thumb|Cabinentaxi test track in Hagen, Germany, in 1978
Cabinentaxi, sometimes Cabintaxi in English, was a German people mover development project undertaken by Demag and Messerschmitt-Bölkow-Blohm with funding and support from the Bundesministerium für Forschung und Technologie (BMFT, the German Ministry of Research and Development). Cabinentaxi was designed to offer low-cost mass transit services where conventional systems, like a metro, would be too expensive to deploy due to low ridership or high capital costs.
Cabinentaxi systems could be operated in a variety of fashions depending on the need. It is most widely known as the first true personal rapid transit (PRT) system, where customers call up a small "car" on demand which then takes them directly to their destination without any stops along the way. The system could also be used in a group rapid transit (GRT) fashion, using larger cars with up to 18 passengers. In this case the vehicles would travel along a fixed route, stopping at any station that a passenger requested. Cabinentaxi could also mix the two modes on a single line, which allowed direct routing to high-density areas when traffic loads were low, saving the larger van-like vehicles for the high-demand periods.
Cabinentaxi was in serious consideration for two deployments in the late 1970s; BMFT was in the process of funding a deployment in Hamburg while their U.S. counterpart, the Urban Mass Transit Authority (UMTA), selected it as a front-runner for a deployment in Detroit. Cabinentaxi's corporate partners decided to pull out of the Detroit competition to focus on the Hamburg development. When unrelated budget cuts drained the BMFT's coffers, the Hamburg project was also canceled, and the Cabintaxi Joint Venture gave up on the public transit field and withdrew the Cabintaxi technology from the market. The rights were purchased in 1985 by a small U.S. consortium, Cabintaxi Corporation, but no developments have followed. The only commercial use was a modified system, the Cabinlift, which operated as a horizontal elevator between buildings at the Schwalmstadt-Ziegenhain hospital in Germany until 2002.
History
Background
In the early 1950s, urban planner Donn Fichter started work on a book that would eventually emerge in 1964 as Individualized Automatic Transit and the City. Fitcher argued that the only way to solve the gridlock problems in cities being caused by increased car ownership was to use mass transit systems. Fichter argued that unless the systems operated more like a taxi service, arriving when called for and taking the passenger directly to their destination, people would not leave their cars to use it. Busses and metro systems are not personalized, they run on pre-planned routes and schedules, making stops along the way that do not serve each individual, only the group of riders as a whole.
Fichter and other planners tapped into a zeitgeist that was being fuelled by rapid urban decay in the U.S. President Kennedy addressed congress in 1962 and stated that "To conserve and enhance values in existing urban areas is essential. But at least as important are steps to promote economic efficiency and livability in areas of future development. Our national welfare therefore requires the provision of good urban transportation, with the properly balanced use of private vehicles and modern mass transport to help shape as well as serve urban growth." Funding provided through the U.S. Department of Housing and Urban Development (HUD) led to a series of reports by a variety of aerospace firms (notably Aerospace Corporation), today known as the "HUD reports", that explored various concepts and provided strong support for the basic concepts. A follow-on bill later in the decade provided additional funding for development of several experimental systems, and created the Urban Mass Transit Administration (UMTA). At the time, the Bundesministerium für Forschung und Technologie (BMFT) was involved in a wide variety of transport research, including a variety of maglev trains for high-speed service, several automated railway systems, as well as more mundane research in railway safety and signalling. Significant within the transportation development programs of the BMFT was the direct involvement of the VOV (German Association of Public Transit Operators), the Deutsche Bundesbahn (German Federal Railway) and their safety experts. This assured that when development was completed, the systems would meet German (and by extension international) public transit standards.
When the BMFT learned of the separate efforts at Demag and MBB, they urged both companies to combine their efforts under a new joint operating company, which became Cabinentaxi. BMFT provided 80% of the total funding, considerably less than their counterparts in the U.S., which completely funded by the UMTA. By this time the system had been well-defined, and was committed to true PRT point-to-point service. In order to avoid stops along the way, stations were "off-line", on separate guideways placed beside the main routes, allowing en-route cars to pass them by. The cars themselves would handle switching along a pre-defined route, which allowed them to be directed to an optimal path in a network of any complexity. Studies suggested a three-passenger car for the basic system, although in order to increase capacity they also had cars with seating for 6, 12 and 18 passengers. These larger cars would normally be planned to operate in GRT fashion in order to increase the overall capacity of the network in the early development stages, where small networks in dense areas would not be meaningful in a small vehicle PRT mode. The larger cars could also be connected front-to-back to form two-car trains, further increasing capacity for some simple applications.
One problem with all elevated transportation system structures in general, is that the guideways (highways or transit) are widely considered to be an eyesore. In order to reduce the size of the guideways, Cabinentaxi took the uncommon approach of optionally allowing its cars to run on the top or bottom of a single track. The cars could not be switched from top to bottom, however. If this option was used, the guideways were supported on pillars that attached to the track from the side, rather than directly below. Cabinentaxi's guideway is noticeably smaller and thinner than conventional elevated systems, like the Vancouver SkyTrain. The track is approximately six feet wide, slightly smaller than a row of parking spots on the side of a city street.
Prototypes and testing
Testing of the motor and control systems started in 1972 on a 13-meter closed-loop track, running for 18 months. This was followed in August 1973 by a 150 meter test track and three 3-passenger vehicles installed near Hagen, Germany. The test track was expanded several times. By October 1974 it was 1136 meters long and featured two passenger stations with a closed-loop track, adding two additional vehicles for a total of five. By 1975 it had three stations and nine vehicles. The first 12-person vehicle was introduced that October. The final expansion was completed in 1976, bringing the total track to 1.9 km with six stations and twenty-four vehicles.
Deployment projects
When the safety studies were completed the various levels of government signed off on the system and released it for commercial development. Several developments were already being studied by that point.
One was an expansion of the original Hagen system, done as much as an example of the planning process as a serious proposal. This deployment envisioned a staged development starting with the 12-passenger cars in a network of about 40 stations covering the downtown core. Additional lines would then be added until it was fully expanded with 138 km of track and 182 stations covering the majority of the city and several surrounding suburbs and towns. The outlying tracks would primarily use the smaller cars. Funding for this deployment was not forthcoming.
A system was proposed for Hamburg, initially consisting of approximately 7.5 miles of over and under guideway with 11 stations and 50 vehicles. In 1977 Hamburger Hochbahn estimated the total costs for this initial installation to be $56,568,000, or $7.5 million per double lane mile (compare with a Canadian estimate from 1980 at $75 to $80 million per mile for underground subway lines). These were not the final system costs which would have only been determined after construction, and cost increases were already being experienced as the project neared the start of construction.
The developing firms found themselves without a market opportunity in Europe or the United States, and withdrew from the public transit field. Interest in the system in the U.S. lived on, and in 1985 a consortium was arranged to take over the design rights under Cabintaxi Corporation. No installations followed, however.
Design
Vehicles
The final primary vehicle designs for the Cabinentaxi system were the "KK 3"(Klein Kabine 3), a three-passenger vehicle, and the "KK 12" (Klein Kabine 12), a twelve-passenger vehicle, both with a semi-automatic doors. They were designed with enough room between the seats for wheelchairs, prams or bicycles. The doors were semi-automatic, locking and unlocking under vehicle control, but slid open by the passengers. The vehicle bodies were made of aluminum over a steel chassis, riding on solid rubber wheels that engaged the guidance rails in the track.
Cabinentaxi offered very high capacity utilization of its lines, up to 80% full before congestion would occur. Cabinentaxi also had a number of different car sizes, seating 6, 12 and 18 passengers. The larger cars could be formed into two-unit trains which could increase system capacity in small loop or shuttle operations, but the two-unit train had limited advantage in large network applications where short headways are effectively an electronic coupling. The "KK" series of vehicles, "KK 3", "KK 6", "KK 12", and "KK 18" (all designed, but only the KK 3 and KK 12 were developed), were all of the same cross-sectional area with only the length of the vehicle changed. With the same construction style in the body and undercarriages, these vehicle could share the same small vehicle guideway. As they have no moving parts, a LIM-powered vehicle would be more reliable than one using a conventional motor. Another advantage is that there is no contact between the motor and the track, so snow or rain will not affect its performance, which means a LIM vehicle does not require additional headspace in bad weather. Also, because the traction does not rely on friction, LIMs can climb much steeper grades. On the downside, LIMs require a "reaction rail" for the motor to push against, which increases capital costs slightly.
Guideway
Cabinentaxi was designed to allow top or bottom running of the vehicles, or both on one track.