Passengers travelling on the East Coast and West Coast main lines will benefit from more services and extra seats once the HS2 high-speed rail project is completed, the Department for Transport (DfT) has said.
The frequency of commuter and intercity trains to Birmingham, Manchester and Leeds could "almost double" to 48 per hour, officials claimed.
The number of seats could treble to around 15,000, according to the DfT.
The department acknowledged that many intercity services are currently "full to overflowing" but said that with HS2 they "will not be so crowded".
Phase 1 of the £55.7 billion HS2 railway is due to open in December 2026 and will see trains travel at high speed between London and Birmingham before running on from Birmingham on the existing West Coast Main Line.
A second Y-shaped phase, taking the high-speed line to north-east and north-west England and beyond, is due to be completed by around 2032/33.
Transport Secretary Chris Grayling said: "Our railways owe much to the Victorian engineers who pioneered them, but we cannot rest on their legacy when we face overcrowding and capacity problems.
"HS2 is an ambitious and exciting project and the Government is seizing the opportunity it offers to build a transport network fit for the 21st century, one that works for all and makes clear to the world that Britain remains open for business.
"The full HS2 route will be a game-changer for the country that will slash journey times and perhaps most importantly give rail passengers on the existing network thousands of extra seats every day. They represent the greatest upgrade to our railway in living memory."