The O-Bahn Busway is a guided busway that is part of the bus rapid transit system servicing the northeastern suburbs of Adelaide, South Australia. The original O-Bahn system is the one in the German city of Essen, and it was conceived by Daimler-Benz to enable buses to avoid traffic congestion by sharing tram tunnels.
Adelaide's O-Bahn was introduced in 1986 to service the city's rapidly expanding north-eastern suburbs, replacing an earlier plan for a tramway extension. The O-Bahn provides specially built track, combining elements of both bus and rail systems. The track is long and includes three interchanges at Klemzig, Paradise and Tea Tree Plaza. Interchanges allow buses to enter and exit the busway and to continue on suburban routes, avoiding the need for passengers to transfer to another bus to continue their journey. Buses can travel at a maximum speed of , but have been restricted to a speed limit since 2016. , the busway carried approximately 31,000 people per weekday. An additional section including a tunnel opened in 2017 at the city end to reduce the number of congested intersections buses must traverse to enter the Adelaide city centre.
The development of the O-Bahn busway led to the development of the Torrens Linear Park from a run-down urban drain into an attractive public open space. It has also triggered urban development around the north-eastern terminus at Modbury.
Track
The O-Bahn track is made of concrete; it is elevated from the ground because of the poor quality of alluvial soils along the River Torrens, which frequently move due to their high level of plasticity. On top of the pylons are concrete sleepers on which the track rests. 5,600 pylons were drilled in place to support 5,600 sleepers and 4,200 prefabricated L-shaped track pieces, sited at intervals. Concrete pylons were cast into the ground to ensure stability, to a depth of up to . The width of both tracks, sitting on the sleepers, is .Northeast Busway Project (Brochure). South Australian Department of Transport (1983).Busway Information, Paper Two: O-Bahn Guided Bus Concept. South Australian Department of Transport (1983). The O-Bahn's concrete tracks were narrower and lighter than those of the initially proposed light rail development, and put less stress on the land. The concrete components were precast and then laid onto piers.
At the city end, the O-Bahn begins at East Terrace, as an extension eastwards from Grenfell Street into the parklands. The O-Bahn enters a tunnel, completed in December 2017, which curves from east to north, emerging onto bus lanes in the middle of Hackney Road just north of the intersection with Botanic Road and North Terrace. The bus lane continues north to the River Torrens and into the original entrance of the O-Bahn on Hackney Road, opposite the East Parklands, where it enters a tunnel at a speed limited to , due to the tight initial corner, ensuring that the rear tyres (especially trailer tyres of articulated buses) do not 'scrub' against the track. Speed is gradually increased to for most of the trip to Klemzig Interchange. Once en route to Paradise Interchange, the speed limit was up to , but has been limited to since late 2012. On some sections was achieved in tests. The average service speed including stops is about . On entering interchanges the O-Bahn ends and the speed limit is . In the interchange area, the speed limit is . The O-Bahn is officially considered a road, due to a court ruling in the early years of the system's operation. This ruling permits the South Australia Police to install speed cameras and fine speeding drivers.
Cars entering the O-Bahn are deterred by a large number of signs at entrance points and a sump buster device that rips out a car's sump (oil pan) if it gets onto the track. An average of four cars per year enter the O-Bahn and must be removed by crane.
Buses
The first buses to enter service on the O-Bahn were 41 rigid and 51 articulated Mercedes-Benz O305s. These were modified for O-Bahn use by Mitsubishi Motors' Clovelly Park plant before being bodied by Pressed Metal Corporation South Australia.First production O-Bahn buses takes to longer track Australian Transport February 1985 page 13 The cost was included in the original $98 million budget. Modified MAN SG280s and SL202s were later purchased.
With the Mercedes-Benz O305s approaching their 25-year age limit, tenders were called in 2007 for replacements. The new buses were Scania K230UB rigid and Scania K320UA articulated buses bodied by Custom Coaches. , these, along with rigid Scania K280UB/K320UB buses, articulated Scania K360UA buses, one diesel/electric hybrid Scania K320UB, and one Mercedes-Benz O405NH make up the fleet.
In the case of breakdowns, a specially designed vehicle nicknamed 'Dumbo' is used to tow buses from the O-Bahn. In the early stages of design it was intended that all buses would have towing ability; however, this was soundly rejected by the drivers' union and 'Dumbo' was purchased. If a tyre blows during a trip the guide-wheel prevents the bus from erratic movement, and a smaller aluminium inner tyre allows the bus to be driven to the nearest station at .
The guide-wheel, which protrudes just ahead of the front wheels, is the most important part of the bus when travelling on the O-Bahn. It is connected directly to the steering mechanism, and steers the bus by running along the raised edge of the track. While it is not strictly necessary for drivers to hold the steering wheel when travelling on the O-Bahn because of the guide-wheel, safety procedures require the driver to be alert to their circumstances at all times. A rumble strip before stations is a reminder that they need to resume control. The guide-wheel is the most delicate part of the system and is designed to snap off upon sharp impact; before the O-Bahn was in place, a number of buses were fitted with guide-wheels for their ordinary routes to test their durability. Drivers were forced to be more cautious on their normal trips after numerous guide-wheel-to-kerb impacts.
Since June 2018, services are operated by Torrens Transit under contract to Adelaide Metro. , the busway carries approximately 31,000 people per weekday.
Interchanges
Klemzig Interchange is the first station, from the city centre in the suburb of Klemzig. It was built as a connector to the city loop 'Circle Line' bus service, which followed the Adelaide outer ring route. Many bus services bypass Klemzig and the station has limited capacity. It contains a park & ride carpark with 450 spaces.
Paradise Interchange is the second station, from the city centre, in the suburb of Paradise. The terminus before the completion of Stage 2, it is now served by buses from suburban streets, and has a total of 875 car parking spaces in two areas.
Tea Tree Plaza Interchange is the terminus, from the city centre, in Modbury. Adjacent to the Westfield Tea Tree Plaza, it is the largest O-Bahn station. Bus services from this interchange connect to areas as far away as Elizabeth and service the Golden Grove area. It has 700 car parking spaces, after a multiple level carpark was built during a redevelopment in 2013.
Route
Outbound O-Bahn bus routes travel through the Adelaide city centre along Grenfell Street, and enter the O-Bahn via the tunnel (opened on 10 December 2017) through the Adelaide Park Lands in Rymill Park. They then exit the tunnel on Hackney Road, north of the intersection with Dequetteville Terrace, and then proceed northwards along the road in designated bus lanes. Along this stretch the Adelaide Botanic Garden is on the left, followed by Botanic Park. Hackney Road—along with the designated O-Bahn bus lanes—crosses a bridge over the River Torrens, with the bus lanes veering easterly, to the northbound entrance of the guided O-Bahn busway. The busway dips below the surface road (Park Road) to join the inbound (southbound) track, both heading northeast.
The busway follows roughly the Torrens River valley, but with smoother curves. This means that it crosses the river quite often, with either a park or a few houses on a point surrounded by the river and busway. This occurs a total of eight times before the busway reaches Klemzig Interchange on the north side of the river. The busway crosses the river again soon after Klemzig and passes Lochiel Park and part of the suburbs of Campbelltown and Paradise to its north between the busway and the river before reaching Paradise Interchange.
After Paradise Interchange, the busway passes under Darley Road, then over the Torrens for the last time. The terrain becomes steeper as the busway proceeds up along the outflow creek and past the northwestern side of the Hope Valley Reservoir. It proceeds north under Grand Junction Road, then swings east and north again to enter the eastern side of the Westfield Tea Tree Plaza shopping centre precinct, where the guided busway ends at Tea Tree Plaza Interchange. Most buses continue on normal roads to service suburbs further afield.
All listed routes connect Adelaide City Centre to the named endpoint, but service different suburbs between the O-Bahn interchange and that endpoint.
History 1955–1980: Transportation planning and options
The greater Adelaide area experienced significant growth during and after World War II. Between 1944 and 1965, the area's population doubled,Greater Adelaide's population increased from 365,000 in 1944 to 748,000 in 1965. "Population Distribution". 3105.0.65.001 Australian Historical Population Statistics, 2014. Australian Bureau of Statistics. and the number of private motor vehicle registrations increased 43-fold. In 1955, the state government under Premier Sir Thomas Playford established a Town Planning Committee and commissioned a coordinated plan to guide the future development of Adelaide. The resulting 300-page study, "Report on the Metropolitan Area of Adelaide 1962", laid out a 30-year development plan, including a proposed of improved roadways. Shortly before leaving office in 1965, Playford commissioned a detailed study focusing on the recommended transportation improvements.
In 1968, the government received the Metropolitan Adelaide Transport Study (MATS) that envisaged a network of 10 freeways crossing the metropolitan area, a rapid rail network, and an underground city loop railway. MATS drew massive public opposition, as it called for the acquisition of thousands of properties and would effectively supplant a number of suburbs that were to become the sites of interchanges. Arguments broke out in Parliament, and widespread images of gridlock in overseas freeway networks contributed to the furore. Nonetheless, in early 1969 Premier Steele Hall approved implementation of the plan in a modified format, and the government began to purchase property along the proposed corridors. In mid-1969, faced with ongoing opposition, the state abandoned plans for 2 of the 10 proposed freeways. Hall was voted out of office in 1970, and the new government under Premier Don Dunstan passed a 10-year moratorium on freeway development, effectively shelving MATS. The already-acquired corridors were retained for potential future use.