Passengers were queuing for buses again on Wednesday

Buses have been replacing trains because engineering work over the Easter weekend, expected to finish on Monday, is taking longer than expected.

A rail watchdog said many travellers would be disappointed by the delays.

Network Rail apologised for the disruption and said hundreds of engineers were working round the clock.

The line between Swansea and Cardiff was closed last Friday for work on the Port Talbot East signalling project, a 22-mile stretch of line running from Llantrisant to Baglan.

I have heard there are a lot of people who are annoyed and have been getting agitated Philip Adey, passenger

The work is part of an ongoing �400m investment by Network Rail on the rail system in south Wales.

On Monday it was announced that delays in the commissioning and testing meant that buses would still replace trains on Tuesday.

On Wednesday morning both Arriva Trains Wales and First Great Western, who have issued an apology to passengers, confirmed the arrangement would stay in place for another day.

All Arriva Trains Wales services running between Swansea, Bridgend and Cardiff are currently being replaced by bus services.

Long distance, First Great Western high speed services are starting and terminating at Cardiff Central station, with replacement bus services running between Cardiff Central, Bridgend, Port Talbot Parkway, and Neath.

We will undertake a full investigation into the causes of this overrun once normal services have been restored Robbie Burns, Network Rail

The replacement bus service between Cardiff and Swansea is extending journey times by up to an hour.

Passenger Phillip Adey said the disruption meant he had been late getting to work.

He said: "It is a bit of a nuisance, because there are too many regular ones (buses) to Cardiff, and as I said, not enough to get you into Neath to get to work on time, so it is a bit of a nightmare.

The work is taking longer than anticipated

"I have heard there are a lot of people who are annoyed and have been getting agitated and shouting at other people because they've got trains to catch in other directions."

Later on Wednesday, Network Rail announced the stretch would remain closed until the weekend.

Robbie Burns, western route director for Network Rail, which owns and operates the rail infrastructure, said: "We can assure passengers that we have hundreds of engineers working around the clock to finish this crucial work.

Many passengers will have planned around the original timescales of the disruption to services and will be disappointed Spokeswoman, Passenger Focus

"We share the disappointment of passengers in south Wales and thank them for their continued patience.

"We will undertake a full investigation into the causes of this overrun once normal services have been restored - that has to be our priority for now."

Passengers are being advised to visit the national rail enquiries website or call their inquiries number to find out the amended timetable.

A spokeswoman for the watchdog Passenger Focus said timescales for engineering work should be honoured.

Ageing infrastructure

"While passengers accept the need for engineering works and look forward to seeing the improvements they will bring, many passengers will have planned around the original timescales of the disruption to services and will be disappointed to find that the line hasn't reopened when promised," she said.

Martin Evans, chair of the Chartered Institute of Logistics and Transport Cymru, said engineering works, and in particular work on signalling, did tend to overrun.

Mr Evans said the current work was about making sure there were no delays in the future from an ageing infrastructure.

"This is a �400m project to resignal south Wales, so this is basically repair and renewal. It's work that would be undertaken probably only every 30 years or so."