TRANSPORT chiefs are being forced to design a way for trams to run between two city centre streets without scraping the road.
Technical problems at the junction of Queen Street and North St David Street mean tram cars could be damaged.
A senior insider says the higher-than-usual camber on the junction has caused headaches for designers over the past two years.
But TIE, the council's transport firm behind the plans, today insisted it can overcome the design issue. It said the nose on the tram cars can either be re-shaped to ensure the vehicles don't scrape the ground, or the road level flattened to ensure a smooth ride.
A final decision will be taken in the coming months, as the system design team finalise plans.
A TIE spokeswoman said: "The corner at York Place offers us an engineering challenge, but in constructing the network one option is to amend the camber of the road to promote smooth running.
"This is part of the system design, which is currently underway. In addition, the vehicles have not yet been identified, but they will be designed in such a way to further ensure that scraping does not occur. Scraping will not be an issue for the Edinburgh tram."
But the Evening News' source said the New Town junction has proved the most troublesome section of the network for designers. "The problem was identified a few years ago, and nobody was able to find a solution," the insider said. "Put simply, under the present plans, trams will hit the deck as they go between Queen Street and St Andrew Square.
"It has proved to be a key problem in the route selection, and although trams will go fast enough not to ground, there could be a lot of damage done to the vehicles over time.
"It doesn't matter what make of tram you have, they all have an over-hang. And you can't alter the camber of the road, because there is a tunnel below and if you go any deeper the street could collapse."
However, the TIE spokeswoman said it would be possible to add extra layers to the road, and level the camber that way. This requirement could be included in the contract to build the network, which will soon go out to tender.
And TIE said a specific design of tram could be included in the final contract for the vehicles, with a higher over-hang to ensure it doesn't catch on the road.
The spokeswoman said: "There are four companies currently bidding for the [tram car] contract, and they are well aware of the environment in which their vehicles will operate, and will tender their options accordingly."
TIE has now been handed more than 30 million to draw up detailed design plans. A final business case must be presented to both councillors and Scottish ministers by the end of the year.
This will reveal how much of the 714m proposals are realistically affordable, with current estimates ruling out anything other than one line from Leith to the firstname.lastname@example.org