TfL buses timekeeping requirements

[Nigel]

Yesterday I did a circumnavigation of London using the Superloop network. I managed to complete it much more quickly (in 7¼ hours) than I originally thought was possible (8½ hours).
The reason for this was that while nearly all the buses I caught left their starting point at the time indicated on the timetable, thereafter they made no attempt to wait at any stops when ahead of their schedule. Most of the buses in the morning, before traffic started getting bad, arrived at their final destinations significantly early. The most extreme being the SL7 which arrived at Heathrow Airport 10 minutes early, having been this early nearly all the way from Kingston. These early arrivals meant that at most interchanges I could catch the bus before the one I thought I would be able to connect with.

In other parts of the country, I find that buses assiduously wait at their timing points, so that they don't get ahead of schedule. Is the requirement different in London, because the timetables at the stops usually just show a frequency, rather than specific times, other than for the early and late departures in the day? (That said, even the early morning buses that I caught, for which the TfL website lists specific Saturday times until 0900, still got ahead of their schedule.)

 

[Bishopstone]

High frequency buses in London operate on the principle of maintenance of headway so that - as far as possible, and wherever you are on the route - a bus will be along every 10 minutes (or whatever the advertised frequency is), but not to a specific public* timetable. Drivers have displays in their cabs that prompt them to hold back, if they're getting close to 'bunching' with the bus in front.

Low frequency routes are required to run to a timetable in the conventional way.

Of course, both systems can disintegrate in the event of unforseen road conditions, or incidents on buses etc.

* There is still a 'back office' timetable, to the minute, used to roster staff etc and inform drivers when they should be leaving termini and taking their breaks.

 

[greenline712]

Because, in London, operators are penalised if the EWT (excess waiting time) is exceeded, so the headway is king. The danger is that, if the service continually runs early, eventually a long gap will occur, and the EWT target will be breached.
The other problem in London is that running times are now so padded out (see EWT adherance above AND the proliferation on 20MPH zones) that drivers are often told to wait for time, sometimes several times along the route.
Trying to come up with realistic running times for routes is nearly impossible ... the easy answer is to pad out the timetable, which all costs extra buses and driver's ... and no-one seems to care.

In the meantime ... well done!! I'm not sure my bottom would gave lasted for over 7 hours!!!

 

[NCT]

Because, in London, operators are penalised if the EWT (excess waiting time) is exceeded, so the headway is king. The danger is that, if the service continually runs early, eventually a long gap will occur, and the EWT target will be breached.
The other problem in London is that running times are now so padded out (see EWT adherance above AND the proliferation on 20MPH zones) that drivers are often told to wait for time, sometimes several times along the route.
Trying to come up with realistic running times for routes is nearly impossible ... the easy answer is to pad out the timetable, which all costs extra buses and driver's ... and no-one seems to care.

Thanks for describing something I have long observed.

What puzzles me is the balance of incentives.

Are the incentives so one sided that it's always better to pad out the timetable and not take the hit on EWT? I'm surprised no operator has tried to submit lower cost bids with lower PVRs based on faster running times, but with a larger contingency for bigger EWT payments.

 

[greenline712]

Thanks for describing something I have long observed.

What puzzles me is the balance of incentives.

Are the incentives so one sided that it's always better to pad out the timetable and not take the hit on EWT? I'm surprised no operator has tried to submit lower cost bids with lower PVRs based on faster running times, but with a larger contingency for bigger EWT payments.

You would think so . . . and sometimes operators will schedule a route more tightly in the expectation that the savings on drivers and buses will outweigh the loss of the EWT payments. The drawback is that TfL will perceive that the route fails its performance targets too often, thereby (in the worst outcome) giving them the ability to terminate the contract early. No operator wants to get that reputation. In addition, TfL won't just withhold bonus payments, but also levy a performance "fine" if targets are always missed.

There is a fine balance to be steered when tendering for and running a TfL contract. That is why new operators are seemingly loathe to enter the market in London, and why smaller operators don't usually do well . . . Sullivan Buses being the most recent. It is no longer the easy market that it was . . .

 

[Nigel]

Thank you for all the information - it is a revelation to me. But it begs the question of which, if any, advertised times are considered sacrosanct in London. For example, are first and last bus timetables generally adhered to (i.e. not departing early). On occasions when I need to catch an early flight from Stansted Airport, before the first tubes have started running, I have caught a bus at 0502 that gets me to Tottenham Hale to connect with the Stansted Express. While I always get to the bus stop a few minutes before the advertised departure time, and it has always been bang on time, I would not be pleased if I arrived just before 5am to see it already disappearing into the distance!

 

[greenline712]

Thank you for all the information - it is a revelation to me. But it begs the question of which, if any, advertised times are considered sacrosanct in London. For example, are first and last bus timetables generally adhered to (i.e. not departing early). On occasions when I need to catch an early flight from Stansted Airport, before the first tubes have started running, I have caught a bus at 0502 that gets me to Tottenham Hale to connect with the Stansted Express. While I always get to the bus stop a few minutes before the advertised departure time, and it has always been bang on time, I would not be pleased if I arrived just before 5am to see it already disappearing into the distance!

A low-frequency (4 BPH, or every 15 minutes) timetable is operated differently . . . timetable adherence is everything! In general, very early and very late buses are more likely to maintain time along the route . . . these running times are easier to predict, as traffic is much lighter (although Friday and Saturday nights can be difficult . . . some routes have a different Friday evening timetable, depending on where the route runs).

Night bus routes are almost always run to adhere to the timetable . . . regular night bus drivers understand the importance of not running early.

 

[Nigel]

A low-frequency (4 BPH, or every 15 minutes) timetable is operated differently . . . timetable adherence is everything!

Thanks - what is supposed to be the practice if the frequency is exactly 4BPH. For example the first bus I caught on Saturday, the SL2, is 4BPH from the start of business at 5am until 0845. Yet the departure I caught around 0630 was about 3 minutes ahead within 15 minutes of departure, and 5 minutes early towards the end of its route.

 

[mb88]

Interesting discussion folks and a welcome reminder of my time driving in London with Go Ahead at Orpington (MB) and latterly Stagecoach Bromley (TB) garages. One discrepancy that always stuck out for me with regards to the low frequency vs high frequency, schedule deviation vs headway situation was when a route had had was high frequency during the day but low frequency in late evenings. For example, when the 320 first received its extension to Catford (around 2011 if I remember correctly) the daytime frequency was 12 minutes, dropping to 20 minutes at night. However, there always seemed to be a bit of confusion as to whether buses should adhere to their scheduled times once the frequency reduced, or continue to operate on a headway basis as per the daytime frequency? Any service controllers or other experts on here that can clarify?

 

[greenline712]

Interesting discussion folks and a welcome reminder of my time driving in London with Go Ahead at Orpington (MB) and latterly Stagecoach Bromley (TB) garages. One discrepancy that always stuck out for me with regards to the low frequency vs high frequency, schedule deviation vs headway situation was when a route had had was high frequency during the day but low frequency in late evenings. For example, when the 320 first received its extension to Catford (around 2011 if I remember correctly) the daytime frequency was 12 minutes, dropping to 20 minutes at night. However, there always seemed to be a bit of confusion as to whether buses should adhere to their scheduled times once the frequency reduced, or continue to operate on a headway basis as per the daytime frequency? Any service controllers or other experts on here that can clarify?

In contract terms, if the route is better than 5 BPH in the daytime, but lower in the evenings (4 BPH), then the route is classified as high frequency. Operationally . . . frankly it can go both ways!! Most controllers would try to maintain timetable throughout the evenings . . . if only because it made it easier to run last buses on timetable time.

My time as a driver and a controller was mainly in the 1990s . . . when headway wasn't so important; we were measured on mileage operated, so the "quality" of the mileage wasn't so relevant. Personally, I would do everything to run the last hour of the timetable correctly, even if it meant that the service between 2100 and 2300 wasn't of the best . . . if the day had been especially bad, then that would still take some doing!

Just occasionally, the "controller's lament" would apply . . . "All buses will return to the Garage at some time; and tomorrow we'll start again!".

 

[Statto]

You also need to take account for the express nature of the SL7 (& other Superloop routes), after Kingston Town Centre the service has 2 stops (Teddington & Hatton Cross Station), until Heathrow, so buses can arrive early under the right traffic conditions, thats a bit more awkward to do on a stopping service.

 

[Goldfish62]

In contract terms, if the route is better than 5 BPH in the daytime, but lower in the evenings (4 BPH), then the route is classified as high frequency.

It's actually 5bph or better, rather than better than 5bph, but I think you probably meant that.

However, the latest service planning guidelines indicate a subtle change, stating that anything better than 4bph is considered high frequency. This is why more recently there are examples of high frequency routes running every 13-14 min.