Tuesday, December 03, 2019

Timetable Tuesday #51: A staggering mess - How 456's new timetable shortchanged Ballarat Road

You wouldn't think that routes mentioned in this PTV news item about Melton area buses would affect the Melbourne Public Transport frequent network maps. After all frequency on each is inferior to the every 20 minutes threshold I've adopted with the maps.   

However the changes involve Route 456 between Sunshine and Melton. The changes to it look benign and even beneficial. They will give the small residential community of Rockbank, an ill-advised 'middle of nowhere' 1970s-era development isolated from other routes, a doubled frequency with all trips stopping there. 

Route 456 also has a larger network role. It's part of a Ballarat Rd frequency corridor in conjunction with Route 426. Until recently, thanks to careful staggering of departure times, it provided a combined 7 day 20 minute frequency service between Burnside, Albion and Sunshine, a distance of about 9km. 

The 426/456 corridor serves residential areas around Sunshine West, Albion, Deer Park  and Burnside. Most of it is distant from trains. And any trains nearby are infrequent V/Line services stopping at widely spaced stations. Hence local buses are important.  

It's worth mentioning that the Ballarat Rd catchment is not affluent and local demographics are quite favourable for bus usage. And, although they're pedestrian hostile if there are too few crossing points, main highways are generally suitable places for fast and frequent bus services. 

The map below shows the area's Useful Network (every 20 minutes or better) up to yesterday. It was fairly comprehensive. But it relied heavily on multi-route bus corridors to provide the service. If one timetable was changed but not the other then intervals would be uneven, losing some of the benefits of the combined service. 

These corridors are fragile and only exist due to painstaking planning and coordination (in some cases involving multiple bus operators). One can't rely on their longevity since corporate memory in the Department of Transport is limited and the culture in parts can be operator and route rather than corridor and network based. Ideally transport authorities would be as vigilant about protecting combined frequencies on multi-route corridors as they are about maintaining car storage spaces at stations.  History shows that they aren't. 

The previous weekday timetables (shown in the peak direction to Sunshine) are below. Off-peak spacing of buses on the common section is fairly even, with 18 to 22 minute intervals. While 20 minutes isn't quite a 'turn up and go' service it can still be a convenient 'memory timetable'. And it meshes in with train services (also every 20 minutes). 

Offsetting overlapping routes like this is a cost-effective way of maximising combined frequency along a corridor. It is particularly suitable for routes that fan out from a centre (such as Sunshine) to populated and then less populated areas. In the case of 426 and 456, the 426 provides a local service to the Caroline Springs Town Centre while 456 runs to Woodgrove Shopping Centre in Melton. The populated trunk gets the more frequent service while the less populated outer gets a basic local service. If each route ran half as frequently as the train then connections with each train would be possible from the combined section if timings were right. 

The December 2 change altered Route 456 so that all trips go into the residential area of Rockbank. This is good for simplicity since only about half did before. However the diversion adds extra run time to the lengthened trips. This lessens flexibility when scheduling and coordinating bus timetables, including with each other and with trains. 

Weekday trips to Sunshine is a prime example. By itself the 456 timetable looks similar to the old one with the same 40 minute interpeak frequency. However when compared against the 426 timetable (which didn't get a change yesterday) trips become uneven. The 18/22 minute intervals before get replaced with lumpier 12 to 28 minute gaps. 

This means maximum waits approaching half an hour and uncertain connections with trains. Instead of a maximum 22 minute wait you could be waiting 28 minutes if you just miss a bus. While 'only' six minute it's still an increase of 27 per cent. The population of Rockbank (which might benefit) is much less than those near the long corridor from Burnside to Sunshine that got uneven, poorly-spaced buses from yesterday. 

The number of buses per hour on Ballarat Rd remains unchanged but their uneven scheduling means they don't qualify for a 'Useful Network' 20 minute service. Longer maximum waits make the service less useful while the short intervals reduce efficiency. Deleting them from the Useful Network maps creates a large service 'hole' that didn't before exist. 

Neighbourhoods to lose are in the seats of St Albans (Natalie Suleyman MP) and Kororoit (Marlene Kairouz MP). 

What about train connections? I'll assume Albion as the logical connection point since it's the first station that the bus reaches and the bus/platform walk if shorter and faster than Sunshine (despite the latter being a new/rebuilt station). 

Weekday off-peak bus > train connections (towards CBD) were 3 to 5 minutes under the old 456 timetable. The 426 timetable (which hasn't changed) is similar. The new 456 timetable changes off-peak connection times to 14 minutes. This is excessive and slows trips involving a connection by about 10 minutes. Those to lose include those taking the 456 from Rockbank to access more frequent trains on the Metro network. 

Routes 427 is also affected by this timetable change. When it (and the 428) were first implemented (back in 2014) their run time was excessive. Buses would often spend too much time waiting at time points along the route. 

This timetable should (finally) resolve these issues. A further benefit is that this timetable reform enables is that Route 471 (run by the same operator as 427 and 428) gets a frequency boost (20 to 15 minutes) during some peak periods. The trade-off is that spacing on Forrest St between the overlapping routes 400 and 427 become less even. Even staggering, such as was achieved when the Brimbank network started in 2014, would have provided an even 20 minute service 7 days per week with Route 400 along Forrest St. 

You can see the effect of the sparser Useful Network on the map above. The increased unevenness of service causes increased maximum waits. This represents an effective cut in service even though the number of buses per hour on key corridors hasn't changed. While Rockbank benefits from a better local service, my hunch is that the patronage gain from this is unlikely to outweigh the loss caused by the degraded service along Ballarat Rd. 


The new Route 456 timetable would not have been simple to draft. It has more interdependencies than other bus timetables. These include: 

* Connectivity with trains (pretty standard for bus routes)
* Increased run time due to routing all trips into Rockbank (reducing scheduling flexibility)
* A need to offset with Route 426 to retain even headway on Ballarat Rd
* Arising from above a need to coordinate with Transdev (who run the 426)

It would appear that a trade-off has been made at least on weekdays off-peak. That trade-off has made service worse for many if not most of its users. Ballarat Rd loses its relatively even headways. And train connections at Albion have been abandoned, making some trips 10 minutes longer. 

The silver lining is that those in the residential parts of Rockbank get more buses and a confusing deviation is removed. 

Do you think that this trade-off was worth it? Personally I don't think so. The 456 may be a victim of one route trying to do too much. As the area grows even more than already planned routes will be needed. Anyway please let me know what you think in the comments below.

PS: An index to Timetable Tuesday appears here.

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