Disruption to services in and out of London Paddington is likely to persist after an incident during the testing of a new intercity train led to the closure of tracks for almost 14 hours at one of Britain’s busiest rail stations.

Train operators and Network Rail said passengers still faced significant disruption, although two of the four affected tracks reopened at midday. Limited services were running west from the capital on Wednesday evening but tracks were to close from 9.15pm to allow for full emergency repairs. The knock-on effects were expected to affect Thursday morning services.

Trains had been unable to run between Paddington and Slough or Heathrow during the peak morning commute on Wednesday because of severe damage to overhead cables near Ealing Broadway in west London. The loss of power also stranded a number of trains between Paddington and Reading.

Great Western Railway (GWR) advised customers to travel only if necessary on Wednesday afternoon and to check for updates before leaving home. GWR tickets were being accepted on other train services to London’s Marylebone, Euston and Waterloo stations. The operator said tickets for Wednesday’s services would remain valid on Thursday should customers choose to postpone, and full refunds would be given for those who chose not to travel.

Twitter users expressed both dismay and amusement.

@GWRHelp thank you for the rail replacement bus service this morning aboard a 1960’s routemaster from Southall to Paddington :)



A surprise of nostalgia is very welcomed and totally unexpected.#rememberthepostiveofGWR @GetWestLondon @NetworkRailPAD @BBCTravelAlert pic.twitter.com/zmpiLgDAnw — Freshie Desi (@FreshieDesi) October 17, 2018

The damage was caused by the pantograph on a Hitachi train ripping down about 500 metres of power lines during a test run from London to Bristol at around 10pm on Tuesday. Hitachi said 12 of the same Class 802 trains, which run on diesel and electric and are part of the £5.7bn intercity express programme (IEP) ordered by the government, were already in operation on the line.

A spokesman said the train had now been returned to the depot for examination. Hitachi’s IEP trains have had teething problems, including the breakdown of a train with ministers on board during the official launch a year ago. The cause is yet to be established. Most of the Great Western mainline has been electrified in a partially abandoned upgrade marked by blown budgets and delays.

Network Rail said of Tuesday night’s incident: “Extensive damage to 500 metres of overhead electric power lines last night stopped trains running between London Paddington and Reading and Heathrow this morning.

“We have been working all day on our plan to replace the electric lines and associated equipment quickly and safely. We have been doing as much as possible away from the track, but we can only carry out repairs in earnest when trains are not running.”

A spokesperson said the track would close between 9.15pm and 5am on Thursday for the installation of new wires. “The extent of the damage means we will not be able to complete our repairs in one night, so while services on Thursday morning will be significantly improved, there may still be some disruption. We advise passengers to continue to check with train operators before travelling.”

The track closure also affected some other services. South Western Railway told customers its trains into London would be busier than usual. Southern, Southeastern, Thameslink and Gatwick Express reported cancellations and delays of up to 45 minutes.