When work on the Hudson River tunnels and New York's Penn Station was in progress, the type of electric locomotives to be used was an important consideration.
At that time only a few electric locomotives existed.
Several experimental locomotives were designed by railroad and Westinghouse engineers and tried on the West Jersey & Seashore Railroad track.
From these tests the DD1 class was developed.
The DD1s were used in pairs (back-to-back).
Thirty-three of these engines having Westinghouse equipment were built at Altoona.
They were capable of speeds up to 85 miles per hour (137 km/h).
Placed in service in 1910, they performed well, lasting in regular service through the 1940s.

Steel suburban passenger cars capable of being electrified for MU operation were designed due to the need for such cars in service to Penn Station through its associated tunnels and were designated MP54.
Designs for corresponding cars accommodating baggage and mail were produced also.
Eight of these cars were electrified with DC equipment to provide shuttle service from Penn Station to Manhattan Transfer between 1910 and 1922.
More extensive electrification plans required AC electrification, starting with 93 cars for the Paoli Line in 1915.
With the expansion of the AC electrification, additional MP54 cars were electrified or purchased new until a total of 481 cars was reached in 1951.
Replacement with newer types of cars began in 1958 and the last MP54 cars were retired in the early 1980s.

The single FF1 appeared in 1917 and ran experimentally for a number of years in preparation for electrification over the Allegheny Mountains that never came to fruition.
Its AC induction motors and side-rod drive powered six axles.
It developed a starting tractive force of 140,000 pounds, which was capable of ripping couplers out of the fragile wooden freight cars in use at the time.

In 1924 another side-rod locomotive was designed: (the L5 class).
Two DC locomotives were built for the New York electrified zone and a third, road number 3930, was AC-equipped and put in service at Philadelphia.
Later 21 more L-5 locomotives were built for the New York service.
A six-wheeled switching engine was the next electric motive power designed, being classified as B1.
Of the first 16 AC engines, two were used at Philadelphia and 14 on the Bay Ridge line, while 12 DC-equipped engines were assigned to Sunnyside Yard in Queens, New York.

The O1 class was a light passenger type.
Eight of these engines were built from June 1930 to December 1931.
The P5 class was also introduced, with two of this class being placed in service during July and August 1931.
Following these came the P5A, a slightly heavier design capable of traveling 80 miles per hour (130 km/h) and with a tractive force of 56,250 pounds.
In all, 89 of these locomotives were built.
The first had a box cab design and were placed in service in 1932.
The following year, the last 28 under construction were redesigned to have a streamlined type of cab.
Some engines underwent re-gearing for freight service.

In 1933 two entirely new locomotives were being planned: the R1 and the GG1 class.
The R-1 had a rigid frame for its four driving axles, while the GG-1 had two frames which were articulated.
Both of these prototypes, along with an O-1, a P5A and a K4s steam locomotive underwent exhaustive testing.
Testing was conducted over a special section of test track near Claymont, Delaware, and lasted for nearly two years.

As a result of these experiments, the GG1 type was chosen and the construction of 57 locomotives was authorized.
The first GG1 was finished in April and by August 1935 all 57 were completed.
These first GG1 engines were designated for passenger service, while most of the P5A type were made available for freight service.
Some of the later-built GG1s were assigned to freight service as well.
The total number of GG1s built was 139.
They are rated at 4,620 hp at speeds of 100 miles per hour (160 km/h).

On August 26, 1999, the U.S. Postal Service issued commemorative 33-cent All Aboard!
20th Century American Trains s
When work on the Hudson River tunnels and New York's Penn Station was in progress, the type of electric locomotives to be used was an important consideration. At that time only a few electric locomotives existed. Several experimental locomotives were designed by railroad and Westinghouse engineers and tried on the West Jersey & Seashore Railroad track. From these tests the DD1 class was developed. The DD1s were used in pairs (back-to-back). Thirty-three of these engines having Westinghouse equipment were built at Altoona. They were capable of speeds up to 85 miles per hour (137 km/h). Placed in service in 1910, they performed well, lasting in regular service through the 1940s.
Steel suburban passenger cars capable of being electrified for MU operation were designed due to the need for such cars in service to Penn Station through its associated tunnels and were designated MP54. Designs for corresponding cars accommodating baggage and mail were produced also. Eight of these cars were electrified with DC equipment to provide shuttle service from Penn Station to Manhattan Transfer between 1910 and 1922. More extensive electrification plans required AC electrification, starting with 93 cars for the Paoli Line in 1915. With the expansion of the AC electrification, additional MP54 cars were electrified or purchased new until a total of 481 cars was reached in 1951. Replacement with newer types of cars began in 1958 and the last MP54 cars were retired in the early 1980s.
The single FF1 appeared in 1917 and ran experimentally for a number of years in preparation for electrification over the Allegheny Mountains that never came to fruition. Its AC induction motors and side-rod drive powered six axles. It developed a starting tractive force of 140,000 pounds, which was capable of ripping couplers out of the fragile wooden freight cars in use at the time.
In 1924 another side-rod locomotive was designed: (the L5 class). Two DC locomotives were built for the New York electrified zone and a third, road number 3930, was AC-equipped and put in service at Philadelphia. Later 21 more L-5 locomotives were built for the New York service. A six-wheeled switching engine was the next electric motive power designed, being classified as B1. Of the first 16 AC engines, two were used at Philadelphia and 14 on the Bay Ridge line, while 12 DC-equipped engines were assigned to Sunnyside Yard in Queens, New York.
The O1 class was a light passenger type. Eight of these engines were built from June 1930 to December 1931. The P5 class was also introduced, with two of this class being placed in service during July and August 1931. Following these came the P5A, a slightly heavier design capable of traveling 80 miles per hour (130 km/h) and with a tractive force of 56,250 pounds. In all, 89 of these locomotives were built. The first had a box cab design and were placed in service in 1932. The following year, the last 28 under construction were redesigned to have a streamlined type of cab. Some engines underwent re-gearing for freight service.
In 1933 two entirely new locomotives were being planned: the R1 and the GG1 class. The R-1 had a rigid frame for its four driving axles, while the GG-1 had two frames which were articulated. Both of these prototypes, along with an O-1, a P5A and a K4s steam locomotive underwent exhaustive testing. Testing was conducted over a special section of test track near Claymont, Delaware, and lasted for nearly two years.
As a result of these experiments, the GG1 type was chosen and the construction of 57 locomotives was authorized. The first GG1 was finished in April and by August 1935 all 57 were completed. These first GG1 engines were designated for passenger service, while most of the P5A type were made available for freight service. Some of the later-built GG1s were assigned to freight service as well. The total number of GG1s built was 139. They are rated at 4,620 hp at speeds of 100 miles per hour (160 km/h).
On August 26, 1999, the U.S. Postal Service issued commemorative 33-cent All Aboard! 20th Century American Trains s
Pennsylvania Railroad