replaced by a good old fashioned pretty picture parade. I think almost everyone involved in this kind of work on a regular basis knows that this is not how landmark bridge design works best.


Competition entries will be evaluated for quality, appropriateness, buildability etc, and this will account for 60% of each entrant's tender marks. The remaining 40% is for a lump sum fee proposal to provide the necessary architectural services. Yes, a lump sum to undertake design even though they cannot possibly know which of their concepts will be taken forward, or how much those concepts may change during further development. The winner will be the entrant with the highest combined score, raising the very real possibility (as in other similar exercises) that the design taken forward is second or third best, if the fee is low enough.

I will be blunt: I think the way this competition has been set up flies in the face of pretty much everything that is understood about how to procure good bridge design. The prequalification criteria are calculated to exclude the talented and capable, and the promoter's attitude to the value of creative engineering design is simply disgraceful.

Am I disgruntled simply because I'm excluded from a chance to show what I can offer as an engineer? Yes, my grapes are sour, this is true. I will, of course, follow progress with great interest (first, to see whether they back away from any of the currently stated prequalification criteria). For all its flaws, I'm sure interesting designs will be generated by people capable of doing a reasonable job ...