Trolleybuses are an integral part of the Wellington bus service. They are operated by GOWellington, part of Infratil's NZ Bus, on behalf of Metlink, the brand name of Greater Wellington Regional Council's public transport network. There are 60 trolleybuses in operation — most of the current fleet was built in the 1980s, being replaced by new vehicles.
Trolleybuses serve the southern, western, and eastern parts of Wellington City.
1 Wellington Railway Station-Island Bay
2 Wellington Railway Station-Miramar
3 Karori Park-Lyall Bay
5 Wellington Railway Station-Hataitai 6 Wellington Railway Station-Lyall Bay
7 Wellington Railway Station-Kingston
9 Wellington Railway Station-Aro St
10 Wellington Railway Station-Newtown Park Zoo
11 Wellington Railway Station-Seatoun
Routes operate all day every day, except 5 and 6 (Monday-Friday peak hours only), 9 and 10 (Monday-Friday only, not evenings). Evening and weekend services are usually operated by diesel buses.
The main city-centre trolleybus corridor is along the Golden Mile from Wellington Railway Station (terminus of all routes except the 3) via Lambton Quay and Willis St (served by all routes) to Courtenay Place (served by routes 1, 2, 3, 5 and 6).
To the south-west, routes 7 and 9 run along Willis St (northbound), Victoria St (southbound) before splitting — the 9 runs west up the Aro Valley, the 7 climbs the hill southwards to Brooklyn, Mornington and Kingston.
To the south, two routes run to Newtown (10 and 11 via Taranaki St, 1 and 3 via the Basin Reserve), with the 1 continuing south to Island Bay, the 10 terminating at Wellington Zoo, and the 3 and 11 turning east to Kilbirnie, where they meet routes 2 and 6 via Hataitai (where route 5 has a large terminal loop). From Kilbirnie routes 3 and 6 run south to Lyall Bay, the 2 and 11 east to Hobart St: the 11 continues east to Seatoun and the 2 heads north to Miramar.
A second and more extensive trolleybus system was approved in 1945, when it was decided to gradually replace the city's trams with trolleybuses. Trolleybuses were preferred over trams for being more manoeuverable and "more modern", and were preferred over diesel or petrol buses due to better traction on steep slopes.
At its maximum extent the trolleybus network stretched for around 50 kilometres — in addition to current services, trolleybuses also went to Oriental Bay, Northland and Wadestown, and routes in the central city were more extensive. The trolleybus fleet peaked at 119 vehicles, including Crossley Empire, British United Traction RETB1 (in various forms) and Volvo B10M and B58 models.
The trolleybus system has been threatened with closure over the years, mainly on grounds of cost. The growing emphasis on environmentally-friendly transport has however prompted campaigns to keep the buses, and in 2007 it was announced that a new generation of trolleybuses would be funded. The new buses are being built by Designline in Ashburton, using some components from the current fleet. They have a greater passenger capacity than current buses, and incorporate other improvements — they are expected to de-wire less frequently, and will be able to operate for short distances off-wire from batteries. Delivery of the buses began in late 2007.