TRAM bosses have been forced to apologise after commuters were left stranded by an early morning gridlock which saw buses log-jammed across the city centre.
Major tailbacks were caused yesterday by work to restore traffic management measures in the West End to how they were before the tram works.
Problems with the sequencing of traffic lights saw some buses delayed by up to 50 minutes, with passengers forced to get out and walk.
Tram firm TIE today apologised to travellers caught up in the disruption, promising that there would be no repeat of the problems.
However, there was anger from commuters, with some complaining that they had been forced to walk from Haymarket to Waverley station due to the length of the tailbacks.
One traveller, who did not want to be named, said: "Some of the bus drivers were letting people off half way along Shandwick Place because they couldn't get near Princes Street.
"There were some anxious-looking tourists forced to pull their luggage along the street towards Waverley because it was going to take the bus forever to get there."
Iain Coupar, marketing director for Lothian Buses, said some of the firm's buses had been delayed by up to 50 minutes, with tailbacks stretching on for most of the day.
He said: "There was a reinstatement of the West End, putting it back to the way it was before the tram works.
"What seems to have gone wrong is some of the traffic light sequencing..
"We don't really know what happened, but the council are in trying to sort it out."
It is not the first time that traffic management changes carried out by TIE have brought the city to a standstill.
The tram firm and council were forced to apologise following the botched closure of The Mound in October 2008, which left the city centre gridlocked.
A spokesman for TIE said: "Some congestion was caused as work began to reinstate the West End junction.
"Planned traffic management did not work and we apologise for any inconvenience. Steps have been taken to resolve the situation, including deploying police traffic wardens.
"Work will continue in this area through next week but should not cause further undue disruption."
The traffic changes are being made due to an ongoing dispute with contractor Bilfinger Berger, which has seen work in the West End grind to a halt.
Shandwick Place was expected to close to traffic for 18 months earlier in the year to allow for tram tracks to be installed, but there is still no sign of the working taking place.
Transport bosses intend to close the street to cars for good once the trams are up and running.