The argument for HS2 begins with the difficulty of upgrading the existing main lines while keeping their traffic moving. Neither the East Coast nor the West Coast route has enough room to absorb all the other's services. A new passenger route would allow traffic to move away from whichever main line was being upgraded, while freight could use the remaining route. Construction through central London and other cities helps explain the expense. In response to concerns about bottlenecks around Euston, Birmingham, and Manchester, the proposed additional lines, signalling changes, sidings, and runarounds are defended as ways to increase throughput. Work on east-west routes is also mentioned, although it receives less attention than HS2.
Notable Point · 3:40:42-3:44:01
The case for HS2 as room to upgrade existing main lines
Additional passenger capacity is defended as a way to move traffic during East and West Coast main-line upgrades and relieve bottlenecks.