The boss of Network Rail has apologised to passengers as a signalling problem caused fresh delays at the UK’s busiest railway station, on the first day after long-running engineering works were completed.

Its chief executive, Mark Carne, said London Waterloo had fully reopened “a little bit later than planned”, with testing keeping some platforms closed during the early morning rush-hour on Tuesday, when commuter numbers were expected to be higher after summer breaks and the August bank holiday weekend.



The knock-on effects of the closure disrupted South Western trains throughout the morning. A spokesman said normal service would be resumed in and out of Waterloo by 2pm.

The hitch marred the successful delivery of one of the most prominent rail engineering projects in recent years. Speaking from Waterloo in a video message, Carne said the “amazing” project to increase capacity by 30% would make a “huge difference” in the long run.

Passengers voiced their anger at the delays, with some asking how Carne had managed to get to Waterloo to deliver his message. Early services were delayed or cancelled and some stations along the South Western route, including Queenstown Road, Earlsfield and Norbiton, were closed, frustrating commuters who have endured a month of disruption during the transport hub’s £800m overhaul.

Network Rail said Waterloo was fully reopened at 6.50am on Tuesday after one of the “largest and most complex” upgrades in the station’s history.

A statement said: “However, due to safety-critical work to test the signalling taking slightly longer than planned early this morning, we are expecting disruption to the morning rush-hour. Network Rail apologises to passengers for any delays to their journey and asks them to check before they travel this morning.”



A 1,000-strong team of engineers and trackside staff have been working 24 hours a day for the past three and a half weeks to complete the work.



The work was part of the £800m Waterloo and South West upgrade intended to boost capacity at the station by 30% by December 2018, providing space for a further 45,000 passengers at morning and evening peaks.



Becky Lumlock, route managing director at Network Rail, said: “The work we have completed in three and a half weeks this August will benefit passengers for decades to come. The longer platforms will create space for longer trains, making journeys more comfortable for passengers, particularly at the busiest times of day.”



Work will continue at Waterloo for another 16 months, as Network Rail redevelops the former Eurostar terminal to provide another five platforms for permanent use by the end of 2018.

Network Rail listed 180,000 hours worked, 1,389 yards (1,270 metres) of track laid, 252 yards of pre-cast concrete installed, 175 yards of new platform built and seven miles (11.3km) of cable laid over the past three and a half weeks.



Andy Mellors, the managing director of South Western Railway, said: “I’d like to thank our passengers for their patience over the past few weeks. It’s clearly been a challenging time but these improvement works will help us deliver the increased capacity needed for the future.



“As well as Network Rail’s orange army who completed the works, I’d also like to thank South Western Railway colleagues and those working for other industry partners for their hard work over many weeks in preparing for this incredibly complex infrastructure upgrade, as well as providing assistance to our passengers during the works.”



The Waterloo works coincided with one of Network Rail’s busiest bank holiday engineering programmes in the capital, with stations including Euston and most of London Bridge out of action at the weekend for upgrade work.

The Rail, Maritime and Transport (RMT) union paid tribute to its members who had worked on the Waterloo upgrade but warned that the beneficiaries would be the new private operators of the South Western franchise – a consortium of First Group and Hong Kong-based MTR.



The RMT general secretary, Mick Cash, said: “RMT’s engineering members have worked flat out against the clock in an effort to hit punishing schedules to deliver the wholesale remodelling of Waterloo on time. It was always going to be a massive challenge and the men and women who have battled against the odds at the sharp end deserve nothing but praise.”



“The financial beneficiaries of all this effort and public investment are the new Chinese owners of South Western Trains, who will be able to cream off even fatter profits from longer and more frequent services without stumping up a penny piece for the new infrastructure costs.”

The union is seeking assurances about the role of guards as the company overhauls its train fleet, threatening an industrial row ahead of the kind seen on Southern rail in the last year.



Cash said it was “scandalous” that First MTR had not pledged to retain guards, adding: “This company are benefiting big time from the British taxpayer and they should be forced to give a guarantee on safety and access and that means honouring the long-standing agreement with RMT to retain the guard on South Western Trains.”



