Low-floor technology

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Low-floor bus MB O 405 N2

Low-floor technology describes the design of vehicles , especially those used in local public transport, with particularly deep floors (or corridors) in the interior. This will make it easier for some of the passengers with disabilities or age-related mobility restrictions and with vehicles such as wheelchairs and prams to use them without barriers . Another advantage is the shorter passenger switching times .

In a broader sense, the term is used to describe the technology of car transport wagons (low-floor wagons) tailored to the special needs of the Rolling Road, with lanes running across the entire train and with small wheel diameters.

designation

The designation low-floor technology distinguishes this increasingly widespread standard from the construction method used earlier and still today in long-distance vehicles, in which the interior floors were largely installed with a simple construction above the vehicle chassis , with inevitably several steps at the entrance due to the high level had to be overcome - at least if there were no elevated platforms .

Executions

Lack of space: Part of the engine at the rear left in the passenger compartment (here a model by Neoplan, manufactured in 1986)

The low-floor construction is achieved with different structural measures depending on the vehicle manufacturer and vehicle type. With a more elaborate design, the vehicle floors are generally arranged lower and "suspended" between the axles, or the floor height is lowered with smaller wheels and shallower drives. However, the low floor height can often not be implemented in the entire area of ​​a vehicle, so transitions to articulated car parts in particular can only be lowered to a limited extent in order to preserve the space required for the couplings and drives at the ends of the car. In many cases, therefore, the low-floor construction is mainly carried out in the middle part of the vehicles and on the front side of buses, while the rear section and the transitions often have sloping surfaces or steps.

The low-floor technology requires the use of as compact as possible drive units , or at least other arrangements of the drive systems and auxiliary systems, such. B. in the bus - engine rear transverse to the direction instead of standing at rear. Starter batteries , tanks, electrical and compressed air systems can be housed in boxes under the passenger seats or roof ducts. As a rule, special designs are also required to drive the vehicles, such as deeply lowered portal axles with lateral differential gears in order to achieve a stepless vehicle floor in the rear area as well. In addition, buses can be pneumatically lowered on the entry side ( kneeling ). In connection with so-called high curbs at the bus stops, entry is made almost at ground level. The vehicles can also be equipped with ramps or lift systems for wheelchair users.

For cost and maintenance reasons, the transport companies have recently resorted to so-called low-entry buses , which are only partially built with low floors, or low-floor buses with an upright tower engine ( see illustration ), which means that the floor area can largely be realized without platform steps or steep inclines .

Articulated trams , which were previously mostly equipped with Jakobs bogies , required new concepts for the suspension of the wheels and axles. Due to the lack of space under the vehicle floor , the complete electrical control is located on the roof, which increases the demands on stability the body represents.

A further development of low-floor technology is the Niederstflurtechnik ( Ultra Low Floor ), in particular at tramcar is used.

history

Tram vehicles

Beginnings

Railcar of the Budapest Földalatti from 1896
Stepless car introduced in New York in 1912
London double-decker coach built in 1930 with low-floor entry on the lower deck
A Prague Krasin sidecar

The world's first low-floor wagon was created for the Viennese horse-drawn railway in 1891 . From 1896 , low-floor wagons also operated on the Földalatti , the first line of the Metró Budapest known today as M1 . Unlike the later built trails is as Unterpflasterbahn carried out with a particularly low tunnel height of only 2.85 meters, because of the route is a waste water collection channel. For this purpose, low four-axle vehicles were constructed, the floor of which was lowered between the bogies by floor frames with long girders cranked at both ends of the car. One consequence of this design, however, was that only the space between the bogies could be used as a passenger compartment. The driver's cabs were located above the bogies .

The first low-floor trams ready for series production were built in 1911 for New York Railways Co. , which purchased 176 such stepless cars within a short period of time and completely converted the route on Broadway in New York to low-floor operation. In Germany , the first three low-floor sidecars were delivered to the Bonn – Godesberg – Mehlem tram in 1914 . The Vienna tram received two double-decker prototypes of the F series in 1914. In order to save height for the upper deck, the lower deck had a low-floor design. The entry height there was only 190 millimeters above the top of the rail.

A low-floor car built in 1923 was delivered in 1924 by the Uerdingen wagon factory to the Frankfurter Lokalbahn , which used it on the overland routes to Oberursel and Bad Homburg . From the manufacturer's point of view, the vehicle was supposed to generate new orders, but remained a one-off and was decommissioned in 1954. It is now in the Frankfurt Transport Museum .

In 1925, the Great Leipzig tram ordered a central entry test train each from the manufacturers WUMAG Görlitz and Christoph & Unmack from Niesky, consisting of a two-axle multiple unit and two also two-axle sidecars. For the first time in Leipzig, the wagons were given an axle base of 3600 millimeters with a very flat bogie in between. This enabled the entry platform between the wheel sets to be lowered to 400 millimeters above the top edge of the rails despite the two-stage suspension. The two passenger compartments were accessible from the central platform via a further step. Because of the comparatively long wheelbase, the wheelsets were given Peckhampendel. While the WUMAG wagons were given solid floor frames in the shape of a fish belly and wooden wagon bodies attached to them, the Niskyer wagon bodies were all-steel constructions with a significantly more filigree appearance. This design was adopted for the 100 series sidecars. They were delivered in 1928 and remained in service until the 1970s. The wagons that were run by the Leipzig Transport Authority as Type 61 because their design did not allow the installation of magnetic rail brakes were retired between 1972 and 1975.

A little later, the Prague tram and the Bucharest tram procured very similar sidecars in larger series . From 1930 to 1946 Ringhoffer delivered 280 low-floor center entry cars to the Czech capital, which later became known as Krasin . However, this only later emerged with the series from 3005 to 3068 also suitable railcars, as mover carriage . In the Romanian capital, the main workshop itself produced such sidecars in 1929 and 1930.

The Süddeutsche Eisenbahn-Gesellschaft carried out further attempts in the direction of low-floor trams in 1926 on its lines, which today belong to the Essener Verkehrs-AG . These attempts were initiated by the manager of the Essen company, Walter Prasse . The vehicles, developed together with the supplier Gastell from Mainz , had a floor of 740 millimeters, which was low for the time. They also had middle entrances, which was also a rarity in those days. 25 railcars and 40 sidecars were produced according to this model. In 1930, the Czechoslovak engineer Eugen-Widolt de Montrose-Oster was hired as a consultant at SEG. This commitment turned out to be a stroke of luck.

Together with him and the Orenstein & Koppel company , the so-called bathtub on wheels was developed in 1932 . With this two-axle loose wheel wagon with a long wheelbase and independent wheel suspension, test drives were initially carried out in the city of Essen in order to find out the suitability of the drive for everyday use. The steering racks were initially left open in order to study their running behavior. In 1933 the testing phase was completed and a modern car body was ordered for the test vehicle. In June 1934 the car was presented to the public. Until 1943 it was usually used on the route between Alfredusbad and Gelsenkirchen-Horst . On March 5th that year the car was destroyed in an air raid.

After the Second World War

After a long break, the use of low-floor cars began again in 1985 on the Turin tram , where Fiat presented the first low-floor articulated car with the conversion prototype 2800. This was a partially lowered three-part six-axle vehicle with a floor height of 340 millimeters in the middle area. The low-floor area comprised around 70 percent; all four entrances were also located in this area. The Jakobs bogie of the two-part donor wagon was replaced by a short two-axle middle part on which both the front and the rear half of the wagon were supported. The car was in service until 2000.

The first series-produced low-floor wagons received the Geneva tram from 1987 with the 22 six-axle Be 4/6 series from Düwag and Vevey . In contrast to the Turin prototype 2800, the Geneva DAV trams are two-part and asymmetrical, with a front end with a bogie attached to a four-axle rear end. Despite the new - especially small - running wheels in the lowered area of ​​the rear section, the floor height in the middle section is still 480 millimeters - which is actually a middle floor car . Therefore an additional step in the interior has to be overcome when entering. The twelve eight-axle 731-742 of the Be 4/8 type for the Bern tram were built in 1989/90 according to the same concept ; they also have a step in the interior.

Continuously low-floor trams were first manufactured by MAN in 1989 for the Bremen tram . These first cars of the GT6N series have a continuous floor height of 350 mm, which is lowered to 300 mm in the door area. They started their service in the spring of 1990. The world's first series-produced tram vehicles that had a 100% low-floor section with no level differences within the vehicle were the R-cars of the Frankfurt am Main tram in 1993 . These railcars were originally developed by Düwag.

In a cost comparison of high-floor and low-floor trams, a survey among several tram operators showed that the maintenance of 100% low-floor trams incurred additional costs of 20% on average. The maintenance of the infrastructure is assumed to be 15% higher. The main reasons are the rapid introduction of design features that have not been tried and tested over a long period of time in series production (including running gears with idler gears , wheel hub motors ) and those that were actually considered out of date for reasons of comfort or wear, but promised advantages under the special requirements of low-floor technology (with the car body Torsionally rigidly connected bogies instead of bogies in multi-articulated vehicles, reduction in size or elimination of spring elements , idler gear sets that are not self-centering in the track ). On the other hand, carefully designed low-floor wagons can cause less wear and tear on the vehicle and track than high-floor wagons. For this reason, some manufacturers switched from fixed running gear to the use of bogies for vehicles with a 100% low-floor share, for example the Škoda 15T ForCity and Alstom Citadis X04 vehicles . Low-floor Jakobs bogies require a narrow passage in the lower area, but they do not require the platforms otherwise required in the drive modules.

  • Entry situation for the Geneva medium-floor wagons

  • A Bremen GT6N, here on a demonstration drive in Berlin, one of the first pure low-floor cars in Germany

  • Basel: Swiss standard car with a retrofitted low-floor center section

  • Prague: Detailed view of the bogie of the Škoda 15T low-floor technology

  • Interior view of a car with a low-floor center section in Graz

Omnibus and trolleybus

So-called "low-floor buses" were offered in isolated cases even before the Second World War ; but they did not correspond to the current definition of the term. These vehicles, which are at that time still on trucks - ladder frame - Chassis built, sometimes referred gradual poor rear entrances on behind the drive axle or platforms for standing passengers.

In the 1960s, there were low-floor solutions for special buses, especially in the area of ​​the central or rear door (after the drive axle), but these were not yet the focus of interest: Büssing Senator DD ( double-decker bus for Stockholm) and Trolleybus Solingen ( trolley bus with car bodies from Ludewig on three-axle chassis from Krupp for Solingen ). The one- and -a-half- deckers built by the Ludewig company also mostly had a low-floor entry in the basement in the rear, two-story half. Due to the mid-motors, which were widely used at the time and were mounted under the floor between the axles (only with the standardization of the public service buses, the current rear motors were used), it was possible to design the rear entry and standing room with little steps. Steps in the center aisle led to the rest of the passenger compartment.

Auwärter Neoplan presented the first “modern” low-floor bus in series in 1976 (N 814 with a wheel diameter of 832 mm, floor height 300 mm with stepless entry, but two steps in front of the rear axle, so actually a low-entry bus ); However, only a few copies could be sold, and the time was not yet ripe for significant demand. After Kässbohrer had presented another, moderately successful, low-floor bus in 1984 with the Setra S 300 NC, Neoplan tried a second attempt in 1987 in cooperation with the Stadtwerke München and set a stormy development in motion. Almost all city ​​buses manufactured between 1987 and 1997 were based on the standard bus II , which was originally developed as a standardized high-floor city bus by the Association of Public Transport Companies (VÖV). Auwärter Neoplan, Daimler-Benz and MAN developed the first low-floor city buses from this, initially with platforms under the seats in the front area. Since 1997, non-standardized solutions have emerged again.

Since the complicated drive construction for full low-floor buses is expensive and the number of seats is very small in comparison, there is a combination of low-floor bus and normal high-floor car: the low-entry bus , in which only the front car has a low floor, the rear end, however, has a normal rear axle with a simpler drive with a diesel engine and gearbox below the floor and can only be reached via steps or a ramp.

In 1992, Neoplan presented a different type of city bus concept with the N 4114 DE or DES: The passenger compartment is at ground level throughout and has no rear wheel arches (advantages in terms of maintenance and care). The engine is housed in a drive module "attached to the rear" above the steerable rear axle. The vehicles already had a diesel-electric drive. Depending on the local conditions, the vehicles could have been individually adapted (up to trolley drives and articulated trains with 18.4 m). Later used Neoplan this concept in hybrid - Midibus however N 6108. In both cases, it remained at a few copies. Only the Mercedes-Benz Cito , also a diesel-electric midibus designed according to the same principles, produced larger numbers, but was discontinued after a few years due to unsatisfactory market success.

To this day, intercity buses and light rail vehicles are not always low-floor, and coaches almost never, as these vehicles depend on large trunk spaces that can only be sensibly accommodated between the axles for reasons of space and driving dynamics (center of gravity). In addition, emphasis is placed on a high seating position and a good view in these vehicles. An accessibility can only ramps or in these vehicles therefore hoists are made possible as specially adapted wheelchair buses are used. In the long-distance bus service, the use of barrier-free vehicles has been mandatory for new registrations since 2016. Since double-decker and certain super high-decker coaches have stepless entrances, parking spaces for wheelchairs and prams can be created there without major structural effort.

Typical floor heights

For a better comparison, some typical floor heights follow:

Examples of low-floor vehicles

Entry into a low-floor tram in Darmstadt

Trolleybuses and omnibuses

Tram cars

Railway vehicles

Individual evidence

  1. ↑ Low-floor technology ( Memento of the original from January 16, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. on Mobi knowledge, buses and trains from A to Z @1@ 2Template: Webachiv / IABot / www.mobi-wissen.de
  2. ^ Ulrich Alois Benedikt Weidmann: The change of passengers in public transport. Dissertation ETH No. 10630. ETH Zurich, 1994, p. 125.
  3. ^ New York Railway Company is formed, Shonts Is Elected President, and Surface Lines Go Under New Control To-night. (PDF; 98.5 kB) In: The New York Times . December 31, 1911, accessed January 15, 2014 .
  4. ↑ Historic tram of the city of Frankfurt - from the "bathtub" to the S (super) class , accessed on January 15, 2014.
  5. ↑ orasulluibucur.blogspot.com, accessed October 16, 2019
  6. ↑ Prototipo 2800 on www.tramditorino.it
  7. ↑ Thomas Siefer: Final report - development of the Hanover city railway network - study on the use of low-floor vehicles. (PDF; 1.0 MB) Institute for Transport, Railway Construction and Operation (TU Braunschweig), March 2010, p. 111 , accessed on January 29, 2017 : “Another finding from companies that produce both high-floor and low-floor vehicles are in use is the direct cost comparison of both systems. For the maintenance and repair of the vehicles, additional costs of 20% are given on average. For the maintenance and repair of the infrastructure when using low-floor vehicles, costs are determined to be 15% higher. "
  8. ^ H. Hondius: Public transport low-floor rail vehicles on the rise. Episode 10, parts 1 and 2. In: City traffic . ISSN  0038-9013 , issue 1/1996, p. 21, and issue 2-3 / 1996, p. 22.
  9. ↑ The Avenio. PDF on ifs.rwth-aachen.de, p. 27 f.