First of all, trams will be part of the traffic.
Secondly, with segregation of trams and properly-managed traffic light sequences etc where trams and other vehicles mix, then traffic flows, both of trams and other vehicles should not be disrupted.
And in any case, it only stands to reason that vehicles carrying around 200 people (i.e. a tram) should have priority over vehicles carrying 1, 2, 3 or even 4 people (i.e. a car).
TRAFFIC is made up of buses, cars, taxis, lorries, cyclists and soon trams (with any luck).
There is an assumption that traffic equals cars and that cars have priority – you see this in discussions about bus lanes, which somehow cause congestion, despite the fact that they carry way more people than the non-bus lanes.
The fact is that transport policy is about the flow of people through the streets, not cars. It is all about efficient use of space.
I found this quote on a site about public transport myths in Melbourne, Aus:
“The basic traffic problem is moving people, or goods, and not, as commonly and erroneously supposed, moving vehicles…. [A] traffic count taken by the Town and Country Planning Board in 1947 showed that in the heaviest half-hour of the peak Swanston Street trams carried 5,472 southbound passengers over Princes Bridge on one track, while in the same half-hour two lanes of motor cars and taxis carried 727 people, including the drivers…. It is therefore apparent that public transport is by far the most economical user of street space when considered in relation to the number of passengers for which it caters.
—Major-General Robert Risson, Journal of the Institute of Transport (Australian section), August 1955″
It is 50 years old that quote, but it is as true now as it was then.