The Subway at Glasgow will be shut for a fortnight longer than expected after modernisation works have been hit by delays.
The underground service shut at the beginning of July to enable engineers access to the tunnels as part of a £288m modernisation programme.
Strathclyde Partnership for Transport (SPT) initially said the works were expected to be completed by the end of the month but on Thursday announced the “regrettable” delay.
A spokeswoman said contractors Colas Rail estimate the reopening date will now be “around two weeks” after August 1.
She said removing concrete from the tunnels was taking longer than expected, while heavy rainfall had caused flooding that further delayed the works.
Eric Stewart, SPT’s assistant chief executive, said: “This is the most significant engineering aspect of the whole modernisation programme which is being built to last for another 40 years.
“This is a regrettable position and we are working with the contractor to pull back some of this lost time, as we endeavour to minimise any further disruption to our passengers.
“We apologise to all our passengers for this inconvenience.”
While the works are ongoing a replacement bus service is running along the underground route.
The service includes additional direct services to the city centre from key stations such as Bridge Street, Kelvinbridge and Shields Road.
Fares are £1 for a single journey, £2 for a return and £2.50 for an all-day ticket. Child fares are 50p single and £1 return.
Services run every five minutes at peak times and every ten minutes during off-peak.