London Transport Museum: Full steam ahead (Project report)

The London Transport Museum is getting a £19m makeover. Wates has the job of refurbishing the building - but first it had to move out the exhibits. Will Mann reports.

You wouldn’t normally expect to see Wates carting a tram through the streets of London. But then, this isn’t a normal job.

The contractor has been working on the £19m refurbishment of the London Transport Museum (LTM) in Covent Garden. Aside from the complexities of restoring the 19th century Grade II-listed building, and adding several new features, Wates has also had to organise the logistics of moving exhibits out of the museum and into storage at the museum depot in Acton.

Evacuation of the exhibits started in March 2005, although the bulkier objects were not moved out until after the museum’s closure in September 2005. Some 400 exhibits were taken to Acton, with only a handful remaining on the mezzanine floor for logistical reasons. These locomotives, carriages and trams were packed inside protective MDF casing, although their wheels are just visible, providing the only clue to the building’s purpose during the construction programme.

The contract is two-stage, with the subcontractor packages split into a mixture of contractor design or consultant design depending on the complexity of the work. This has also resulted in some design changes during the programme, although “nothing that has altered the overall design scheme in a major way”, says museum project director Belinda Betts.

Demolition phase
Before the business of restoring the main building could commence, there was a short demolition phase, carried out by Greater London Demolition, which involved ‘carcassing’ the interior, stripping it back to the basic structure.

There were also substantial excavation works, for the museum’s new theatre, which meant digging 10m below ground level. Given the history of the area, a team from AOC Archaeologists were brought in at this point, finding, among other things, a skeleton believed to date from the 9th century.

This phase of the project also involved construction of new reinforced concrete foundations to support the new steel-framed structure Wates is building inside the museum. It finished in March 2006.

In the main building, repairs to the roof are the LTM’s biggest priority. The museum occupies a Victorian flower market, and was built for market traders rather than antique trams and tubes. It features a 1.5m-high upstand in a lantern-style design, with vertical clerestory glazing.

Period design
The period design is an integral feature of the building, but meant that light levels inside were far too strong for the safe display of old posters and maps. It also caused wild swings in temperature: during winter, temperatures would drop to near zero, while in summer they could soar to over 40°C, causing condensation problems – there was even an internal gutter inside the roof to catch water droplets.

This existing structure, around 18m high at its apex, had to be retained and refurbished, including the roof lights. So a solid zinc roof is being constructed to sit over the top.

“This new roof structure will rest on the museum building’s existing wrought iron frame,” explains Wates project manager Alf Stephenson, “and because of the loading pressures, it has been constructed out of aluminium.”

As might be expected, access for the roof works has been tricky. The LTM is hemmed in by busy streets on three sides, and the piazza on the fourth. Wates’ solution was a modular system, which meant constructing the roof one section at a time.

First, an 8m2 assembly platform supported by scaffolding was built on the western side, alongside three hoists. “We would normally have used just one, but the tight timeframe meant we opted for three,” explains Stephenson.

After being lifted up to the roof level, each section was then slid along the aluminium section on rails working backwards from the east. “Where there was a cross section of the roof, we had to bring in a mobile crane to lift in these sections,” says Stephenson. The remaining sections were installed using a light scaffold structure, which sat on the roof.

The new vertical roof lights comprise double glazing incorporating sun shading – a geotextile wool that sits between the glass panes. Aluminium louvres along the side of the upstand section will provide solar shading for the clerestory windows.

When complete, the roof will cover an area of approximately 3,000m2 on two levels, and includes 1,000 photovoltaic panels. Part-funded by the Department of Trade & Industry’s Photovoltaic Demonstration Programme and Transport for London, they will generate about 16% of the museum’s peak electricity needs during summer.

The remainder of the roof is slated. “It’s proved very complex interfacing the slates and the PV panels,” says Stephenson. “There’s a difference in level of 50mm to 60mm where they abut, so the lead flashing has to be spot on to ensure the roof remains watertight. Just in case, we’ve also constructed a ‘secret gutter’ underneath to collect any rainwater that gets through.”

The PV panels are connected directly to the plant room that sits above the roof of the office area on the southern (Tavistock Street) side of the LTM. “The current from the panels is DC, so an invertor has been fitted which converts it into AC,” explains Stephenson.

Offsite assembly
The plant room weighs some 25t and the steel frame it sits on is another 25t. “It was assembled offsite in two halves, lifted up using a mobile crane and bolted together,” says Stephenson. “The loads come down through the office structure.”

The plant will support the new heating and ventilating system, which should provide better regulation of internal temperatures.

Inside the museum, the principal new feature is an extra floor above the mezzanine, which is being supported by a new steel structure. Most of this bears down on the existing foundations, although these have been strengthened with reinforced concrete. Three lifts are also being added.

The structure abuts the original wrought iron frame, although it will be painted and clad to be sympathetic to the original structure, says Stephenson. “The structure itself required some strengthening, but was otherwise in good condition.”

The location of the LTM has understandably meant some working constraints for Wates. Besides the expected dust controls, the proximity to other neighbours – notably a theatre museum underneath the LTM, which was a particular issue during the theatre excavations – has also placed restrictions on working time. Wates could only carry out noisy work for two hours each day during the week except for Monday.

The museum’s reopening was originally planned for next summer, although the design changes have meant a slight delay. “We’re as confident as we can be that we’ll be opening in the autumn,” says Betts.

The revamped LTM will reflect TfL’s wider remit, and feature exhibitions that include cycling, taxis and the river, besides the usual trams, trains and buses. There will also be a two-storey shop, café-bar overlooking a gallery, plus the 120-seat theatre.

Bringing back the exhibits and setting them up is not part of Wates’ deal, although the contractor is optimistic of picking it up as an add-on. So if you see a tube train on the back of a Wates lorry next autumn, you’ll know why.

[Contract Journal, 8 November 2006, p 21-22]