The costs of East Side Access is almost entirely due to tunneling deep under one of the most heavily built-up areas on the planet, without disruption to either

The costs of East Side Access is almost entirely due to tunneling deep under one of the most heavily built-up areas on the planet, without disruption to either above-ground or underground activities. Musk's system, if it works, will cost a bundle on this fact alone. Any corridor that would justify such a high speed system would also be stupidly expensive to build through, both to acquire the rights to, and to construct without completely destroying everything along its path.