The UK does have plenty of track: 20,000 miles worth, along with 6,000 level crossings, 30,000 bridges and viaducts, 2,500 stations...
Track needs constant maintenance through ballast redistribution and compaction to maintain track geometry; the rail itself needs to be ground regularly to maintain its shape; points systems need to be maintained, as well as signaling systems, earthworks and embankments, even vegetation.
Network Rail spends billions of GBP every year maintaining the railways.
Many.
> Most track is 200 years old
And have been relaid about 30-40 times since then.
About the only thing that dates to 19th century are the rights-of-way.
No, it's zero. Commercial airlines last about 30 years, they have metal fatigue from pressurisation cycles.
"And have been relaid about 30-40 times since then."
Are those expenses comparable to earthworks and contraction involved in laying down new line?
Look, I just opened up flightradar24 and clicked a random plane. That was G-DHKC, a 757-256, first flight 1989. 33 years.
And that's just a random pick. There are many airframes from mid-late 1970s still flying commercial.
> Are those expenses comparable to earthworks and contraction involved in laying down new line?
What do you mean by that?
Your random choice also did hit an interesting quirk in aviation that cargo airlines tend to use old aircraft that are no longer fit for passenger operations.
There are several reasons for this, but cargo ops are able to use their aircraft in ways that maximise their life [1]. Passenger airlines try and maximise the time each aircraft is airborne (i.e. earning revenue) whereas cargo operators often schedule differently. This sometimes allows for operation of aircraft that have very few pressurisation cycles left in their lifespan.
The specific aircraft you found was retired from passenger ops in 2016 (after being in storage since 2015) from Icelandair when DHL purchased it [2]. This is when the airframe was 16 years old. It was converted to a freighter variant at this time - the 757-256.
You can look at fleet ages to get an impression for the age of aircraft, and generally passenger airlines (especially in developed countries) are using newer planes and cargo airlines have a much older fleet. You might have noticed this when you see old fashioned designs like tri-jets, or four engined jets like the 747 only in cargo livery at airports.
[0] https://www.planespotters.net/airframe/boeing-757-200-g-dhkc...
The train is several times cheaper than a plane, seats 10x more people and some of machines used in UK were built in the 70's. How many airplanes keep flying that long?
Infrastructure? Hs2 is the first track of rail in UK in over a century! Most track is 200 years old, so it has paid for itself a hundred times over.