History
Charles P. Hatch of the Empire Transportation Company invented the rail tank car in 1865. It was a flat car with wooden banded tubes mounted on top, capable of carrying 3,500 gallons of crude oil on the Oil Creek and Warren and Franklin Railroads in Pennsylvania. Another inventor, Amos Densmore, built similar cars around the same time for the Atlantic & Great Western Railroad.

Shortly after that, railroads switched to larger wooden tanks mounted horizontally. Saddles bolted to flat cars gave the basic look of tanks cars used by the industry ever since. Empire Transportation Co. built the first metal tank cars in 1869. Mounted directly into wooden frames instead of flat cars, these heavy iron cars solved the problem of leaking wooden tanks and improved safety. As steel technology improved, steel replaced wrought iron making for lighter, but stronger tanks. These and later design improvements had a common goal - to increase transportation safety and efficiency.
 

Timeline

• 1865 - Wooden cars used for the first time to serve the oil fields of Pennsylvania.
• 1869 - Cast iron replaces wooden tanks. Capacity was about 3,500 gallons per car. The railroads have about 52,000 miles of track and it takes 8 days to go coast to coast on the new Transcontinental Railroad.
• 1888 - Tank car companies supply tank cars directly to the oil industry, instead of the railroads. Capacities range from 6,000 gallons to 10,000 gallons.
• 1901 - Gushers at Spindletop in East Texas bring the Lone Star State into the oil industry in a big way and help lead to development of rail lines to serve the wells and refineries of Texas and Oklahoma.
• 1903 - The tank car industry develops safety standards for construction. Now there are more than 10,000 tank cars in operation and over 260,000 miles of track.
• 1915 - A classification system is developed by the industry to ensure the right use of the tank cars for the right products. Now 50,000 tank cars serve the industry.
• 1920 - Welding technology replaces riveting in tank car construction, enhancing the safety of cars. There are now over 400,000 miles of track in the U.S.
• 1930 - Tank cars expand their use - 140,000 tank cars carry 103 commodities other than oil to market.
• 1940's - During World War II every tank car is used to transport oil for the war effort.
• 1950 - Pipelines and trucks lighten the load of tanks on railroads.

Overview
Commodities shipped in tank cars are quite diversified.

• Standard cars: These accomodate corn syrup, plastic pellets and resins, various kinds of oils, fertilizers, asphalt, petroleum, sulfur - even tomato paste and beer!  Options include steam coils, insulation (for temperature control), linings and valves.  Capacities range from 8,000 to 30,000 gallons.
• Pressure cars: Special values permit the transportion carbon dioxixe, chlorine, butane, liquefied petroleum gas (LPG) and anhydrous ammonia
• Acid cars: Special interior linings enable the transportation of sulfuric acid, oleum, phosphoric acid, ferric chloride and hydrochloric acid.
• Tank train: Interconnecting tank cars provides shippers with a quick and cost-effective method of moving large volumes of bulk liquids.

Tank cars range in length from 30 to 65 feet, but are limited by regulations to a capacity of 34,500 gallons. An interesting variant is the "Funnel Flow" tanker which is slightly sloped toward the middle from each end, giving it a bent appearance, but allowing it to be drained by gravity.

The large number of commodities classified as hazardous has resulted in regulations concerning tank car design and use. Included are structural requirements and temperature regualtion by insulation and heating coils. Little of this is evident from the outside however, and the tank car has, if anything, become even simplier and more elegant in appearance over time.

Tank cars can also be used for maintenace of way.  This is the case for numbers 97401-97403.

Tank cars can also be used for fire suppression. As it turns out, the railroad owns nine of these. They were old 9300-series revenue tanks that had expired on their hazmat certification and couldn't be used to haul fuel anymore. They were going to be scrapped, but instead a deal was made with the state DEC and the US Forest Service to rehab nine of them for water service. They were steam cleaned, restencilled and given those pretty new logos. They are filled with water here in Anchorage in the spring and distributed around the railroad to be available in an emergency should there be a wildfire. From south to north they are positioned as follows: Two at Moose Pass, Two at Talkeetna, One at Hurricane, Two at Healy, and Two at Clear Site. August 2008

Click on the pictures below for a larger view and additional information.