There are so many potential sites and most suffer from four basic shortcomings that need to be resolved before any platforms and revised signalling can be provided, usually, by Network Rail.
1. By adding an extra stop on an existing line how much would need to be added to the end to end timings of stopping trains, and how much free capacity exists to avoid delaying trains (passenger and freight) that don't stop.
2. Access to the new station, with particular reference to parking, bus interchanges, cycling and walking routes. Safe road and pedestrian access is vital.
3. Who can provide the finance to pay for the construction.
4. If a new station is opened will it abstract significant passenger numbers from existing stations?
Too often a combination of these makes an outwardly reasonable proposition seem unviable.
I'd also mention that adding back demolished platforms and increasing platform lengths at existing stations would be a good idea to help improve capacity at lower cost than opening totally new stations.
To illustrate these points, Dronfield was reopened about 30 years ago and is well used. Derbyshire county and local councils gave support. Users have been attracted to direct services to Leeds and Nottingham as well as Chesterfield and Sheffield, some of that traffic abstracted from Sheffield and Chesterfield. Users would like more trains to stop, especially for London and Cross Country services. This is currently being resisted by TOCs as it would add at least 3 minutes to the timetable for each additional stopped train, and delay other trains. Parking is now,a big problem.
Calls to rebuild Beauchief, Abbeydale and Millhouses, and Heeley stations all currently fail for these reasons, as does rebuilding mainline platforms at Dore & Totley.
At present making the current network more resilient must be a priority. I'm sure a few places do justify a new station which can prove viability, but it's possible that would have to be at the expense of dropping stops elsewhere - or even closing stations. Certainly there must be a lot of stations that could have been better situated if built new today.
