Monday, April 25, 2011

Space Travel on The Orbiter


"As any bus passenger will tell you, a twenty minute wait is three 
to four times longer than a ten minute wait!!"

Above; The classic example ! Two buses arriving simultaneously after about a 20 minute wait (another passenger at the same stop said "yesterday I had to wait 25 minutes"). 



Passing two buses in The Orbiter service heading in the opposite direction, about two minutes later, crossing Brougham Street expressway.


After shopping in Barrington Mall I rejoin The Orbiter opposite Spreydon Library heading north.  After a lengthy period in which quite a few passengers gather - again - two buses arrive simultaneously

Recently I have taken to using The Orbiter and The Metrostar more often than normal. This is partly because these cross-town routes offer potentially faster journeys than the radial routes which have been split in half and rejoined with sellotape!


Traveling around town on The Orbiter can be faster than cutting across town. Also, unless transfers can be done more or less continuously, hop off one bus route/hop on another bus route with less than ten minutes wait, I'd rather spend the extra time sitting on the one bus and travel a bit further and longer. One advantage of both these cross-town  routes is frequency - The Metrostar runs at 15 minute intervals (official term = headway) and generally does. The Orbiter - Christchurch's most heavily patronised route - service is advertised as running at ten minute headways. Yeah right.


Both times I boarded The Orbiter (see photos above) the other passengers and myself had a wait far longer than ten minutes. In both cases after a gap of around 20 minutes, two buses arrived simultaneously. As any bus passenger will tell you,  a twenty minute wait is three to four times longer than a ten minute wait !! (perhaps scientists who explain Einstein's famous theory of relativity using trains in examples should try using buses to explain black holes).  Longer "waits" for short hop regular urban journeys dynamically change the whole nature of bus travel and induce significant psychological changes in those waiting!

A service every ten minutes? This is a product being falsely advertised and Metro should do something about it. Such very long delays should not be happening. If a service is advertised at ten minute intervals it should arrive at ten minute intervals or very soon after. It is as simple as that. Eight minutes late can kill any chance of a transfer connection - in the present post-earthquake restricted service situation leave people sitting roadside with a 60 minute wait! [believe me, I know!] 

We can land a man on the moon, create mini-computers in cell phones, do micro-surgery on heart valves etc,etc ....but we are meant to believe that the city and Metro can not organise a bus system that keeps effective time?  Get real. 


Yes there are heaps of factors behind the photos up above such as it is school holidays, extra post-quake traffic congestion, ruptured roads from earthquake damage, that put stress on the bus system.   But a closely timed circuit route through Christchurch's busiest of suburban hub areas is always going to encounter delay and the sort of patterns - big gap then two buses - did not begin with earthquake. I gave up trusting The Orbiter as a morning peak commuter service link - from Shirley Road to Linwood - after the "ten minute" service turned up 25 minutes late one morning, making me embarrassingly late for work [which also involves a timetabled delivery]. The potential for delay and "slippage" of the gearing in The Orbiter route is huge. Trying to run it as a conventional timetable route, I suspect, greatly exacerbates these delays.

The problem to me seems to be the attempt to run a timetable service clashing with what the public really want - a service every ten minutes. Buses run late then rush to catch up and buses behind the late running buses soon have their nose right under the tail of the late bus. I need hardly say this a source of huge irritation to individual passengers and brings great contempt upon urban bus systems everywhere, doubtlessly losing millions of passengers every year world-wide.


Australian based International public transport consultant Jarrett Walker writing in his blog  "Human Transit" last year defined the conflict between timetable and achieving consistent headway,  the sort of contradiction that Metro has yet to address well if it wants to create quality bus services.

But once a line is running better than every 10 minutes, no customer is waiting specifically for the 5:32 as opposed to the 5:35 trip, so the on-time performance of that trip doesn't matter.  What matters to the customer is the actual waiting time.

For a simple model of why this matters, imagine that you have a bus line running every 10 minutes, and every single bus is exactly 10 minutes late.  From the standpoint of a classic on-time performance measure (which typically counts the percentage of trips that are more than five minutes late) this situation would be described as 100% failure, because 100% of all trips are late.  From the customer's standpoint, on the other hand, this would be perfection: buses are coming every 10 minutes, exactly as promised.  

With the sort of infrastructure that 21st century public transport can have, should have and in some cities does have - including GPS, remote signals, and a computerised central control room, and staff facilities on route at a transfer station, The Orbiter could operate fully as a holistic system. In an integrated system a computerised map, virtually a clock face would show where buses were and signals (either directly to the bus or to roadside signal points) would indicate for buses to slow down or speed up, within the operating margins of the law.   A large circular system like The Orbiter should include a stand by bus at a central point that can access the route in either direction from multiple points, so in the event of serious delays an extra bus can be inserted and another phased out at a set point, according to a publicly recognised protocol. 

Strangely enough - quite counter intuitive - it seems to me a circular system such as The Orbiter would best maintain even 10 minute headways - run on time (so to speak) not for the most part by buses speeding up but by buses slowing down !  When a bus running "on time" is running ahead of a bus running behind time, and the bus behind the bus running late catches up everybody loses out.  A departure time pattern of  three buses evenly in succession 20 30 40 can become 20, 38 (running eight minutes late) and 40 giving an 18 minute wait for those arriving at the stop just as the 20 minutes the hour pulls away.  A holistic system by comparison has elasticity and the 20 past the hour and the following couple of services drop back, a few minutes each temporarily, while he 40 past drops back a whole 5 minutes, This in turn allows the bus 8 minute late to catch up three minutes (because it is picking up less passengers), by ten minutes journey down the road the pattern should look 30,40,50 (and 00 10 etc) but is actually 33, 45 57 09  20 etc....achieving a set goal of no wait greater than 12 minutes, subsequently allowing the system to re-establish stable consistent 10 minute headways.  Under a monitored central control room situation such adjustment and fine turning would be the norm, a constant fine tuning to get 21st century quality service.

Although complicated on paper it is no more than the skills required of air traffic or railway shunting yards, a combination of technology and and learned and honed skills of assessment and judgment, no doubt also able to factor in different congestion sticking points, expected passenger heavy loading points such as High Schools etc and recognise when inserting a stand-by extra bus is required. I imagine at times high stress but immensely satisfying too, once skills are honed by suitably adept persons - and of course part of complete network wide mapping and tracking. Overseas giving bus systems the same sort of infrastructure support as traditionally given rail is showing buses can out-perform rail by almost every criteria, including cost-effectiveness, and can be superior in almost every category to rail except moving very very large numbers of people all traveling in the same direction over longer journeys (definitely not the Christchurch situation). 

Even in the days before computers city bus systems often had timekeepers on corners, indicating by hand signals for buses on shared routes to "speed up or (more likely) slow down". It is sad that Metro can not achieve even this level of technology, 50-70 years old!

A trendy space age name The Orbiter rings a bit hollow, when photos like those above are so often so easy to take. Christchurch has a very long way to go if it wants to get 21st century quality bus services!!  

Space travel on "The Orbiter" - it's a strategy needed now more than ever.   







1 comment:

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