Amtrak Head End Power (HEP)

This page was last updated on November 16, 2011.

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Amtrak's Head End Power (HEP) Program

By Michael M. Palmieri

During the early part of the twentieth century, most railroad passenger cars in the U.S. were heated by steam provided by the locomotive’s boiler; and if the cars had electric lighting, the power came from an axle-driven generator and was stored in large, heavy batteries.

The early streamliners of the mid-1930’s, such as the UP M-10000 and the Burlington’s Zephyr, used electricity produced on the locomotive (head end power or HEP) for lighting and air conditioning; but almost all of the passenger cars built through the mid-1960’s continued to rely on steam for heat and axle-driven generators for power. One exception was commuter cars, for which HEP became more common following World War II.

Almost all of the cars acquired by Amtrak beginning in 1971 were steam-heated and had their own axle-driven generators. The arrival of 492 Amfleet cars between 1975 and 1977 began the wholesale change to HEP and allowed Amtrak to begin retiring older cars, especially coaches. While Amfleet cars came in several different interior configurations, most were 84-seat coaches intended for short- and medium-distance service, and none of them originally included sleeping accommodations. In 1976 Amtrak rebuilt 30 former U.S. Army kitchen cars into baggage cars 1350-1379, which could be used on either steam-heated or HEP trains.

Severe weather in January 1977 resulted in many steam-heated cars being bad-ordered with freeze damage. As a result of this equipment shortage, several medium- and long-distance trains such as the City of New Orleans were temporarily discontinued while the railroad rearranged its fleet. After a few weeks, these trains were reinstated with 1350-series baggage cars and Amfleet coaches and food-service cars; but no sleepers. This was certainly not a good situation for long-distance overnight trains!

With an immediate need for HEP sleepers, Amtrak began converting 25 cars in May 1977. The program initially involved some of the former Union Pacific Pacific-series 10-roomette/6-double-bedroom cars, as these were considered some of the railroad’s best sleepers. They had been well-maintained by the UP, and were stainless steel with good insulation, outside-swing-hanger trucks and disk brakes. They also had relatively reliable electro-mechanical air conditioning, which would be replaced during the conversion to HEP. These cars retained their former names, but were renumbered from the 2600-series into the 2900-series, keeping the same last two digits.

After 13 of the Pacific cars had been rebuilt, Amtrak decided to renumber the additional HEP sleepers into a contiguous block as they came out of the shop. It also decided to concentrate on the former Santa Fe Pine-series sleepers instead of the UP Pacific cars. The Pine cars had been built at the same time as the Pacific cars and they were very similar inside and out; but the Pine cars had relatively unreliable and difficult-to-maintain steam ejector air conditioning, so it made more sense to convert these cars ahead of the Pacific cars, with their better air conditioning.

In addition to the sleeper conversions, Amtrak began modifying additional baggage cars so they could run on both steam-heated and HEP trains. During 1977-78, seventy former Santa Fe cars were converted and renumbered: 1203-1249 had been built by Budd in 1953 and 1957 while the 1250-1272 had been constructed by ACF in 1950 and 1955.

The delivery of 284 Superliner cars between 1979 and 1981 allowed Amtrak to reequip all of its western long-distance trains and to continue retiring older cars. As the first Superliners were arriving, the railroad began a major, multi-year program to rebuild various types of cars for HEP operation on long-distance trains throughout the east, and this is when it adopted the Heritage Fleet name for all of the rebuilt cars. Amtrak’s preference for the HEP program was stainless steel cars, and about 70 per cent of the cars rebuilt for HEP operation had been constructed by Budd.

The arrival of 150 Amfleet II long-distance cars in 1981-1983 permitted the retirement of even more of the old equipment, and the conversion of the Silver Star to HEP in March 1982 made Amtrak an all-HEP railroad.

Additional Information

Because of the lengths of trains and the high power requirements, HEP is supplied, in North America, as three-phase AC at 480 V (standard in the US and for Canada's VIA). Power is provided for all heating, cooling, and lighting electrical loads.

July 1973
Amtrak took delivery of the first of 40 new SDP40F locomotives from Electro-Motive, meant to replace 74 ex AT&SF F-units. The new locomotives were equipped with two steam generators, with the capability for later installation of two 375-kilowatt auxiliary diesel generators to furnish the planned 480-volt three-phase A.C. electrical system.

In 1977, following the delivery of their new Amfleet cars in 1975 and 1976, and new F40PH locomotives also in 1976, Amtrak began a program to rebuild its fleet of previously railroad-owned passenger cars from being steam-heated cars, to electric-power, known as head end power, or HEP. The work was done at Amtrak's Beech Grove shops, near Indianapolis, Indiana, and the program lasted through the mid 1980s, with only about one-third of the fleet being completed. Cars were selected for HEP conversion as other repair work was needed, with an emphasis placed on Budd-built cars in a few standard configurations, although many of the newest ex-UP non-Budd cars were included. After completion, most of the HEP cars were renumbered into a new number series. At about the same time, Amtrak designated its previously railroad-owned passenger cars, rebuilt or not, as its Heritage fleet. The previously railroad-owned cars were commonly known as "conventional" cars. The dome cars were added to the HEP program later on, and about 20 sleepers that were assigned HEP numbers were never rebuilt with electric power. (part from Mike Palmieri, emails dated November 9 and 10, 2011)

In 1975, Amtrak started to take delivery of the all-electric Amfleet car, hauled by General Electric (GE) P30CH and, later, EMD F40PH locomotives, both unit types being equipped to furnish HEP. Following the introduction of the Amfleet fleet, the (also all-electric) Superliner railcar was placed into operation for servicing long-distance western routes. Amtrak subsequently converted a portion of the steam heated fleet to all-electric operation using HEP, and retired the remaining unconverted cars. (Wikipedia; http://en.wikipedia.org/wiki/Head_end_power)

To obtain Amtrak HEP certification, each car must be designed to carry the full electrical load of the train since, theoretically, any car could be the car immediately following the locomotive or generator car that is supplying the electrical power. Each car must have compatible electrical plugs and sockets at each end and these plugs and sockets scheme is designed to both transmit power while protecting passengers. To accomplish this, each car has a plug and receptacle on each side of each end (i.e., each corner) for a total of four plugs and four receptacles. When connected together, the plug and receptacle on each corner is connected to the plug and receptacle of the adjacent car. In this manner, the load is actually split among the four sets of cables and the car is part of the electrical circuit for the entire train. The last car in the at each end of the train has its plug on one side connected to the receptacle on the other side. Amtrak's Heritage Fleet program was started in 1977 to equip older cars from Amtrak's predecessor railroads to Head End Power. These conversions were performed at Amtrak's heavy repair center in Beech Grove, Indiana, outside of Indianapolis. The program was completed by the mid 1980's. (Source; http://www.pullman-car.com/Restoration/HEP/hep%20description.html)

Amtrak's HEP-Equipped Cars (delivered new)

(click here for more information about Amtrak's cars equipped with HEP, including Amfleet I and Amfleet II, Superliner I and Superliner II, Horizon fleet, and Viewliners)

Amtrak's HEP-Equipped Locomotives (delivered new)

(click here for more information about Amtrak's first locomotives, including the SDP40Fs and the later locomotives equipped with HEP)

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