The High Speed 2 fiasco in the UK has prompted me to update my map of high-speed rail in France. Obviously the two countries are frequently compared, and here's more in that vein in relation to HSR.
1) Population density is much lower in France than in the UK. This can be seen by simply inspecting the existing and proposed lines in either country in satellite view, and it is backed by data. The island of Great Britain is 80,823 sq mi (209,331 sq km) in area and had a population of approximately 64,500,000 in 2021, for an average population density of 798 residents/sq mi (308 residents/sq km). Continental France is 206,665 sq mi (535,261 sq km) in area and had a population of approximately 65,500,00 in 2022, for a population density of 317 residents/sq mi (122 residents/sq km). Great Britain is approximately 2.51 times as dense as continental France, and continental France is 39.8% as dense as Great Britain.
2) France is somewhat better at containing urban sprawl than the UK. This is a qualitative observation on my part, and it isn't uniform across either country.(*) Areas of France such as the wider region around Lille or the Mediterranean coast from Marseilles to the Italian border are very sprawled out, with little countryside between developed areas except where the geography makes building impossible. And the UK has compact, relatively contained cities and towns, such as Norwich and Yeovil. But, overall, I think sprawl is less of a problem in France.
3) The combination of the previous two points means that the French routing strategy of connecting HSR lines with existing urban stations via "off-ramps" to legacy lines works quite well. The existing approaches to the central stations are fairly direct, and the off-ramps can be built fairly close to the cities. France generally has avoided building new approaches or stations within existing urban areas. Lille is the only exception so far. In contrast, the UK has decided to heavily rebuild existing stations and build new approaches in Birmingham, London (completion uncertain), Manchester (recently canceled), and Leeds (canceled a few years ago). The prices of those stations has become outrageous and are part of the reason HS2 has been so severely curtailed.
4) France has built a number of stations directly on new LGVs. Some have been built because there is no classic line near the new HSR line, some because there is only a classic line on one side of a city, and some because the nearest city is too small to serve with off-ramps. Some stations are connected to the nearest city with legacy rail or a tram system, but others are fundamentally car-oriented, with only limited bus service. Overall, I think the success of these stations is mixed. A few stations serve an attraction directly, such as the CDG station and the Disneyland station, and these are more successful in terms of passenger counts. However, the very rural "beetroot" stations are relatively cheap to build, so they may be successful financially. In the UK, the inline stations at Old Oak Common and Birmingham Interchange are fairly complex and expensive, though they should have high utilization.
5) Paris is semi-central to the country, whereas London is closer to being at one end of the country. France needs to build a lot more track-miles to fully connect the country, but as explained above, most of those miles were or will be much cheaper to build. But the main advantage to being central is that the rest of the country does not connect to the capital through just one link that risks being saturated before demand is completely met. Each link to Paris can absorb a large number of passengers coming from a smaller number cities. In the UK, the rest of the country will be funneled through one link.
6) On the purely practical side, France has completed 1,699 miles (2,735 km) of HSR track starting in 1981. The UK has completed only 70 miles (113 km) starting in 2003. France simply has vastly more experience at everything related to HSR, including track design and construction, rolling stock design and construction, and operations.
7) Both of my maps are fantasy maps. However, the French one is much more realistic
because my suggestions use the same routing principles as the French
have been using for decades, and the resulting alignments have been much
cheaper to build than HS2 in the UK.
All of the above raises the question: is there any way for the UK to "catch up" with France? No, not directly. The UK will never need to build as many HSR track-miles as France. Nor will it ever be able to build as cheaply as France given the substantially different human geography of the two countries. The UK could and should learn a fair amount from France, but the former country should also look to places like Japan, South Korea, and Germany for lessons. Those countries have population densities of 840, 1,340, and 600 residents/sq mi (326, 516 and 233 residents/sq km) and so have more experience in building around existing populations. The UK also needs to look inward and try to understand why HS2 turned out to be so expensive. If the UK adapts, it might be able to catch up with France qualitatively, connecting a large portion of its population via HSR, but the UK will need to change a lot to do so.
(*) The relative sprawl of each country probably has been analyzed quantitatively, but since I am an amateur, I don't feel the need to track the studies down.
