Spine Study Problems
Kerry Wood

Wellington’s most important public transport study in years came out on 18 June. Sadly, it is a damp squib.

The Public Transport Spine Study made a good start. All options were taken seriously and whittled down to three, all workable: bus priority, a busway or a tramway.

The Terms of Reference use the phrase “high quality public transport” 16 times. Studies called for, and their outcomes, include:

• A range of route options. The existing main bus route, plus an already-rejected waterfront option (re-rejected) and some perverse options for an extension to Kilbirnie.

• Good alignment with WCC’s proposed development spine (for inner-city housing), from Kilbirnie to Te Aro. A route mostly at the edge of the development area, plus Mt Victoria tunnel options totally ignoring the development area.

• A review of the interdependence between land use and transport infrastructure, and their interaction. Nothing.

High quality was slowly compromised away.

The bus priority option ignored a well-known rule, confirmed in the Bus Review study: no more than 60 buses an hour on a single lane. In November 2012 officials called this an ‘aspirational target’ (Report 12.497), despite an excellent explanation in the Bus Review. It isn’t aspirational and the bus priority proposal will solve nothing.

Bus Rapid Transit—a busway—can carry well over 60 buses an hour, more than enough for Wellington, and all on two traffic lanes. So far so good, but for the traffic proposed there are minimum requirements, ignored in the Spine Study:

• Most or all stops must have overtaking lanes for buses, in both directions.

• Busy road junctions must be grade-separated: a flyover or underpass. Minor junctions need traffic signals, with plenty of green-signal time for the bus route.

A busway lacking these features will be little different from the existing buses. It will jam up in much the same way, about equally often. The US-based Institution for Transportation and Development Policy has a scoring system for busways, with gold, silver and bronze ratings. GWRC’s proposal would fail minimum requirements; In ITDP terms it isn’t a busway at all.

Now for the punch-line. Retrofitting a quality busway is impractical on the chosen route. Brisbane has a good busway, with stops about 27 metres wide and at least four buses long. Such a stop would need the whole width of Manners Street for buses alone, with passenger and pedestrian space recessed into buildings. Te Aro Park is too short to be an alternative, and Willis Street too narrow. On the existing route there is no space for Brisbane-style stops between Brandon and Tory Streets. Something smaller might be practical in Wellington, or northbound and southbound stops might be staggered. The width a little better at say 18 metres, but length would be problematical.

Almost all junctions on the Brisbane busway are grade separated, which is why nearly four kilometres of busway is in tunnel. In Wellington, most junctions along Lambton Quay can probably avoid grade separation (subject to modelling checks) but an obvious exception is Whitmore Street. A busway underpass is impractical—it is in the tsunami zone—so that means a flyover outside Parliament Buildings, the Supreme Court and the Law School. Other likely flyovers include Taranaki Street and Vivian Street. But not the Basin Reserve; grade separation there is impractical, with difficult ground below and a prior claim above.

At this stage a busway is a high-risk choice. It would be a pity to spend $200 million on a busway, only to find light rail was needed anyway.

The Spine Study has overpriced light rail, at $NZ87 million a kilometre, when a typical system in the USA costs $NZ25 million a kilometre (range $10–75 million, data from Wikipedia). The Spine Study price difference between light rail and busway also looks suspicious. Realistic, comparable, cost-effective busway and tramway options should be much closer than this.

• Removing a totally unnecessary tram-only Mt Victoria Tunnel will bring the per-kilometre cost down to $52 million, the capital cost from $940 million to $560 million.

• A shorter and better light rail route, serving both Wellington Hospital and Kilbirnie, could save four route kilometres, bringing the capital cost down to $350 million.

• A busway capable of carrying much over 60 buses an hour will face additional costs for stops and route. It might be forced onto a waterfront route with stops above the existing traffic.

The best choice is probably the system that can most successfully negotiate the inner-city pinch-point, say between Brandon and Taranaki Streets. The Spine Study has assumed that the present layout is already the best option, fully adequate for all cases. The final choice will need provision for either busway or tramway, as well as some other buses. It may need four lanes for public transport. It will need to manage more restricted provision for motor vehicles. Good provision for walking and cycling is another must.

Kerry Wood is a retired engineer with a long-standing interest in transport matters.

ENDS

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