Friday, August 05, 2011

Road transport's most civilised invention?

Safe, reliable and direct pedestrian access to transport stops is a more fundamental need than niceties like seats, shelters and real-time displays. The latter all improve the passenger experience but are of little use if access to the stop is difficult.

There are numerous ways to improve pedestrian access across roads. Their cost varies from negligible (for a zebra crossing) to many million (for an overpass). In between are treatments involving median strips or traffic lights. Their effectiveness (as measured in terms of average and maximum wait times) likewise varies. There are also trade-offs, mainly based on whether we prefer roads to maximise throughput of car traffic or facilitate access via a variety of modes.

The table below compares how well various access measures assist the passenger cross a road to reach a stop. Assessment criteria included waiting time, whether guaranteed access is provided (a roundabout or an unsignalised road that offers an indefinite stream of unbroken cars does not, for example) and cost.

While each method has its strengths and weaknesses, the humble zebra crossing stands out as the highest and best means of pedestrian access. They are also very cheap to build. I would go so far to nominate the zebra crossing as road transport’s most civisised invention.

How did I reach the three criteria?

Firstly access time. A critical part of making public transport more attractive is speeding random-arrival end-to-end travel times. Along with bus or tram priority, out of vehicle components of travel time are the easiest and cheapest to improve through attention to co-ordinated timetabling, service frequency, easier interchange and pedestrian access.

Then there’s the measure of whether guaranteed access is provided. This affects all walking trips but is particularly critical for access to public transport due to its reliance on timetables and the large time consequences (up to an hour) if a service is missed. Unlike signalised intersections, underpasses and zebra crossings, busy roundabouts or unsignalised intersections with continually flowing traffic offer no such guarantees so are major barriers to pedestrian movement.

Lastly there is cost, for which I make no apology in including. Especially in a dispersed city with thousands of intersections, a large number of low-cost improvements would probably benefit more people than a few very expensive projects. For example, 100 new zebra crossings may be possible for the cost of a single elaborate pedestrian bridge, while for motorists there are similar trade-offs between new road/rail grade seperations (cheaper) versus new bypasses or freeways (more expensive). Bus/tram priority at intersections and roundabout removals are similar low cost/high gain projects.

Zebra crossings have another virtue in that they only slow road traffic when used. Due to this and their low construction cost it is best to err on the side of too many zebra crossings than too few. And what some may see as too many assists walkability as it makes a neighbourhood more permeable on foot.

If a new crossing is so heavily used that motor traffic is significantly delayed, it should not be condemned. Rather it is evidence that it filled a previous unmet access need and has encouraged people to walk rather than drive for short trips. Most people are pragmatic rather than ideological in their transport choices, so an improvement in walking access should result in more walking.

Zebra crossings undoubtedly have their detractors.

Busy crossings may be seen as impediments to motorists, much like pedestrians see roundabouts, freeways and long ramps to overpasses. For they, along with traffic calming and even some road rules, challenge the doctrine of the ‘open road’, a presumptuous and romantic relic from early last century’s gentleman motorists and their clubs.

Mid last century’s ‘scientific’ traffic engineers also had little time for the zebra crossing due to their ‘inefficient’ obstruction of car traffic. Grade seperating various road users became the fashion. Trams were to be dismantled or buried, cars kept at level and pedestrians confined to overpasses in various proposals for central Melbourne (including from the RACV). 1950s futurist images often showed a fourth level; a swarm of commuters in helicopters.

While private motoring took off, mass grade seperations in our city centres did not. Costs were prohibitive. Road – road and road – rail seperations in established areas often cause overshadowing and urban blight, with Sunshine, Oakleigh and Huntingdale being prominent Melbourne examples.

The closing decades of the 1900s was marked by a reaction against the traffic engineer’s dominance of city planning. Examples include the 1970s freeway revolts and 1990s ‘new urbanism’ movements. Urban amenity was considered sufficiently important for the King Street bridge in Melbourne’s CBD to be removed and levelled, while pedestrian access to Southbank was improved as part if its redevelopment.

Environmental, security and physical benefits are often-cited advantages of more people walking more often. However in daily life these ‘warm and fuzzy’ factors are unlikely to influence behaviour beyond the minority who think strongly about these things.

Much greater success is likely if walking becomes attractive to the ‘transport pragmatists’ who will use whichever mode best suits the trip at hand. It is here that road transport’s most civilised invention may have benefits disproportionate to its small cost.

1 comment:

Riccardo said...

Peter, once again you've mentioned something Melbourne does badly but Sydney does not, and generalised that everyone does it badly, namely grade sepping.

Your typical Sydney sep in the last 50 years has been less like Oakleigh and more like Lyndhurst.

Sydney has not craved walk-up or rail-side shopping strips. You won't see 1-2 storey neglected shopping strips like at Oakleigh -you'll have 10-12 level apartment buildings walling the rail corridor like a canyon.

I've always regarded Sydney rail corridors as much more separated from the landform than equivalent Melbourne ones.

Look at Hughesdale for example, where the main railway to Bairnsdale (and once to Orbost, Woodside and Wonthaggi) squeezes in between a couple of single storey or double storey shop fronts, with a narrow Poath Rd and a side road.

Compare it with an equivalent stretch, say Allawah, with giant cuttings and embankments, stations with massive overhead concourses like Westall now has.

So no, grade sepping Melbourne style may be a failure and a bliught, but only in the Melbourne context.

You forget that Westall or Laverton style works have happened at Glass Hourse Mountains, for 10 trains a day, or the comprehensive disconnection of Cockburn Central from its surrounds.