Around 40% of Dublin Bus routes may have to be taken out of College Green because of "citywide congestion" since the introduction of Luas Cross City, according to Dublin City Council officials.

Director of Traffic Brendan O'Brien said the National Transport Authority is assessing further restrictions on buses or taxis at College Green to ease delays.

Mr O'Brien said the rerouting of 20% of Dublin Bus routes away from College Green had reduced pedestrian waiting times from a maximum of four minutes to just over three minutes.

But Mr O'Brien said the Luas is still not able to achieve its peak service of 40 an hour, only reaching an average of 22.

The introduction of 55 metre trams between now and April will cause more problems, adding there is just "not enough time for everything" in College Green.

He said it is "remarkable" that 301 of a total of 1,000 Dublin Bus routes servicing the whole of the city use College Street - which connects D'Olier St to College Green - during the morning peak hour.

A meeting of the council's transport committee heard the congestion at College Green after the introduction of Luas Cross City had caused traffic buildup back to O'Connell St and Bachelor's Walk.

An example of the congestion was the 83 bus from Glasnevin, which had its average speed reduced from 10km per hour to just 1.7km per hour. It took 30 minutes to travel 850 metres instead of 5km.

Assistant Chief Executive Dick Brady told the meeting that the council had wanted to reroute east-west traffic away from College Green to make way for the Luas but this issue was now going to be decided by An Bord Pleanála which is expected to hold an oral hearing in March.

Keith Gavin of the Irish Parking Association said the fear of his members is that this is pointing to further traffic restrictions.

He said the business group, DublinTown, had admitted that street footfall is down and one retail car park had lost 200,000 customers in 18 months.

Overall, a survey of eight car parks had found business down by between 2% and 20%.