Here's the overview from TFL:
We are consulting on proposals for a new, direct and quicker transport link between Sutton and Merton. We have called this the Sutton Link.
The Sutton Link would create a high-capacity route for people travelling between Sutton town centre and Merton using zero-emission vehicles. It would connect with other major transport services into central London and across south London, including National Rail, London Underground, existing tram and bus services. It would make journeys by public transport quicker and more attractive, and reduce the need for trips by private car.
Many of the neighbourhoods along the proposed routes have limited public transport options. The Sutton Link would support new homes being built and would improve access to jobs, services, major transport hubs and leisure opportunities across both boroughs and beyond.
Our work is at a stage where we would like to know your views about three potential routes. We are considering a tram or ‘bus rapid transit’ (BRT) for the Sutton Link and would also like to know your views on this.
BRT is similar to a tram but runs on road segregated from traffic where possible, not on rails, and carries fewer people in each vehicle. A full explanation is included below in the section titled ‘About trams and bus rapid transit’.
From LCC -
general principles would be ensure this doesn’t negatively impact cycle routes, that there are good routes to the stations/stops, that any places where cyclists will be crossing tracks are designed carefully with latest materials to avoid tramlining incidents, that the space comes from private car lanes.