The Dublin Transportation Office (DTO) has insisted that up to 60 trams an hour in each direction could cross the Red Cow interchange in west Dublin without causing traffic delays, when the route opens in a little over a month.
Luas trams will not be able to call on priority signalling at the traffic lights at the interchange, as they are able to do in the city sections of the Sandyford-St Stephen's Green Line.
Nevertheless the DTO maintains that the modelling it has envisaged for the Red Cow would not cause disruption to existing traffic, and that the proof of this is shown by the absence of delays while Luas is testing.
The Red Cow interchange connects the State's busiest road, the M50, with the State's second-busiest, the N7.
They carry about 80,000 and 60,000 vehicles per day respectively at the point where they meet.
Luas is to cross three level crossings at the interchange until a €200m programme to upgrade the junction to "free flow" status is opened in about two years.
The Railway Procurement Agency (RPA) said yesterday that, while testing was ongoing, it expected to be in a position next week to announce a start-up date for the Tallaght route.
A spokesman said that the "target date" was still August, "and we will be hoping to keep as close to that as possible".
The testing process was more complex than that on the Green route, as the Tallaght (or Red) route passed through some 40 sets of traffic lights over its 40km route.
