Personal Rapid Transit

Personal Rapid Transit ( PRT) is a concept of a leaderless, track guided passenger transport system that brings passengers without schedule individually to order without intermediate stops automatically to their destination.

Shuts it as primary care in public passenger transport ( public transport ), it is similar to a ring and ride a special form of public transport is, it drives like a privately owned taxi, then it is counted as private transport.

Term

In Germany the term " taxi cab " was since the fifties instead PRT initially used was in accordance with a specific project and Cabin taxi (see below). However, since there were no other projects of this kind, has prevailed in traffic science, the U.S. concept of PRT since the nineties. Other names are " PAT " (Personal Automated Transport ) and " podcar ". The word " staff " in PRT sets itself apart from the word " Mass" in Mass Transit ( public transit, public transport) from and says "personal" in the sense of "individual". However, the system as such is not a part from the perspective of traffic science to travel but for public transport.

Description

Unlike other fully automated, public transport systems, the passenger gets into small cabins to be self-determined goal. He need not to be based on a schedule, so use some PRT manufacturers the slogan: "Do not wait for the vehicle (or company name), but it is waiting for you ." In reality, this situation is of course a function of the load of the system. In contrast to the normal public transport is actually the possibility that wait the cabins like a taxi queue at a local under -load station. In a wide- developed network, a passenger can hit any target at a bus stop at any time. Does the PRT than public transport these criteria, it is considered one of the public transport special shapes and is due to an energy-saving drive technology an environmentally friendly alternative to the private car dar.

The energy consumption is due to the lighter in proportion to passenger cabins and the master control system which optimizes the flow of traffic, lower. In the track-guided PRT systems no combustion engines are used, all current systems are driven by linear or rotary electric motors. Power is supplied via sliding contacts or change batteries, or the cab drive is passive ( linear stator to the cabin, su Vectus ).

Depending on the system drive the cars with maximum speeds of between about 35 and 50 km / h The resulting lower mechanical safety precautions allow in contrast to passenger a smaller and lighter design. The speed is determined by the safety distance to the predecessor cabin in the column drive.

The safety you shall use the so-called brickwall criterion. It is here assumed that all of a sudden at a column ride in the worst case, the predecessor and immediately stops (infinite deceleration, as the lead cabin on a wall ). In this case, the successor to have sufficient distance in order to get maximum speed collision to a halt. In the 70s there were concepts that seek a coupling of the vehicles while driving, since just before the coupling of the distance is very small, the risk of collision in the brickwall criterion is too high. The spread of the brickwall criterion is derived from the braking distance and is therefore in the 2nd power (square) of the velocity. The throughput of the cabins per time thus has a calculated maximum. The maximum velocity is given by (multiplied by the actual distance ) from the maximum throughput, it is about 40 km / h If one were to increase the speed above this maximum, would increase with eingehaltenem safety criterion of distance so that the throughput, ie, reduces the transport capacity. If several cabins solid ( insoluble while driving) coupled together to form a train, the throughput increases approximately ( minus the cabin length) linearly with the number of cabins. The average effective travel speed ( Door to Door) in a big city is generally less than 30 km / h This is true both for public transport and for private transport.

The capacity, ie the persons carried per time, a path in one direction is calculated from the throughput of the cabins, multiplied by an assumed number of occupants. This value is hotly debated because it is measured by conventional public transport. For example, enter the Berlin S -Bahn trains at a maximum capacity of 36,000 people per hour, while a PRT value can hardly be achieved by 5000. The fastest PRT ( Vectus ) with a cabin throughput of 1200 indicated cabins would purely theoretical, ie with full four cabins, a capacity of 4800 people per hour. Certainly will not always fill in the rush hours in direct trips from the periphery with a plurality of stations in the city center of the crowds.

At this point the differences to the public transport significantly. When the trains arrive with high capacity in the periphery, drives the ton train which can accommodate about 1000 people, often empty until the last station. This is excluded in the PRT if empty trips in one direction are necessary in the " rush hour ", because at least one direction is approached demand-driven.

The number of passengers per cabin varies between one and about twelve. For smaller networks, test equipment, with a few stops the requirements of individual are not adequately met. To ensure that transport services anyway, one is forced in the introduction of pilot plants operating in the public to make the cabin for a large number of people, which in turn reduces the attractiveness and contrary to the actual principle of the PRT. Therefore one speaks with automated ( driverless ) system from twelve occupants of a so-called People Mover; Similarities with the Marschrutka then come to mind.

Past projects

To this day, numerous systems have been tried with very different technology and built. This project was supported by Richard Nixon as a demonstration project for a modern urban transport and was built in the time of the first oil crisis in 1974 and taken after a year in operation. The relatively large cabins for 12 passengers and in proportion to the length of the network of 14 km small number of five stations reduces the individual character of the system, so you might already be almost described as a people mover. Moreover, the system works depending on time of day in two modes: firstly as People Mover posted at each station keeping, clocked at scheduled times, and on the other in the PRT mode to order directly to the destination.

One of the first large PRT projects named Cabin taxi was tested with a 1.5 -km-long circular route also in 1974 in Hagen (NRW ), which was, however, set back in the early 1980s.

Developed in France and tested the Matra 1973-1987, the PRT system Aramis. There were several experimental facilities, first at Paris- Orly airport and later on Boulevard Victor in Paris. Aramis consisted initially of four-seater cabins with rubber tires that have been driven by a rotary electric motor. Particularly innovative was the intangible or electronic coupling, brought together by the single cabins, train parts, but could be separated at fork in the road at all times. Due to technical difficulties, as well as by disagreement among the project partners, the original Aramis concept was so strong modified so that it resembled more and more conventional transport systems. Finally, the cabins should take up to 20 people and two cars are mechanically coupled to each other. 1987 Aramis was shelved for lack of funds and shut down the test facility on Boulevard Victor.

In the 90s, the American company Raytheon has invested heavily in the development of a PRT system called PRT2000 with similar-sized cabins, but failed in a bid for the construction of a system in Illinois, near Chicago, as the cost of $ 50 million per mile exceeded.

Current Projects

At London Heathrow Airport Terminal 5 in late 2010 was taken as a pilot project in operation, the first commercial manufacturer ATS Ltd named ULTra of the BAA plc PRT system. The construction of the routes were completed in October 2008. In the first experimental phase initially to 18 cabins are used. In a cabin fit four adults and their luggage. The PRT transported the passengers of a more distant long-term parking to its terminal after they have entered their flight number. The battery-powered vehicles are designed for a distance of 4 km. If the pilot project is successful, it will be extended to the entire airport and surrounding hotels with 400 rooms. It is the year 2010, the first commercial PRT system in the world.

In terms of political commitment Sweden has taken the lead. Here a network of interested municipalities has called " Compass " pushed the issue far. A comprehensive study of the Ministry of Infrastructure has been in cooperation with Banverket, the Swedish Rail Administration, and other institutions go-ahead for pilot plants for public use in selected cities. In Uppsala (Sweden) a run with linear motors PRT system has already been tested. The system, named Vectus PRT, a subsidiary of the Korean Stahlunternemens POSCO, the first rail-bound system that has been tested successfully with modern safety requirements.

POSCO has with the city of Suncheon City (about 20 km of the main plant of POSCO away ) signed an agreement in September '09, and indeed for the construction of a PRT network with a route length of first 5 km and 40 Podcars. In 2013 the city hosts the International Garden Expo, which will be located in a conservation area, the Wetland Park. According to the mayor, all visitors would currently (indicated by 3 million / a ) visit the park by car. Through the PRT system, the parking lot should be moved into the country.

The largest planned PRT network whose pilot project is already under construction, comprises 33.1 km path length and is hit with 2500 cabins 83 stations. The cabins of the Dutch company 2getthere, called " pods" are supplied with lithium iron phosphate battery. It is installed in Masdar, a green city, and in other parts of the city of Abu Dhabi in the United Arab Emirates.

The University of Paderborn explores a large taxi called RailCab on the railway network.

Criticism

Also arise at PRT congestion when the capacity limit is reached. The advantage is that it is easier to optimize the flow of traffic, as it has a more direct influence on the vehicles. One can safely assert that one person per PRT cabin capacity per track may not be much greater than for passenger cars, and this is above all because in the real urban car traffic safety distances are normally undershot strong. For safety reasons, such short distances are not feasible in a fully automated, driverless system. However, this also means a higher systemic safety of PRT. Current systems that are in operation, have, due to the immature regulating the distance a so-called " Headway " greater than 6 s, which limits the capacity prevail.

If a stop to the " Rush Hour" overloaded and busy all the holding tracks so the stop can not be approached. Either the vehicle waiting and blocking the lane, or it continues, and the passengers who were trying to get out will be further promoted by force.

PRT systems reduce the required number of parking spaces, but less the required number of vehicles ( in service ) or tracks to reach the same maximum transport capacity of existing as individual traffic. However, one can say that a much smaller area and energy consumption can be achieved by optimized for passenger transport types of cabins.

The required area can be further reduced by a spiked line, which, however, unlike in the photomontage of Spårtaxi, in reality, represent much more massive and thus achieves a lower acceptance of the cityscape.

One advantage is that vehicles that are used by commuters in the morning and evening, standing around not parked in the other time, but others can be used as transportation.

Documents

( more ) PRT projects

• CityMobil