Bridges news roundup

'World's longest' composite bridge debuts in Madrid
44m long carbon-fibre reinforced plastic u-frame footbridge took 30 days to prepare and 2 hours for constructor Acciona to install.

Architectural secrets of Houston's newest landmark — the Rosemont Bridge, revealed
An interview with Julia Mandell of SWA Group regarding a new US$5m footbridge. The treatment of the balustrading wrapped around the trusses is nice, drawing on their experience from their previous footbridge near Houston's Hobby Center.

Dallas City Council approves cheaper alternative for McDermott Bridge over the Trinity River
It's hard to know where to start with this story. It was to be the second of three Santiago Calatrava-designed bridges in Dallas (the first is the US$93m Margaret Hunt Hill Bridge, spanning 365m, and due to be completed later this year). The Margaret McDermott Bridge was planned as a 610m long bridge with a 305m main span, with a road deck slung below a quartet of arches, the tallest of which would rise 76m. Cost estimates for this spectacular design varied between US$314m to US$500m, and despite securing some US$92m of external funding for the project, the state of Texas has found the bill to be simply too high.

Having ditched the Calatrava arches, they are reportedly going for a less extravagant US$220m project, which still seems grossly inflated for a bridge of this size. What's particularly striking, however, is the news that they want to retain Calatrava to design only the bicycle and pedestrian elements of the cut-price design, and will be paying him some US$10.7m to do so - US$2.1m left over from his incomplete arch bridge contract, US$3.5m of Dallas funds, and an amazing US$5m of donations from an anonymous philanthropist.

There is clearly an argument that it's worth paying over the odds for the prestige of a brand name designer, but with the iconic element of the bridge gone, it's hard to credit why anyone would pay so much money simply to design its footways.

Million pound bombshell could wreck Perth bridge plan
This project for a Sustrans-supported cycle bridge near Perth had already been struggling with land purchase issues, but having seemingly resolved those, it has now been hit by the design consultant's announcement that it may cost £1m more than expected - extra money that simply isn't in the budget. Indeed, it's not even that simple. An original estimate of £1.8m for construction costs was apparently based on a simple "per square metre" figure. However, according to the Perthshire Advertiser, an additional £755k for craneage costs was later added, with the capital cost rising first to £3.5m and then eventually to £5.25m.

The bridge design consists of three arch spans, 200m long in total, supporting a 3m wide deck. So, for the original £1.8m estimate, that works out at £3,000 per square metre, which is cheap for a landmark bridge, but certainly achievable for a footbridge with no unusual construction issues. The latest £5.25m estimate would work out at £8,750 per square metre, which is expensive for the relatively straightforward structural form, but not unreasonable given the difficult access for construction in a wide river.

What will happen next is unclear - I would guess the scheme will be dropped completely, although the simple exercise of inviting preliminary tenders or getting an ECI contractor on board might help increase cost certainty.

Renowned Architect Designs a New Pedestrian Bridge for Revere Beach
Rosales & Partners propose a cable-stayed footbridge which is simple and elegant.