Commuters are being warned to expect “major impacts” to South West Trains services as Waterloo station undergoes an £800m upgrade.

Network Rail and South West Trains have launched a campaign advising commuters about the changes, which will come into effect in August next year while the central London station is redeveloped.

The engineering works will require platforms one to nine to be closed between Saturday, August 5 to Monday, August 28.

Stuart Kistruck, route managing director at Network Rail, said, “Work to deliver our railway upgrade plan at Waterloo is progressing at a fantastic rate and this will continue behind the scenes.

“As there will be major impacts on services, we want everyone to have plenty of time to plan ahead while we invest for better journeys down the line.”

According to Network Rail, the number of journeys on lines into Waterloo have more than doubled from 108 million 234 million in 20 years.

The station upgrade will allow services to provide more seats on longer trains by lengthening certain platforms at a cost of about £800m.

Five disused platforms will come back into use and platforms one to four redeveloped to accommodate 10-car trains.

Christian Roth, managing director at South West Trains, said: “The Waterloo and South West Upgrade is the biggest investment in this railway for decades and will provide more trains, more seats and more space for tens of thousands of passengers every day.

“We are doing everything we can to minimise the impact on passengers while the work is carried out but there will be some changes to services next summer.”