The high-speed rail link - HS2 - promises to cut journey times and relieve congestion on the West Coast Main Line.
But the full scale of what London would face during the construction is only gradually emerging.
While most of the route in London will be underground, most of west London's Ealing will have HS2 on the surface.
The impact of building it could be severe. Ealing Council says 18 bridges will have to be replaced due to HS2, and the Hanger Lane gyratory replaced.
Hanger Lane is one of the busiest intersections in London. Nearly 10,000 vehicles an hour pass through there at rush hour.
Clearly that would cause huge disruption.
In total the bridges that would be replaced will be:
- Three footbridges (two overbridges, one underbridge);
- 12 road (five overbridges, seven underbridges);
- One rail overbridge;
- One river underbridge;
- One canal underbridge.
The council is, with some caveats, supportive of HS2 but wants Ealing to be tunnelled under.
It puts the cost at £150m.
Local campaigners do not want HS2 at all, but if they have to get it they want a subterranean solution.
HS2 Ltd obviously realises the council has a point and is now carrying out a tunnelling feasibility study.
What will be difficult for the company to answer is, why is nearly everywhere else in London deemed suitable for a tunnel and not Ealing?
If areas such as Ruislip, where residents campaigned successfully for the route to go underground, why not Ealing?
Ealing, run by a Labour council, is more densely populated than Ruislip, which is in the jurisdiction of the Tory-led Hillingdon Council, and many will begin to wonder if politics is coming into play.
A spokesman for HS2 Ltd said: "Our contractors are undertaking a study looking at the effects of building a tunnel through Ealing compared with using the existing rail alignment next to the Central Line - taking into account the environmental impact and cost.
"We expect to have the preliminary report from our engineering contractors by the end of October.
Ultimately the decision will be made by the secretary of state for transport.''
Certainly replacing 18 bridges in Ealing will cause significant problems for the whole area and those who travel through it.