The Happy Pontist: Glasgow

Showing posts with label Glasgow. Show all posts

03 February 2019

Separated at birth?

Glasgow City Council has published the design for a new bridge across the River Clyde connecting Govan and Partick, next to the Riverside Museum. The bridge is to be 110m long, with an opening span of 63m, and a swing bridge has been chosen so that the bridge can operate in high winds.

The bridge has been designed by CH2M Hill (now part of Jacobs), who in their previous incarnation Halcrow have previously delivered quite a few Clyde crossings. It's expected that a planning application will be made this summer, with the intention to complete construction in 2021.

The budget has been previously stated as £10m, but I don't know if that's accurate.

So ... spot the difference.

The top picture is the new Govan-Partick bridge. I'm sure any similarity to the Puente de la Mujer in Buenos Aires, shown in the second picture, is entirely coincidental.

I was especially amused to see that the artist tasked with visualising Glasgow's new design adhered so slavishly to their brief (presumably "copy this one please, pal") that they even included a sailing ship.

Or maybe this was their source material:

That one, of course, is in Dublin, and does at least have some back-stays unlike the Buenos Aires span or its Glaswegian clone. What is it about these bridges and sailing ships, anyway?

I don't think there's anything else I really want to say about the Govan-Partick bridge right now, so here are some more visualisations, and a rendered video:

03 July 2010

Scottish Bridges: 12. Clyde Arc

Continuing west from Kingston Bridge, the next span over the River Clyde is the Clyde Arc (previously known as the Finnieston Bridge). This is the last bridge I visited on my short trip along the river.

The £20.3m highway bridge has a 96m main span, suspended by steel hangers from a steel box-section arch passing diagonally across the bridge deck. The arch is diamond-shaped in cross-section. The bridge was designed by Halcrow, and built by Nuttall with Watson Steel. It opened in 2006.

The design would seem to be directly inspired by the Hulme Arch Bridge in Manchester, as were Bolton's Newport Street Bridge and Edinburgh's Gogarburn Bridge (which I'll feature another time if I can dig out any photos). Essentially, it's irrational, because the arrangement leads to very high lateral bending moments in the arch, which govern the entire design. The attraction is the strong visual identity, especially when the arch is viewed from the side, where the hangers appear to cross in a network pattern.

I was a bit surprised by the sheer massive scale of the Clyde Arc - it's by far the largest span of its type (Hulme is second at 52m, while Newport Street spans only 35m). From a distance it looks almost delicate, but up close it's quite overbearing. I found it simply too gross in scale for the context.

The bridge is probably best known for its unfortunate history since opening. It was closed in January 2008 when a hanger failed (under minimal load) and fell onto the deck, reopening in June 2008 after all the hanger connectors were replaced. There seems little doubt that the cast steel connectors had an inadequate toughness, but since Watson took the hanger supplier Macalloy to court for a £1.8m claim, little further information has been published. As with many modern bridge failures, it's unfortunate that the legal process delays or even prevents the wider engineering community from seeing what lessons are to be learned.

Further information:

02 July 2010

Scottish Bridges: 11. Kingston Bridge

Heading west from the Tradeston Bridge, the next bridge over the Clyde in Glasgow is the Kingston Bridge.

When it opened in 1970, it was reportedly Britain's second longest spanning balanced cantilever hollow box girder prestressed concrete bridge, with a 143m main span. It was beaten only by the Medway Bridge, which had achieved a 152m span in 1963. (Still longer spans came later: the River Orwell Bridge spans 190m, but didn't open until 1982. The 250m span Skye Bridge only opened in 1996.)

Major defects were discovered in the 1980s and 1990s (including the fact that the main span was sagging by 300mm, and one pier was tilting out of plumb). Since then, the bridge has been the recipient of a massive £30m refurbishment programme.

Only the soffit of the central span is illuminated, presumably because of the ability to reflect in the river water. For £300,000, Glasgow City Council got a system of very slowly changing coloured lights, changing steadily through green, blue, yellow, purple etc. The sequencing is supposedly linked to traffic and tide levels, but I couldn't see any particular pattern while I stood and watched.

Lighting only the underside of the bridge does well in distracting from the structure's sheer massiveness (it weighs 52,000 tonnes). I can't help thinking that £300,000 could buy a lot of low-energy lightbulbs for low-income households, however.

Further information:

Updated 7 July 2010: the post previously noted the longer span as of 1970 as being unknown, now changed as I have identified this as the Medway Bridge.

01 July 2010

Scottish Bridges: 10. Tradeston Bridge

I visited the Tradeston Bridge just over a year ago, very shortly after it opened in May 2009, and had a good look around in the day time. More recently, I returned at night.

The design, by Halcrow with Dissing + Weitling, is brutally minimalist, with an extremely slender S-curved deck achieved at the cost of heavy support pylons. There are very few bridges quite like it, although the Valencia Port Swing Bridge perhaps comes closest.

Seen previously on an overcast day, the bridge's battleship grey looked flat and leaden. At night, it looks bright white, and far more attractive.

The handrail lighting is the Rail Light system, and it seems a little overdone, judging by the amount of light spilling into the river. On the night I visited, part of one handrail light was dark, but you'll have difficulty telling where from these photographs.

There's enough light from the handrail that there's no need for feature lighting on the pylons, and these can be seen looming up into the darkness.

Since my previous visit, when climbing the pylons seemed to be all the rage, I've heard no further reports of the bridge attracting unauthorised climbers. Presumably the local CCTV is well monitored. The bridge is still seemingly well used, with quite a few people passing over while I photographed it, close to midnight.

I still very much admire its simplicity, and its starkness, which is especially the case at night. It has a great sense of presence for a bridge on a relatively small scale, and the contrasts between its angular sufaces and curved lines is surprisingly successful. Its iceberg aesthetic is at odds with the rest of Glasgow's bridges, but I like it.

Further information:

Related posts:

30 June 2010

Scottish Bridges: 9. Glasgow Bridge

Moving eastwards from the South Portland Street Bridge, the next crossing of the River Clyde in Glasgow is Glasgow Bridge.

The present structure was built in 1899 by Blyth and Westland engineers, as a wider replacement of Thomas Telford's 1836 bridge (itself a replacement for a bridge of 1772).

As masonry arch bridges go, it's not a brilliant design. The segmental arch ring seems to me to come too close to the parapet, touching the stringcourse and breaking up the spandrel wall. The result is that the arch looks flattened at its crown. It doesn't look quite right, but historic photos do seem to make clear that it's identical to Telford's original design.

The bridge piers each incorporate three secondary transverse arches, presumably to reduce loads on the foundations.

The night-time lighting is much better than at the South Portland Street Bridge. The blue intrados to the arches contrasts well with the white bridge piers and balustrades. It's a shame that one arch is unlit along with several of the piers, but that's just a lack of maintenance.

Behind this bridge, you can see the 2nd Caledonian Railway Bridge, which wasn't illuminated, so I didn't take any photos of it, nor the George the Fifth Bridge, another arched highway bridge immediately to the east (this time in concrete with faux masonry facades).

Further information:

Google maps
Wikipedia
Structurae
Clyde Bridges Heritage Trail
RCAHMS
Glasgow History (with many historic photos of the bridge)
Glasgow's Clyde Bridges [PDF] (heritage guide from the ICE)

29 June 2010

Scottish Bridges: 8. South Portland Street Suspension Bridge

It's always interesting to contrast bridges by day and by night, so I was pleased recently to make a return trip in the hours of darkness to the Tradeston Bridge, which I'd only previously seen by day. I also took the chance to have a quick look at a few other bridges along Glasgow's River Clyde.

I'll cover the bridges I looked at in order from east to west, starting with the South Portland Street Suspension Bridge.

This footbridge incorporates the oldest surviving elements of any of Glasgow's bridges across the river Clyde, with its stone towers dating from 1853. It replaced a timber bridge on the same site, which had lasted from 1833-1846. Designed by engineer George Martin with architect Alexander Kirkland, the new bridge required substantial reconstruction in 1871, leaving it essentially in its present form, although the hangers have been replaced twice more since then.

The bridge has been illuminated at night since 2005, with well over 2,000 LED lights involved. I first saw the bridge at night, and was surprised at quite how malevolently crimson it is lit, as if the bridge had not long emerged from Vulcan's furnace. You can see the twin sets of bridge chains, one above the other, and the hangers and parapets are reasonably well delineated, but the towers just look somewhat morose.

In the day time, it became clear how awkward the lighting is, totally obliterating the contrast between the stonework, the red steelwork, and the white steelwork lattice panels. It's odd, because the press release issued when the lighting was installed said that the towers would be lit in white, and more use of white light would definitely have looked much better.

Further information:

Google maps
Structurae
Clyde Bridges heritage trail
RCAHMS (many excellent photos, including one from before the latticework parapets were added)
Glasgow's Clyde Bridges [PDF] (heritage guide from the ICE)

03 January 2010

The curious case of the copycat coils

When Santiago Calatrava's Peace Bridge design was revealed last summer, it was hailed as a radical departure for the maestro of bone-white structural flamboyance: a truss, no less, and a red one at that.

Of course, its helical truss design was ambitious but by no means unique, and I've covered a couple of similar designs here before. But I had perhaps underestimated quite how many there were, so I'm taking this opportunity to put that right.

I'm not seriously suggesting that any of these designs are direct copies of any other bridge (with the obvious exception of the twin Happold bridges), but it is interesting to see just how this typology, has appeared, spread, and extended its ambition with ever greater spans.

I've put them in reverse chronological order. Click on any image for a larger version.

Peace Bridge, Calgary, Canada

Due to open late 2010. Designed by Santiago Calatrava (architect) / Stantec (structural engineer). Spans 130m. See my previous post Calatrava springs a surprise for more.

Double Helix Bridge, Singapore

Due to open 2010. Designed by Arup (structural engineer) / Cox Group (architect). Spans 65m. For more details, see Wikipedia, Bentley Generative Design article, and Singapore's URA.

Roche-sur-Yon Bridge, France

Opening February 2010. Designed by HDA Paris (architect & engineer) / Bernard Tschumi (architect). 70m long but I don't know the span. Lots of great pictures on flickr; also see Morphocode, Archdaily (especially the discussion), a photo of the previous bridge on this site, and HDA's Complexitys blog. This one deserves its own post, really, it's by far the best design of any shown here!

Harthill Footbridge, near Glasgow, UK

Opened October 2008. Designed by Buro Happold. Spans 70m. More details from when I visited it.

T. Evans Wyckoff Memorial Bridge, Seattle, USA

Opened October 2008. Designed by SRG Partnership (architect) / Magnusson Klemencic Associates (structural engineer). Spans 42m. More details at the Museum of Flight website, and at modernsteel.com [PDF].

Randstad Rail Station at Beatrixlaan, The Hague, Netherlands

Opened 2006. Designed by Zwarts and Jansma (architects). Spans 40m to 50m. More details at Archdaily.

Greenside Place Link Bridge, Edinburgh, UK

Opened 2003. Designed by Buro Happold (structural engineer) / Broadway Malyan (architect). Spans 46m. More details from my visit.

13 July 2009

Bridges news roundup

Book tells story of Forth Bridge Briggers
Eslpeth Wells interviewed on her new book “The Briggers: The Story of the Men Who Built the Forth Bridge”

City architects peddle idea for cycle way over Leith Walk
Smith Scott Mullan Associates propose new bridge in Edinburgh

Olympic footbridge touches down in Stratford
1600-tonne pedestrian bridge completes launch across rail tracks

Bridge dispute moves to court
Watson and Macalloy unable to reach agreement in £1.8m "squinty bridge" case

Roads to nowhere - abandoned, ruined and unfinished bridges
Does what it says on the tin

Spencer Dock Bridge nearly complete
Amanda Levete interviewed on Future Systems bridge in Dublin

Santiago Calatrava Wins European Steel Design Award for His Bridges at Reggio Emilia
Three bridges in Italy win ECCS prize

Pedestrian and bike bridge proposed for False Creek
Gregory Henriquez designs suspension footbridge for Vancouver

12 June 2009

Bridges dominate Prime Minister's Award shortlist

Every year, the British Prime Minister gives an award for "Better Public Building", intended to recognise not just architectural or engineering excellence, but also good procurement, positive community impact and sustainability. Of the 24 entries shortlisted this year, five are bridges, and two others have bridges as a key part of the scheme.

As this award bucks the trends of the other engineering and architectural awards schemes, it's worth seeing which five bridges have been shortlisted. They're certainly not all the usual suspects (none of the four bridges recently featured in RIBA's awards are here, for example, although one (Castleford) was shortlisted last year). Bridges often make a good showing in the Better Public Building scheme, but this looks like a vintage year.

Cathedral Green, Derby

Designed by Ramboll (formerly Whitbybird), this is a cable-stayed swing footbridge (yet to be officially named) spanning over both the River Derwent and an adjacent mill race. It swings to one side when the main river floods. It's nice to see a cable-stay bridge with so few cables, also one that is modest and simple rather than unduly flamboyant. It has been shortlisted, apparently, because "the ingenious bridge design allows rotation using minimal energy" (inherent in the swing bridge choice). No mention is made of the fact that it opened a year behind plan and well over budget.

Clackmannanshire, Kincardineshire

This one was chosen for its "construction innovation and streamlined engineering" rather than architectural flair, although the design (by Scott Wilson, Benaim and Yee Associates) is admirably done. Launched incrementally, it bypasses the existing Kincardine Bridge. Each pier is supported on a single monopile, somewhat harking back to the good old days where bridges sat on hand-dug caisson foundations. Nice to see engineering get its proper recognition.

Infinity Bridge, Stockton-on-Tees

I've covered Expedition Engineering's footbridge here extensively before, so there's not much new to say other than that I laughed at the awards website's statement that it comprises "two steel arches supporting a pre-cast concrete deck produce one of the country’s longest footbridges but – at 125mm – one of the thinnest walking surfaces." Of course, it's only 125mm thick spanning transversely, with deeper edge beams spanning longitudinally - and thinner walking surfaces exist on many steel bridge decks.

Lewisburn, Kielder

Designed by Forestry Civil Engineering, an arm of the Forestry Commission, this footbridge in the Kielder Forest must be the real wild card of the five bridges up for an award. They're no strangers to prizewinning bridges, with a BCIA award for the Salcey Forest Walkway [PDF]. It's a fairly attractive low-cost cable-stay structure, although the timber deck is somewhat let down by the fairly clumsy pylons.

M8 Harthill, near Glasgow

I've covered this footbridge before as well, having visited it earlier this year. The design by Buro Happold is one that I find problematic. The awards people seem to like its "elegance", finding it "visually striking" and with "high quality workmanship". I'd agree except about the elegance - the structural form is awkward and also far from economic. Having said that the fabrication of a complex structure like this is undeniably an impressive achievement.

29 May 2009

Tradeston Bridge opens

Earlier this month, on the 14th May, Glasgow's £7m Tradeston Bridge opened to the public. Nicknamed the "Squiggly Bridge" (in sympathy to the nearby "Squinty Bridge"), it was designed by Halcrow with Dissing + Weitling, and built by BAM Nuttall. Following a short preview back in March, the Happy Pontist has sent a special reporter all the way to Glasgow to have a proper look at the finished bridge.

The opening was as much as a year behind schedule, following difficulties with the riverside walls, disputes with the fabricator, and arguments over DDA compliance. The budget has been stated at £7m (roughly £14,000 per square metre, expensive for a landmark footbridge, albeit still only half the budget for the previous Glasgowbridge proposal on the same site).

Previously, I noted that the bridge was somewhat sober and colourless. Its stark, bloodless quality is certainly very apparent in reality, although in spite of its stiff angularity, it remains surprisingly tactile. The bridge was criticised as shortening the pedestrian route across the nearby George the Fifth Bridge by only a little, but was relatively well used while I was there, particularly given the overcast day and lack of riverside attractions. Several people were stopping not just to look at the bridge, but to touch it.

Visually, it is sharp and striking, instantly memorable and in this respect best seen from a distance. Although there’s little of note to be said about its more intimate details (the deck surfacing and parapets), closer up its visual drama and interest is enhanced. In elevation, the arrow-head supports are visually straightforward, but from almost any other angle their curves and tapering faces change constantly as you walk around and across (see picture, left). The scale of the pylons is well-balanced between the human and the inhuman.

Only the ultra-slender deck disappoints in this regard – from certain views, perspective foreshortening makes it appear as if there’s a sharp kink in the edge of what is in reality a sinuously curved deck (see picture, right).

Why is it S-curved at all? Judging from the Glasgow council’s press statements, this is to provide adequate air-draft to river vessels. If that’s right, then curving the bridge in plan gives the bridge enough length to rise up and over the navigation channel without offending disability access gradient limits. The bridge deck’s exceptional slenderness may also have been driven by this demand.

I admire its minimalism, even if it’s in danger of seemingly brutalist: my travelling companion on this trip, not a bridge designer so perhaps more representative of the fabled Joe or Jane Public, thought the bridge ugly, industrial and “a monster”.

I’m less sure how well the uniform pale grey colour will work at different times.

Most surfaces offer an attractive flatness (although not all the welds have been ground flush, so there’s still some sign of its making), but only the surfaces underneath had much in the way of reflected light and shadow. Imagine the same bridge in polished stainless steel!

The curved recesses at the foot of each arrow-head are clearly designed to discourage people, particularly on wheels, from mounting the top surface of the inclined “stay” members (for this is in some ways an unusual variant on a cable-stayed bridge). The bridge hasn’t been open long, but there is already considerable damage to the paintwork and several tyre-tread marks, suggesting that Glaswegians are more intrepid than the designers allowed for (as I predicted previously). I was certainly able to walk up the surface, and it wouldn’t be especially hard to get to the top for someone less nervous about the possible appearance of the police.

Despite its slenderness, the bridge deck was generally stable and free from wobble – but not entirely so. Even under relatively light loading, I could feel a very definite vertical vibration at midspan. Whether it’s enough for people other than nosy engineers to notice, I couldn’t tell.

It’s also too early to tell how well the bridge will fulfil its stated aspiration, which is to act as a focus for regeneration investment on the south bank of the Clyde, and establish a high-quality riverside appropriate to the high-value businesses sought on the north bank. It’s not the best stage in the economic cycle to judge how well it will succeed in this aim.

Overall? I do like its simplicity, its flat yet sculpted quality, and the way its curvature generates visual variety out of such limited means. I’m nervous about its susceptibility to trespass and graffiti, and hope it doesn’t have to be disfigured to discourage climbing (a risk that could have been minimised by adopting diamond-shaped rather than rectangular section “stays”). It’s good to see that there are still new tricks to be played with the established repertoire of bridge forms. And after the fiasco of the previous bridge design competition on this site, I’m just glad a landmark bridge did finally get built here. It may lack the showmanship of the original competition designs, but as is always said about minimalism, sometimes less can be more.

02 May 2009

Forthside Bridge opens

The £6.5m Forthside Footbridge in Stirling, Scotland, has opened today, some twelve months behind schedule.

The footbridge (pictured right) crosses Stirling Railway Station, and provides access between the new Forthside development and the town centre.

Designed by Wilkinson Eyre and Gifford, and built by Edmund Nuttall, the new bridge comprises two 88m span inverted Fink trusses, in an unusual arrangement that makes the bridge significantly different to the only other major bridge of the same form, the Royal Victoria Dock footbridge, not to mention unbuilt designs such as Flint and Neill / Exploration Architecture's Perpignan Bridge (shown below in colour) or Mott MacDonald / Knight Architects' River Douglas Bridge (shown below in black-and-white).

The trusses are assymetrical, being higher at one end than at the other, and each truss decreases in height in the opposite direction (see extract from planning drawing on the right), such that the bridge deck is supported on each edge by a propped cantilever - but with the cantilevers in opposing directions such that there is presumably a marked tendency in the deck to twist (dealt with structurally by making the deck a flattened box girder). The inverted Fink truss is inherently inefficient, and the assymetric arrangement will have added to that, as does the fact that the trusses aren't in a vertical plane, but incline outwards from the deck at an angle which warps along the deck by 35°.

All this adds up to a bridge which is exceptionally complicated geometrically. The justification for this comes from the wish to cradle the walkway in a manner which visually echoes the pedestrian desire lines (which are at an angle to the bridge span). From the photos and images currently available, I think it's an exciting design, taking a simple structural idea and playing with it in a very interesting way. It's especially nice to see such an innovative bridge resulting from the much-maligned Design-and-Build approach, often seen as a source of poor design quality.

The bridge is 113m long overall, so for those who pay attention to such things that's a cost of £57,500 per metre length. Assuming the bridge to be typically about 4m wide (actually it varies, but the clear useable width at midspan is certainly less than 4m - see planning drawings), that's a cost of over £14,000 per square metre of deck. This is high even by the usual standards of landmark bridges (a range of £4,000 to £7,000 per square metre was about right just a couple of years ago), so Stirling Council could have had an attractive, albeit less remarkable, structure for far less.

The delays completing the bridge have been attributed by Nuttall to the complex stressing sequence required, as well as the need to verify cable connectors supplied without proper testing. The difficulties of building such a highly assymetrical structure were alluded to in a technical paper by the designers [PDF].

Overall, it's one of my favourite Wilkinson Eyre designs of recent times, and likely to be a strong contender for various design awards over the next year or two.

Updated 4 May 2009: added credit to Explorations Architecture for Perpignan Bridge, and higher-resolution image

27 April 2009

Scottish Bridges: 4. Harthill Footbridge

After seeing three historic bridges in Scotland, it was time to finish off with something much more modern. So modern, in fact, that it hasn't yet reached its first birthday.

I posted about the £5m Harthill Footbridge when it was installed in October 2008. It spans 70m across the M8 Motorway, connecting the eastbound and westbound service stations at Harthill. It was designed by Buro Happold, adopting the same unusual helical form they had previously applied to Edinburgh's Greenside Place footbridge.

At Greenside Place the complex steel truss had (some) justification, as the bridge is S-shaped on plan and the helical truss is to some extent an efficient way of resisting the resulting torsion.

Nonetheless, it's a very expensive solution, as the cost of bending and welding together all the tubular elements must be well in excess of what is involved in a more conventional truss or box-girder solution. It also leads to a substantial amount of understressed metalwork, as the same cross-section appears visually to be applied throughout, although the various load effects in the bridge will vary considerably.

At Harthill Services station, these issues become more prominent, as the bridge is straight in plan and hence torsion is greatly reduced. The bridge's aesthetics also become far more problematic - a bridge looking like a tube can look okay when spanning between the vertical facades of buildings (see also Manchester's Corporation Street footbridge for an example). When sat with its ends in mid-air, it looks awkward.

The end termination problem is exacerbated by the very short cantilever end spans (I believe the spans are 10m, 70m, 10m) and the very differently styled approach ramps, which are there to provide disability access without the maintenance liability required by a lift. Personally, I think lift towers at either end would have looked far better. The new staircases are also somewhat cheap-looking compared to the rest of the bridge.

Of course, many of these issues are likely to be the result of choices outside the designer's control. The approach walkways, staircases and span arrangements will all be constrained both by the limitations of the site and of the client's budget. An attempt has been made to use interesting "trussed" parapets on the approach ramps to echo the diagonals of the main span elevation, but it just begs the question of why the main span isn't also a more straightforward Warren truss. Indeed, why is it covered at all, when there is a lengthy uncovered approach at either end?

The bridge is not without its attractions. The helical truss allows the main structure to be divorced from the glazed walkway enclosure, acting as a skeletal cradle, with an interesting visual rhythm (it will also make the outside of the glass a bugger to access for cleaning). It's also undoubtedly nice to see a major UK highways client investing in something aesthetically different and avoiding the identikit bridges which litter British motorways.

But for me, this was an interesting bridge to stop and see, but not one to love.

Further information:

The Happy Pontist