[New Brisavoine]

Originally Posted by nito

Whilst HS2 and Tours to Bordeaux are both high-speed rail projects, they aren’t really comparable in what they are attempting to deliver; the latter is a relatively uncomplicated railway project running through areas with low population density and limited catchment (Tours, Poitiers, Angoulême, & Bordeaux have a combined urban population of c.1.1mn)

Tours, Poitiers, Angoulême, and Bordeaux have a combined population of 2.1 million. 1.1 million is the population only of Bordeaux.

Originally Posted by nito

with limited engineering obstacles.

Hm, limited engineering obstacles... they have to cross two rivers which are each twice the width of the Thames River in London... And also there is the complicated link between the high-speed line and the central train station of Poitiers, with a long and costly viaduct over the maze of roads, freeways, and local railway lines in the suburbs, of which I have shown pictures in post #510. For the rest of the itinerary, the terrain is not very different from England. It's not like there is the Alps lying between London and Birmingham.

Originally Posted by nito

involves problematical engineering hurdles through densely populated and scenic protected environments. The majority of the route is either in tunnel, cutting or viaduct

Not very different from the high-speed line from Lyon to Marseille that cuts through scenic and protected areas of Provence, including world-famous vineyards (Côtes-du-Rhône). It required many tunnels and viaducts too. And it was completed already more than 10 years ago.

Originally Posted by nito

and will require the construction of several expensive stations to accommodate the 400m long trains.

Uh, there's nothing exceptional there. TGV train stations in France are also 400 m long.

For example the Avignon TGV train station, in the middle of scenic Provence, and inside a dense urban area:

Originally Posted by nito

For instance, when HS2 departs London Euston it immediately enters a tunnel and doesn’t emerge until the outskirts of London.

It's exactly the same for the high-speed line from Paris to Bordeaux. When it departs from Paris Montparnasse station, it enters a long series of tunnels until the very last southern suburbs of Paris. The length of tunnels is nearly 14 km (8.5 miles). There are also dug trenches between those tunnels. This line is in fact the most disappointing one (for urban enthusiasts) when you travel to Paris, because you see absolutely nothing of the huge megacity until almost the end when you arrive at the Montparnasse station.

This is the TGV emerging from the last tunnel at the end of the southern suburbs of Paris:

Originally Posted by nito

(with the exception of Old Oak Common station which will be in a giant trench similar to Stratford International)

Not very different from the Massy TGV station in the southern suburbs of Paris, on the Paris-Bordeaux high-speed line. The trench was covered and the TGV station built above.





All of this to say that there is nothing particularly extraordinary about HS2. The same obstacles were met and solved on the continent already in the 1990s, 2000s, and now. You could argue that England has a higher population density, but the population density in the suburbs of Paris and in the busy corridor from Lyon to Marseille is the same as on the HS2 route. If anything, it was much more complicated to cut a high-speed line through the densely populated, rugged, and very scenic Provence than though the English countryside. There were insane legal battles to stop the high-speed line in Provence, but in the end the opponents failed and it was built.











And regarding launching several projects at the same time:

Originally Posted by nito

Complicating matters further is that the projected passenger volumes on HS2 mean that the network isn’t a self-contained project and would require additional improvements across the wider network. For example at London Euston, HS2 is simply unworkable without the construction of Crossrail 2 (c. 28-35 route km of new tunnelling) which would be one of Europe’s largest infrastructure projects in its own right.

Lines 14, 15, 16, and 18 of the future fast subway of Paris (Grand Paris Express) will be Europe's largest infrastructure project. It's not 28-25 km of new tunneling we're talking about here, but 200 km.



And yet France launches the Tours-Bordeaux high-speed line (+ the Tours-Rennes, and Lorraine-Strasbourg high-speed lines, the latter including a tunnel under the Vosges mountain range) while at the same time launching the Grand Paris Express. Some high-speed links are also planed in the suburbs of Paris to join the Paris-Strasbourg and the Paris-Bordeaux high-speed line, via Orly Airport (thus allowing to travel by high-speed train from Strasbourg to Bordeaux without having to change trains in central Paris).