The stop locations,as well as the timing and funding of the Metro West project,are a matter of political debate. The Transport Minister,Andrew Constance,has said he would like to see a sub 20-minute journey from Parramatta to the CBD. Labor’s transport spokeswoman,Jodi McKay,has said she is not wedded to the 20-minute travel time,and would like to see a Sydney University stop considered.

The state government ear-marked $3 billion in last month’s budget for the project,but has said it would not be finished until late next decade. There is,however,a large project team already at work on the scheme,and there is a good chance the state or federal government could promise to accelerate work on the line ahead of coming elections.

The federal Labor opposition has committed $3 billion to the project,one of the main justifications for which is the need to relieve pressure on the existing T1 Western Line.

Fitting another rail tunnel under the city is a difficult exercise;the new line would need to traverse building basements,as well as the underground Eastern Suburbs and Illawarra Line,and the tunnels being built for the City and Southwest metro project.

The risk and complexity of construction in the CBD was highlighted over the weekend when an excavator on the City and Southwest project hit a gas main in Martin Place,forcing a prolonged evacuation of the area.