Tank wagons

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Scheme drawing
Tank car for transporting alcohol

A tank car ( KWG for short ) is a rail freight car with one or more closed containers (e.g. under pressure ) that is used to transport liquids and gases . A special form of this freight car was the pot car , which has not been found for a long time. Container wagons for the transport of powdery goods are not classed as tank wagons, but are class U special wagons .

Road vehicles for the transport of liquids and gases are called tank trucks or "Tkw".

Structure and designs

Narrow-gauge tank car 750 mm
Old tank car as an exhibit in the Mid Continent Railroad Museum in the USA

In general, tank wagons are divided into two different types:

on the one hand in tank wagons for compressed gases, with the three sub-classes
  • Pressurized gas tank wagons with bottom discharge,
  • Pressurized gas tank wagons with top discharge,
  • Tank wagons for cryogenic liquefied gases;
on the other hand in tank wagons for liquids, again with three sub-classes
  • Tank wagons with bottom emptying, also called ( pars pro toto ) "mineral oil tank wagons ",
  • Tank wagons with top discharge ("chemical tank wagons"),
  • Tank cars with top and bottom emptying.
Pressurized gas tank car (rear) and insulated tank car in the Bitterfeld-Wolfen Chemical Park

Tank wagons are equipped with a specific tank or pressure vessel , depending on their use , and (depending on the load weight) are built as freight wagons with two bogies or with two axles. The loading volume is 20 m³ to 120 m³ depending on the version. Tank wagons for transporting gases are usually protected from direct sunlight by a sun protection plate. Newer pressurized gas tank wagons do not have a sun protection roof. The thermal insulation is achieved here by a greater wall thickness of the boiler.

Depending on the design, tank wagons can be filled or emptied from above, below or from above and below.

“Pressurized gas tank wagons” are marked in Europe with a 30 cm high, orange stripe that surrounds the tank halfway up. They are mostly loaded and unloaded using devices that can be operated from the ground (bottom emptying).

" Mineral oil tank wagons " are usually filled from above and emptied from below. Many trolleys of this type have a forced ventilation system to prevent the trolley from implosion during emptying. This ensures that a valve for ventilation opens and closes at the same time as the nozzle for discharge. The trolleys with a forced ventilation system are marked with a vertical, white band in the middle of the trolley. The dome lid does not have to be opened here for emptying. Chemical tank wagons are usually filled and emptied from above , except for less hazardous chemicals . Air or nitrogen is pumped into the interior of the vehicle via a pressure port, the cargo is then pressed out of the tank via a riser pipe and filled into another container via a connected line. It is also possible to suck off the material, although here, too, attention must be paid to the ventilation to prevent implosion.


  • Food transport (milk, beer, cooking oil, etc.)
  • Petroleum or petroleum product transportation
  • Chemical transport
  • Liquefied gas transport
  • Compressed gas transport

economic aspects

In contrast to most other types of wagons, tank wagons (KWG) are mostly owned by the shipper or a special wagon rental company such as VTG AG or GATX , not the railway company. The German railway , for example does not own tankers. This fact is justified on the one hand by individual product requirements (e.g. pressure, temperature) and on the other hand by the increased safety requirements in the dangerous goods area (RID). Therefore, dedicated providers and investors are in demand who take on the complex management of KWG parks. This includes maintenance and the timely completion of technical tests. A tank wagon is made available to a tenant with the desired degree of purity and returned by him at the end of the tenancy, either cleaned or uncleaned by arrangement. The cleaning is mostly carried out by specialized companies (i.e. neither the tenant nor the landlord). Here are environmental regulations complied with.

Above all, the liberalization of rail freight transport resulted in a need for action in the wagon environment, which has led to the development of service providers for everything to do with tank wagons. KWG landlords also take on overall services, including carrier management. COTIF 1999, which came into force in 2006, redefined the market environment . It allows wagon rental companies to put wagons into the rail network independently without having to use a third party (mostly former state-owned RUs ).


Many tank wagons are so stable that they remain tight even if they derail and tip over. In the course of more than 100 years of use of tank wagons, however, there were some serious accidents. The following is an excerpt from the list of serious accidents in rail traffic :

  • Erzsébetváros ( Hungary ) - rear-end collision due to neglected safety measures: February 5, 1913 - At Erzsébetváros (today Dumbrăveni ) the express train 601 of the Hungarian State Railways coming from Bucharest collided with an unscheduled stopping freight train and destroyed tank wagons that were fueled with petroleum immediately caught fire. The result was three deaths. Prince Eitel Friedrich von Prussia , second son of Kaiser Wilhelm II , traveling back to Berlin in the last carriage of the express train , was unharmed.Hungary 1867Hungary 
  • Ingolstadt ( Federal Republic of Germany ) - rear-end collision and subsequent major fire: March 2, 1972 - Due to a dispatcher error, a freight train from Ingolstadt Nord station inadvertently exited in the direction of Ingolstadt Hbf and ran into a second freight train waiting in front of the entrance signal. This consisted of tank wagons loaded with petroleum products, some of which caught fire. Four people died in the accident and the dispatcher took his own life.Germany Federal RepublicFederal Republic of Germany 
  • Zurich-Affoltern ( Switzerland ) - major fire after derailment of a tank car train. March 8, 1994 . 3 houses burned down completely, a fourth partially. Main article: Zurich-Affoltern railway accident
  • Elsterwerda ( Germany ) - Major fire after derailment of a tank car train. November 20, 1997 .GermanyGermany 
  • Minot, United States - Derailment after broken rail: January 18, 2002 - West of Minot , North Dakota , a freight train derailed, with five pressurized tank wagons carrying toxic , corrosive ammonia gas exploded. Also due to the failure of the local disaster control , one resident died, 11 people were seriously injured, 322 were slightly injured, around 11,600 residents had to be evacuated, the property damage amounted to more than $ 10 millionUnited StatesUnited States 
  • Neyschabur ( Iran ) - A train laden with chemicals explodes: February 18, 2004 - A ghost train near the Iranian city ​​of Neyschabur (Nishapur) started moving. After a few kilometers, some of the cars derailed and caught fire. Several tank wagons exploded during the extinguishing work. 320 people died, mostly firefighters, 460 were injured.IranIran 
  • Wetteren (east of Ghent , East Flanders Province ( Belgium )) - May 4, 2013 - Six tank wagons of a freight train consisting of 13 wagons derailed at night; several of them fell over and slid down an embankment; three of them exploded. The accident happened after a construction site, when the train changed the track at a switch. The material in at least one of the kettles was acrylonitrile . They burned for 16 hours with a lot of smoke. The fire brigade had the tank wagons burned out in order not to let any more toxic gases "develop". A local resident died of toxic chemicals in the air in his home.BelgiumBelgium 

North America

Derailed, ripped open tankers
Two different tank
trucks according to specification 111A100W1

In America there was an oil boom in the Bakken Formation in North Dakota for which no pipeline capacity was available. Therefore, tank transports by rail were used, which have been increasing rapidly since 2011.

As a result, there was also an increase in oil accidents, as the tank wagons built according to the American DOT-111 standard can easily tear open if derailed.

Accidents (selection):

  • Lac-Mégantic ( Canada ) - Several tank cars loaded with crude oil derailed and exploded: July 6, 2013 - A driverless freight train with 72 tank cars started moving. After a few kilometers, some of the cars derailed in the middle of the Canadian town of Lac-Mégantic and caught fire. At least 20 people died in the following explosion.CanadaCanada 

As a consequence, the DOT-111 tank wagons, which still make up two thirds of the entire North American fleet, are to be overhauled or replaced by new TC-117 wagons.

Images of various tank cars

See also

Web links

Commons : Tank Car  - Collection of pictures, videos and audio files

Individual evidence

  1. tagesspiegel.de , spiegel.de
  2. ^ Daniel Gross: The Dakota Access Pipeline Should've Happened 10 Years Ago . In: Slate . October 21, 2016 ( slate.com ).
  3. a b Michael W. Robbins: Why do trains carrying oil keep blowing up? In: Mother Jones . May 27, 2014 ( motherjones.com ).
  4. Oregon derailment is latest in string of US oil train crashes . In: The Oregonian . ( oregonlive.com ).
  5. Train accident in Canada: tank car explosion devastates small town. In: Spiegel Online . July 6, 2013, accessed October 24, 2016 .
  6. ^ Collision in North Dakota: Tanker truck explodes . In: Neue Zürcher Zeitung . December 31, 2013 ( nzz.ch ).
  7. AAR: Railroad Tank Cars ( Memento from July 1, 2014 in the Internet Archive )