Venturi effect could be used to make it a constant head of pressure. Or you could use a turbine with variable pitch and an infinitely variable transmission.
There's another, called Burlington, on the Great Western mainline - after you go through Chippenham en route to Bristol, there's a point in the long tunnel, which leads to the bunker station. It was where the government were supposed to scurry off to in event of nuclear war. Enough space to support thousands.
We have about 8 million end-users use our service daily, between our 100 or so clients. We have about five folks at clients who complain, vociferously, continuously, at all hours of the day and night, and it's unbelievably demoralising, as it's not so much "you mostly hear from the haters" as "you only hear from the haters, and you'll hear from them 10x a day for years on end".
I'm pretty close to jumping off or under something.