Chiltern 165s and 168s working in pairs - timetable performance

[BanburyBlue]

Hi all.

As part of my normal commute from Banbury to Birmingham, the usual traction is a Chiltern 168. Occasionally a Chiltern 165 arrives, but despite its lower top speed, it seems to generally keep to time - may be a few minutes late by the time it reaches Birmingham. This has always been explained to me as being down to the better acceleration on a 165 vs a 168.

However coming home the other night, we had a four car train formed of a 2 car 165 coupled to a 2 car 168/3. Again, this train kept to time, and was only 2 minutes late on arrival at Banbury, and frankly most of that was down to waiting at signal for the line to clear outside Leamington Spa.

Surely in this formation you lose all the benefits so how does the train keep to time? I would assume that the 168/3 can't drag the 165 at a higher speed, and the 168/3 would have to match the acceleration of the 165?

Thanks.

 

[150219]

More due to the fact that the timings will be maintained more or less with a 165 unit. Depending on the stopping pattern and pathing/engineering allowances in the schedule too. The fact that it's only a couple of minutes can be as much as the delay will be. If there was ever a non-stop service from Birmingham to Banbury and then onto London timed at line speed, then there'd be more of a difference noticeable. Between Banbury and Birmingham in the standard timetable though, then not so much.

 

[Class2ldn]

Theres a lot of leeway built into the service generally between london and birmingham, the oxfords tend to be a bit tighter and you do notice the difference in timings on those if the stock is a 165 instead of a 168.

 

[Towers]

Similar scenario to a 150/3/5/6 being bolted to a 158, they’ll usually manage to keep to time thereabouts. Unless you’re doing sustained high speed running it’s surprising how little difference it can make.