Why not Bus Rapid Transit?
Gls(BRT) was chosen in Greater Wellington's gls(PTSS) (in preference to light rail), but was never implemented, and Wellington's golden mile bus route is still badly overloaded.
A BRT line has about one stop for every 3 regular bus stops. BRT and regular buses cannot both run on the golden mile, because there is no room for the faster BRT vehicles to overtake the slower buses. The only solution is another route but Wellington has few options; this dilemma is the primary reason why Wellington needs light rail.
The options for running BRT are:
* on a dedicated rapid transit corridor, such as the route gls(FIT) has proposed for light rail
* on a corridor shared with regular buses, which requires 4 lanes, so BRT vehicles can pass regular buses stopped at bus stops
In the city centre, once the Golden mile is eliminated as too narrow, this leaves:
* Waterfront (Jervois and Waterloo Quays), two traffic lanes become dedicated rapid bus lanes; or
* The Terrace, using Courtenay Place, Taranaki St, Ghuznee St, The Terrace and Bowen St, removing parking so BRT vehicles have room to overtake regular buses; the route is less inconvenient than it seems as many buildings on Lambton Quay have public access lifts.
Understanding BRT means recognising several varieties.
The first is ''almost-BRT'' that operates more as an express bus service on regular streets. A Terrace route would deliver an almost-BRT service. It could be implemented quickly and at relatively low cost, ''provided that'' parking spaces are removed to make room for BRT stops and so BRT vehicles can pass regular buses at bus stops.
''Almost-BRT'' could be a cost-effective stop-gap solution while a real rapid transit service is designed and built.
The second is ''BRT-lite'' operating on a dedicated 2-lane corridor, such as FIT's proposed light rail route. It would be limited to about 30–40 buses an hour. A double-articulated bus has a capacity of about 180 people, compared with about 470 on a much longer modern gls(LRV). Hence the capacity of BRT-lite is about half that of a 2-lane light rail corridor and Wellington would soon run out of capacity.
Adding a second almost-BRT route through the city via The Terrace would work for a while, but would soon become congested with continuing ridership growth. At that point a much larger problem would appear: how to find space for light rail construction?
''BRT-lite'' is impractical as a long term solution in Wellington.
''Full-BRT'' has similar capacity to light rail (say 10,000 passengers an hour), but in Wellington it would be very disruptive because of the width needed. Full-BRT has to run more frequently: say a LRV every two and a half minutes, but a bus every minute.
Full-BRT needs careful route-design: the ITDP 'Gold' or 'Silver' Standard. This will need:
* Longer and wider stops, to accommodate longer buses in three-berth stops, and much wider to allow overtaking at stops. BRT stops in Brisbane are nearly twice the total width of Manners St.
* More grade-separation at busy junctions. FIT anticipates one or two grade-separated junctions for light rail, and more for more-frequent full-BRT.
* Much more costly tunnels than light rail, because of larger cross-sections and services too frequent for a single-lane tunnel.
* A more difficult route, because full-BRT would be impractical on many parts of the corridor due to lack of road space.
* Greater operating costs because full-BRT would need more drivers, the greatest single cost.
''Full-BRT'' is very unlikely to be cost-effective in Wellington.