Harris Switch Tower
Encyclopedia
Harris Switch Tower, also known as HG Tower or Harris Tower, is an interlocking tower
in Harrisburg
, Pennsylvania
in the United States
. The tower was built in 1929 by the Pennsylvania Railroad
and remained in operation until it was closed in 1991 by Amtrak
. Harris was purchased by the local chapter of the National Railway Historical Society
in 1992 and listed on the National Register of Historic Places
in 1994.
-structure located on Walnut Street in Harrisburg
, Pennsylvania
. It is situated southeast of the Pennsylvania State Capitol Complex
and between the State Street Bridge
and the Harrisburg Transportation Center
. Its Flemish bond brickwork sits atop a partially exposed, concrete foundation; the stories are visually separated by a soldier course.
The second floor contains the tower's interlocking
machine, used to control signals and switches
. It contains many steel bars that interlock with one another to prevent conflicts and sudden changes that could cause a derailment. The machine is 24 inch long, 6 inch wide and 4 inch tall. The front has 115 levers which were used to control all of the switches and signals in Harris Tower's territory. A 4 inch tall model board is mounted above the machine. The 450 indicator lamps of the model board show the position of switches and current locations of trains within the interlocking limits. The interlocking machine is still operable, but is connected to a computer, rather than the signals and switches it once controlled. The computer is programmed to simulate train movements through the interlocking using Pennsylvania Railroad timetables from the early 1940s.
completed its main line
across the Allegheny Mountains
, connecting Philadelphia to Pittsburgh, in 1854. By the 1870s, the Pennsylvania had connected New York City
to Chicago
and St. Louis
; consequently, all freight and passenger traffic from New York, Philadelphia, Baltimore
and Washington, D.C.
, had to pass through Harrisburg before heading west. Harris Tower, then called HG Tower in a holdover from the simplification needed when railroad communications were sent via telegraph
, was built in 1929. It replaced two nearby towers that had been constructed in 1889. The consolidation reduced the manpower needed to control the 3300 feet (1,005.8 m) and 15 sets of tracks north of Pennsylvania Station
from 21 to 12. Harris Tower was put into service on April 26, 1930.
Some of the tracks controlled by Harris were removed, and the model board revised, when a new engine terminal was built in conjunction with the electrification of the line between Harrisburg and Philadelphia in 1938. The engine terminal assisted in the switching of electric locomotives to steam or diesel locomotives for the trip west of Harrisburg. The Pennsylvania merged with the New York Central Railroad
in 1968 to form Penn Central. In 1971, Amtrak
took over intercity passenger service from Penn Central and also took possession of many ex-Pennsylvania Railroad tracks and facilities, including Harris Tower. Penn Central was taken over by Conrail in 1976. Conrail modernized its signalling control
system in 1989 and consolidated it into a centralized traffic control
system in the Harrisburg Transportation Center
. Consequently, Harris Tower was reduced to controlling only four Amtrak trains a day. The tower was closed on November 15, 1991. The Harrisburg-based chapter of the National Railway Historical Society
purchased Harris Tower from Amtrak on July 24, 1992. The tower was listed on the National Register of Historic Places
on August 30, 1994.
Signalling control
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable...
in Harrisburg
Harrisburg, Pennsylvania
Harrisburg is the capital of Pennsylvania. As of the 2010 census, the city had a population of 49,528, making it the ninth largest city in Pennsylvania...
, Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. The tower was built in 1929 by the Pennsylvania Railroad
Pennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
and remained in operation until it was closed in 1991 by Amtrak
Amtrak
The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...
. Harris was purchased by the local chapter of the National Railway Historical Society
National Railway Historical Society
The National Railway Historical Society is a non-profit organization established in 1935 in the United States to promote interest in, and appreciation for, the historical development of railroads. It is headquartered in Philadelphia, Pennsylvania and organized into 16 regions and...
in 1992 and listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
in 1994.
Design
Harris Tower is a two-story, Colonial RevivalColonial Revival architecture
The Colonial Revival was a nationalistic architectural style, garden design, and interior design movement in the United States which sought to revive elements of Georgian architecture, part of a broader Colonial Revival Movement in the arts. In the early 1890s Americans began to value their own...
-structure located on Walnut Street in Harrisburg
Harrisburg, Pennsylvania
Harrisburg is the capital of Pennsylvania. As of the 2010 census, the city had a population of 49,528, making it the ninth largest city in Pennsylvania...
, Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
. It is situated southeast of the Pennsylvania State Capitol Complex
Pennsylvania State Capitol Complex
The Pennsylvania State Capitol Complex, located in downtown Harrisburg, Pennsylvania, is the administrative hub of the government of the Commonwealth of Pennsylvania. At the center of the complex is the State Capitol with its gilt and marble halls, vast rotunda, murals and sculpture, sparkling...
and between the State Street Bridge
State Street Bridge (Harrisburg, Pennsylvania)
The State Street Bridge, also known as the Soldiers and Sailors Memorial Bridge, is a concrete, deck arch bridge that spans Pennsylvania Route 230 and Paxton Creek in Harrisburg, Pennsylvania...
and the Harrisburg Transportation Center
Harrisburg Transportation Center
The Harrisburg Transportation Center is a large railway station and transportation hub in Harrisburg, Pennsylvania. It is located on the eastern edge of Downtown Harrisburg between the intersections of Aberdeen and Market Streets and 4th and Chestnut Streets...
. Its Flemish bond brickwork sits atop a partially exposed, concrete foundation; the stories are visually separated by a soldier course.
The second floor contains the tower's interlocking
Interlocking
In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant...
machine, used to control signals and switches
Railroad switch
A railroad switch, turnout or [set of] points is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction....
. It contains many steel bars that interlock with one another to prevent conflicts and sudden changes that could cause a derailment. The machine is 24 inch long, 6 inch wide and 4 inch tall. The front has 115 levers which were used to control all of the switches and signals in Harris Tower's territory. A 4 inch tall model board is mounted above the machine. The 450 indicator lamps of the model board show the position of switches and current locations of trains within the interlocking limits. The interlocking machine is still operable, but is connected to a computer, rather than the signals and switches it once controlled. The computer is programmed to simulate train movements through the interlocking using Pennsylvania Railroad timetables from the early 1940s.
History
The Pennsylvania RailroadPennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
completed its main line
Main Line (Pennsylvania Railroad)
The Main Line of the Pennsylvania Railroad was a rail line in the U.S. state of Pennsylvania, connecting Philadelphia with Pittsburgh via Harrisburg...
across the Allegheny Mountains
Allegheny Mountains
The Allegheny Mountain Range , also spelled Alleghany, Allegany and, informally, the Alleghenies, is part of the vast Appalachian Mountain Range of the eastern United States and Canada...
, connecting Philadelphia to Pittsburgh, in 1854. By the 1870s, the Pennsylvania had connected New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
to Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
and St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
; consequently, all freight and passenger traffic from New York, Philadelphia, Baltimore
Baltimore
Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...
and Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
, had to pass through Harrisburg before heading west. Harris Tower, then called HG Tower in a holdover from the simplification needed when railroad communications were sent via telegraph
Electrical telegraph
An electrical telegraph is a telegraph that uses electrical signals, usually conveyed via telecommunication lines or radio. The electromagnetic telegraph is a device for human-to-human transmission of coded text messages....
, was built in 1929. It replaced two nearby towers that had been constructed in 1889. The consolidation reduced the manpower needed to control the 3300 feet (1,005.8 m) and 15 sets of tracks north of Pennsylvania Station
Harrisburg Transportation Center
The Harrisburg Transportation Center is a large railway station and transportation hub in Harrisburg, Pennsylvania. It is located on the eastern edge of Downtown Harrisburg between the intersections of Aberdeen and Market Streets and 4th and Chestnut Streets...
from 21 to 12. Harris Tower was put into service on April 26, 1930.
Some of the tracks controlled by Harris were removed, and the model board revised, when a new engine terminal was built in conjunction with the electrification of the line between Harrisburg and Philadelphia in 1938. The engine terminal assisted in the switching of electric locomotives to steam or diesel locomotives for the trip west of Harrisburg. The Pennsylvania merged with the New York Central Railroad
New York Central Railroad
The New York Central Railroad , known simply as the New York Central in its publicity, was a railroad operating in the Northeastern United States...
in 1968 to form Penn Central. In 1971, Amtrak
Amtrak
The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...
took over intercity passenger service from Penn Central and also took possession of many ex-Pennsylvania Railroad tracks and facilities, including Harris Tower. Penn Central was taken over by Conrail in 1976. Conrail modernized its signalling control
Signalling control
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable...
system in 1989 and consolidated it into a centralized traffic control
Centralized traffic control
Centralized traffic control is a form of railway signalling that originated in North America and centralizes train routing decisions that were previously carried out by local signal operators or the train crews themselves. The system consists of a centralized train dispatcher's office that...
system in the Harrisburg Transportation Center
Harrisburg Transportation Center
The Harrisburg Transportation Center is a large railway station and transportation hub in Harrisburg, Pennsylvania. It is located on the eastern edge of Downtown Harrisburg between the intersections of Aberdeen and Market Streets and 4th and Chestnut Streets...
. Consequently, Harris Tower was reduced to controlling only four Amtrak trains a day. The tower was closed on November 15, 1991. The Harrisburg-based chapter of the National Railway Historical Society
National Railway Historical Society
The National Railway Historical Society is a non-profit organization established in 1935 in the United States to promote interest in, and appreciation for, the historical development of railroads. It is headquartered in Philadelphia, Pennsylvania and organized into 16 regions and...
purchased Harris Tower from Amtrak on July 24, 1992. The tower was listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on August 30, 1994.
See also
- National Register of Historic Places listings in Dauphin County, Pennsylvania
External links
- Harris Tower and National Railway Historical Society (NRHS) - Harrisburg Chapter
- [PRR interlocking diagrams, Harrisburg to Philadelphia] Shows a diagram of the switches and signals controlled by Harris in 1962.