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Outward Bound

Long before the Thameslink programme is complete passengers will start to benefit from longer trains, which requires a major programme of platform extensions at outlying stations.

While the more glamorous Thameslink projects at Blackfriars, Farringdon and London Bridge get most of the attention, the main concern for many commuters north of London is simply getting a seat on a train.

Platforms at so-called “outer” stations, like St Albans, Luton and West Hampstead, are only long enough for a maximum train length of eight cars, so passengers are often squeezed onto trains at peak times.

Now, as part of the £5.5bn Thameslink programme, platforms are being extended at key outer stations so they will be long enough for 12-car trains to stop.

Thameslink programme manager Damien Gent says: “The vast majority of this work isn’t particularly glamorous or sexy, but it is essential to give passengers north of St Pancras more capacity. Thameslink has had a huge amount of passenger growth,” he adds.

“Communities south of the river have always had other alternatives because of the number of different rail routes, but north of the river they didn’t really have anywhere else to go.”

While 12-car trains can already run on the southern section of the Thameslink network, this has not been possible north of the Thames because of the shorter platform lengths. Platforms have not previously been extended because of the scale of money, time and effort required.

Building a new route from Elstree

Building a new route from Elstree

Now, with improvements being made to increase capacity elsewhere on the network − particularly at London Bridge − platform extension becomes viable as part of the larger project. To fit the longer trains in, platforms must be extended by up to 80m, with a total of almost 4km going in at stations from West Hampstead to Bedford.

This is far from simple, as almost every station has bridges, gantries, overhead lines or signals that are in the way of the new platforms. “I would love there to be a standard format for these platforms, but actually it is completely driven by the constraints of each site,” explains Gent. “Our focus is on releasing the constraints so that we can get on with building those platforms.”

The first platform extension to by completed, in December 2008, was Luton Airport Parkway. This was fairly straightforward, as the station was only built 10 years ago, and, although the platforms were constructed for eight-car trains, the rail systems were in the right place for longer trains, so it was just a case of extending the four platforms by 80m.

Since then, work has been somewhat trickier, and it all has to be done during rail possessions. “It has always been one of our key drivers to minimise impact on the travelling public, and, where possible, we’ve worked at evenings and weekends so there’s no disruption in the busiest times of the week,” explains Gent. “One of biggest issues is phasing the work,” he adds.

“We couldn’t do all 12 stations in parallel, so we’ve sequenced them out to build two or three per year. We’ve just come off the peak of that workload, and we’re over half way through.”

Work on the Luton bridge

Work on the Luton bridge

According to Gent the biggest challenge so far has been extending the platforms at the station in the centre of Luton. The main constraint was a bridge at the north end of the station that acted as a pinch point for the tracks, giving no width for the extended platforms. The only way around this was to widen the bridge.

Last Easter the team had a four-day track possession, took out three existing bridge decks and replaced them with realigned new deck. This provided additional width to allow the platform extensions to be constructed.
Throughout the work, the adjacent Midland Main Line fast tracks kept running.

Preparation for that weekend began in November 2009 with work to build new abutments and strengthen sections of the existing structure. Then, in the New Year, fabrication of the new steel decks began. At that stage the team − including Network Rail, main contractor Carillion and various specialist subcontractors − started building up an hour-by-hour plan for the weekend’s activities.

The new bridge decks were delivered to site three weeks before Easter, when the team started having what Gent describes as “significant” integration workshops to talk through the plans, sequencing, plant, materials, labour patterns and shifts for the weekend possession.

When the time came, the old decks were cut away and lifted out, and the new, wider, structure − weighing 160t − was rolled into place using special transporters designed for heavy loads. Overhead wires also had to be moved, and the new track, laid before the line could reopen.

Throughout the weekend more than 250 people were on site, with shifts covering 24-hour working. Gent has nothing but praise for the exercise. “It is complex weekends like this that really test the professionalism of the industry,” he says.

“There is no point in making the effort in the centre of London if trains can’t actually stop at the critical outer stations because they’re too long”

Damien Gent, Network Rail

Much of the focus now is at West Hampstead, where a new footbridge has already been constructed to give step-free access to all platforms, and a new station building is planned on an adjacent road. “This is an area where we are anticipating many more passengers once the work is completed,” explains Gent.

The station gives passengers access to the Tube network, but at the moment that requires some tricky road crossing, which will be reduced when the new station opens, making it a more attractive proposition for commuters.

Again the work is far from straightforward. The project involves building a major embankment for the new station, while the new footbridge had to be lifted in using a 500t crane, which needed significant temporary works − including a sheet piled wall − to create a stable platform on which it could be set up.

Not all of the outer stations are having their platforms extended. For example, Kentish Town has road bridges at each end which cannot be moved, so there just isn’t space to fit them in.

Meanwhile passenger numbers at Cricklewood and Hendon are not high enough to warrant 12-car trains calling there, so platforms will not be extended either. Shorter trains will continue to run throughout the day so that these stations will not lose out.

Outworks diagram

Work on the outer stations is on schedule for 12-car trains to start running right through the network from December 2011. Gent says the success of the project so far is due in part to the strength of the people around him. “I’ve built a very specific project team of 28 people to deliver these stations,” he says.

“It’s a dynamic, multidisciplinary, integrated team. We’ve co-located with a number of our contractors to create a collaborative approach to design and programme development.”

Gent was attracted to the role because he says the project will deliver “real, tangible benefits”. “What’s absolutely key is finding like-minded people who are passionate and committed,” he says. “You can take a complex footbridge from design to installation in 120 days if you have that. “It’s an amazing team,” he adds.

“We all took the attitude that we’ve got 12 of these stations to do by 2011, so we’d better get on with it. There are people from the team with all sorts of backgrounds, because project delivery is a portable skill. But if you take those skills and link them up with the engineering skills, then you’ve got a successful mix of people.”

Power hungry

It is not just longer platforms that are needed to run longer trains more frequently. Often invisible to rail users is the essential work to bolster power supplies and improve signalling capacity.

These improvements include a new auto-transformer system and a 400kV supply from the Elstree Grid. Between Farringdon and City Thameslink, the overhead lines have been extended, and there have been upgrades to the third-rail DC system south of the river Thames.

At the same time, improvements are being made to the West Hampstead and Victoria signalling centres to increase capacity and reliability in advance of the timetabling change.

 

Thameslink’s key suppliers

Balfour Beatty
Costain
Skanska Construction UK
Invensys Rail
EDF Energy Contracting
Jacobs Engineering UK
Atkins
Malla Rail
Giffen Group
Carillion Construction
Telent Technology Services
Tony Gee & Partners

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