The line was built on the cheap because lots of naysayers proclaimed it would be a white elephant, and for some reason they were listened to. The sections that were supposed to be double track were cut back significantly to single track.
As a prominent campaigner described it at the time, penny wise pound foolish. Construction costs never come down in the future.....
No, the line was built on the cheap because the BCR was basically a basket case. Even with optimism bias, we had to strip back a couple of elements from the project to get it through a change of government.
Remember that this was the test case, there wasn't any project before this to reference it against. The bill passed in 2008, and there had been several years of studies before that; I first got involved officially in 2003.
Larkhall was still being built when we were doing the final business case in 2005 for the bill, and that was a short electrified stub of a suburban network; the business case for that one was obvious. Same with the Paisley Canal line. It took over a year of negotiations
after the Borders Line bill was passed before Airdrie to Bathgate even began building. It took four years after the bill was passed before a single spade hit the ground.
There wasn't another test case, nobody had any idea how the numbers would play out. No big new railway line had really been opened in the UK since the Robin Hood line in the 90s, although there had been the odd reintroduction of short stubs such as Bicester to Oxford. Nobody had decided to go and build anything more than 20 miles, especially not into the deepest darkest countryside.
When I did the original BCRs for the Borders line, we looked at everything. Thoroughly we looked at everything. We spent six months doing option shifting to see if we could figure out a way to justify anything beyond Galashiels. Even the half mile extension to Tweedbank had to be fought for tooth and nail, and that was basically justified on the basis of having space for a second terminating platform which could be used to hide a crippled unit in; the thought of charters was miles away.
We had to get everything through two changes of government, through different councils and through the absolutely awful relationship at the end with a couple of senior Edinburgh city councillors.
The deal we got was that every new piece of infrastructure could be built to double track width
or with clearance for wires. But that meant payoffs in other ways, to keep the cost down and the BCR high enough that it didn't just get cancelled. There was a phenomenal amount of goodwill and political support behind it, but politicians are still politicians, and they're answerable to taxpayers.
There were economies, such as a lack of intermediate signal sections on the loops, and the same severe speed restrictions on the bridges down the Gala Valley. It was justified on the basis of 2tph all stops, and so the specification was the bare minimum needed to run that efficiently. Bits were chopped to save money to keep the project moving.
If we had argued for a double tracked, electrified line throughout, the thing would never have been built, or it would have been cancelled halfway. There were economies, and there were a lot of tradeoffs to get it over the line, but it's there, it's getting electrified, and it serves 2tph.
In retrospect, maybe we could have spent more money on it, but we didn't. But without spending the money that we spent, and saving the money we didn't, then it wouldn't have been built, and a decade and a half later, we wouldn't be able to use the line to justify further reopenings.