For me or would be reducing service levels on quieter mid week days on intercity routes where they carry quite a bit of fresh air on some routes.
That can be easier said than done. Timetables are complex beasts, especially on intercity routes that interface with lots of other services along the way. Where intercity trains run every half-hour, they typically don't all have the same stopping pattern but some stations will only get an hourly service. If you just cut alternate services to only run an hourly service then some of those intermediate stations would lose their service altogether, so you would then have to either leave them out in the cold or adjust the timetable, which would then have knock-on effects on other services if on certain days the intercity services are running at different times.
To go with this increasing service levels at busier times or days of the week would seem sensible to deploy resources where they can carry most revenue.
While staff may, to some extent, be able to be redeployed from quieter times to busier times, as they are limited to working for only about a third of the full weekly roster, the same isn't true of trains. Taking some units out of service on a Tuesday doesn't give you any additional units to use on a Friday, and leaving busy station throats with fewer trains in the middle of the day doesn't mean you can push more trains through that bottleneck in the peaks. Infrastructure has a hard maximum limit on its usage, and the more its usage is skewed towards maximum at certain times of the week only and left relatively idle at other times, the more inefficient it becomes and the harder it is to cover its costs.
Combining more routes as through services across current TOC boundaries also has potential to save unit and crew diagrams in a GBR set up.
While combining routes
can bring about efficiencies, it can also bring about
inefficiencies as well.
The EMR service from Liverpool to Norwich is a prime example of this. A journey taking about 5½ hours, covering over 250 miles, and calling at 18 stations along the way.
Conventional wisdom is that the section of the route west of Nottingham is a lot busier than the section east of Nottingham, so is run with double units, with one of them decoupling at Nottingham and joining the next service heading back to Liverpool. It needs crew changes en route.
All of this adds a lot of complications. It increases the risk of poor reliability and punctuality. It is more restrictive when timetabling and diagramming because you have more dependencies to take into account. It limits your flexibility to adapt and adjust the service to meet emerging demands on one part of the route if those changes can't easily be accommodated on other parts.
Sure, there will be some instances where you can improve things by combining services, but where that is the case there's no impediment to making those changes now, services can and do swap between TOCs as needed. But the idea that this is going to be a
significant or widespread benefit from GBR doesn't stack up.
