THE amount being invested in railway improvements over the August bank holiday weekend will be the biggest yet at this time of year said Network Rail, as plans for work costing £133 million were being finalised. As well as many projects affecting existing lines, they also include early enabling works for HS2.

Several routes into London are featured in the plans, including the Great Western and West Coast main lines. London Waterloo station is being enlarged during a major blockade between 5 and 28 August, work on Crossrail will continue and the Thameslink Programme will also make further progress.

Network Rail pointed out that rail links to airports will not be affected, over what is traditionally a very busy bank holiday for air traffic. Unusually, a new franchise will be launched on the Waterloo routes on 20 August while the blockade is in progress, but plans have been made for a seamless transition from Stagecoach to a joint venture of FirstGroup and MTR, which won the South Western franchise earlier this year.

Network Rail chief executive Mark Carne said: “This August, thousands of rail workers will be working round the clock to deliver essential upgrades to the rail network. We will see major milestones met on crucial London infrastructure projects including Crossrail, Thameslink and the Waterloo and South West Upgrade.

“Reaching these major milestones means that passengers will be one step closer to experiencing real benefits by the end of this year with more to come in 2018/19, including more than 170,000 new seats for the daily commute into London – a 20 per cent increase  – as new fleets of trains, running on new and upgraded infrastructure, are introduced.

“These huge investment projects now need several uninterrupted days to complete critical work. We know there is never a good time to disrupt services to get this work done, but it does make sense to do so when fewer people are travelling. Bank holidays and the summer months can see up to 50 percent fewer passengers using the railway.

“This vital investment will make the railway more reliable for years to come, while improving journeys for thousands of passengers. There will be major changes to services throughout August and the bank holiday weekend, so we strongly advise passengers to plan their journeys as early as possible.”

The most noticeable changes will affect London Bridge, London Euston, London Waterloo, London Liverpool Street and London Paddington. 

The Waterloo blockade will reach its peak over the weekend, when Platforms 1 to 14 will be closed. However the former international platforms, 20 to 24, will be brought into use as partial substitutes. There will be no Southeastern services at London Bridge, Waterloo East or Charing Cross between 26 August and 2 September, and the routes between London Liverpool Street, Shenfield, Ingatestone, Billericay and Barking will be closed on 27 and 28 August.

Southeastern train services director Ellie Burrows said: "The closures mean we are unable to run our normal service and it will mean considerable disruption for our passengers, particularly for those four working days. We are doing everything we can to provide alternative journey options, and we'll be running longer trains where possible. But with the three major London stations closed there will be fewer services, queues are to be expected and trains that do run will be very busy.”

Great Western services will be affected by work between Swindon and Bristol Parkway from 19 August until 15 September, and London Euston services will be suspended on 26 and 27 August so that a new power supply can be installed. HS2 enabling work is also starting at Euston.

Network Rail warned that although London Marylebone, Kings Cross, St Pancras International and Victoria are not directly affected by the engineering work, these stations are all likely to be busier than usual.