alright, this is happening
big day for China & Vietnam relationship
Definitely a major and encouraging development for China and Vietnam indeed.
Speaking of the routes, the Hanoi-Haiphong-Hanoi and Hanoi-Lang Son HSR Lines definitely makes a lot of sense.
For the Hanoi-Haiphong HSR Line:
1. Hanoi and Haiphong are Vietnam's 2nd (8.5 million) and 3rd (2.1 million) largest cities respectively. Connecting them both means a much greater integration between both major cities, which should be a massive boon for the overall of northern Vietnam.
2. Hanoi and Haiphong are essentially Vietnam's Beijing and Tianjin, with Hai Duong in-between (which is similar to China's Lanfang). It would be considerably easy for Hanoi to replicate Beijing-Tianjin intercity relations onto Hanoi-Haiphong, should they desire to.
3. The regions connecting Hanoi and Haiphong are generally flat terrain, and with only ~90 kilometers separating the two cities, a HSR line is easily doable. (Guangzhou-Shenzhen is actually further apart)
For the Hanoi-Lang Son HSR Line:
1. From Hanoi to Long Son is around ~150 kilometers, which should be doable despite the increasingly difficult terrain going northwards of Hanoi. If anything, the Boten-Vientiane line located in neighboring Laos can sort-of become a textbook reference for Vietnam here.
2. Beyond Lang Son, there's only ~200 kilometers of straight-line distance left until Nanning. At present, the Nanning-Pingxian HSR line capable of 250 km/h has been built till Chongzuo, while the Chongzuo-Pingxian segment is under construction. Once the HSR segments on both sides are completed, Hanoi would have a direct HSR connection to Nanning.
3. Connecting Hanoi to Nanning through Lang Son and Pingxian means Hanoi (and the overall of northern Vietnam) will be better economically and socially integrated to the Pearl River Delta through further existing HSR connections to Guangzhou.
At the same time, while the northern HSR routes are being seriously worked at, China and Vietnam should probably start preliminary work on HSR route that would link Hanoi and Da Nang (5th most populous city in Vietnam), which means extending the HSR network halfway across Vietnam.
And speaking of Ho Chi Minh? Maybe they can wait for a little while.