Railroad Technology
As the basis for a
Skype virtual SIG
Presentation
Ken Sandock
10-1-14
• Railroad technology has always been at the
forefront of engineering:
– Steam
– Hydraulic
– Pneumatic
– Electrical
– Electronic
– Combustion - pollution
HISTORY
• Cars had mechanical brakes operated by
brakemen on top of cars turning wheels
• George Westinghouse invented the Safety Air
Brake in 1868, allowed faster running
• Manual mechanical and other systems soon
became inadequate to safely control traffic
• Electric signals and turnout “switch” control
enabled safer more efficient operation – also
invented and developed by Westinghouse
Track Circuit
• Line is divided into insulated blocks ~ 1 mile
• Battery across rails keeps relay closed
– Train wheels short track and opens relay indicating train location and
setting stop signal, adjacent signals, crossing guards, etc
• Fail-safe – break or power loss opens relay, still in use + newer methods
Control devices - semaphore
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Hand-operated from 1841
Electro-pneumatic from 1881
Motorized from 1890s
Lights (flame and bulb) and lenses soon added
– These were 3-12 volts from large glass batteries
• Could be controlled locally or remotely,
– Dispatcher or automatic track relay
• Power loss goes to stop indication – fail safe
Light signals
• PRR positional signal 1915 – multi bulbs
– simulate semaphore, no moving parts, redundant
• Searchlight 1932 – better optics, see farther
– Moving filter, removed along I-10 this year
– Replaced by hood multibulb-filter lens units
• Colors set by national code in 1905
• Traffic signals came in 1912-14, 2 color
• Many now use LEDs
• Train must stop at unlit signal – fail safe
IRM light display
WHAT TO CONTROL
Mainline
single, double, multitrack
sidings, crossovers along lines, business side tracks
Crossing of different lines at grade level
Lift and swing bridges
Road crossings
Station tracks – control dozens to hundreds of trains
at large and small stations every day manually
from the 30s and 40s and today with computers
How to control
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Local at trackside
Armstrong lever – rod from tower
Electric (pneumatic) from tower
Mechanical interlocking machine
CTC Relay logic interlocking *
Computer logic interlocking *
– * long distance operation hundreds of miles.
– * big RRs have one central dispatch location
Armstrong tower levers
non-interlocking, no indicator
HOW TO COMUNICATE
• Track warrants, timetables, train orders
– Still used, led to time zones in US
• Bells, whistles, hand signs, lanterns
• Telegraph orders and news 1850-70s
– How Harvey Houses filled orders quickly
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Telephone to control points and wayside
Multiple wires on poles for signals, control
Radio in engines 1950s, microwave wayside
Fiber optic: So Pac Rr Info Net Technology
– Sold excess capacity commercially
• Coded signals through rails, now can control engine
functions, monitor conditions
Southern – Pacific
Sunset Limited Luxury Route
Now Amtrak
CAB SIGNALS
steam engines electric
MECHANICAL INTERLOCK
• Levers control turnouts and signals
• In large cabinets with cams preventing unsafe
conflicting operation
• Indicator board above shows occupied block
and turnout, signal status
• Used for stations and line crossings
Chicago Union Station
North Tower 2013 - inactive
Interlocking Machine
Centralized Traffic Control
• Dispatcher panel controlled many miles
• 2 panels: Yuma-Tucson, Tucson-El Paso
– Tucson >computer> California (SP) > Omaha (UP)
• Switches operated relays with closed loop to
track sensors, turnout and signal conditions.
• Relays wired to automatically give preferences
of routing under routine conditions, fail safe
• Automatic Train Control with manual override
CTC for Yuma-Tucson in Tucson Depot
UP “mission control”
MSP Twin Cities BNSF monitor
IRM CTC and relays
POSITIVE TRAIN CONTROL
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Now being implemented by law
Must be compatible all railroads and Amtrak
Involves track and engine sensors, GPS
Can control engine functions and stop train
Uses radio data communication each block
Works over standard dispatcher system
Engine Control
• Electric and diesel engines have electric
control, including rapid transit and light rail
– Analog or digital control, with AC or DC motors
– All have standard interface for ~50 years
• MU - Multiple Unit operation
– Standard plugs, signal lines, protocols
– Allow multiple engines’ control from lead cab
– Allow push-pull transit with engineer in end coach
– Allow radio remote control and helper engines in
middle and at end of train
SIMULATORS
• Home computer programs allow operation
– Keyboard, joystick, and custom consol
– Museums can use diesel control stands.
– All these functions can be applied to model RR
layouts – CTC, ATC, computer control
• Automatic or multiple operator control
• Railroad companies use full sized units to train
and test engineers with different situations
– Similar to pilots
Diesel cab with desk controls
Southern Arizona Transportation
Simulator Display
Diesel standard cab with radio
St. Paul Roundhouse Display
Simulator Screen
CONCLUSION
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TECHNOLOGY DEMONSTRATING TECHNOLOGY
• The caboose left at the end of the 20th century. It’s job was
train observation for defects and monitor brake air pressure.
The conductor could stop the train with a brake valve. The
lights marked the end of the train. You can see this at the
Gadsden-Pacific model train museum here in Tucson with a
full size equiped caboose open for visiting.
• Wayside detectors inspect the trains now
• Brake pressure is monitored by FRED, flashing rear end device
with radio signals to the engineer. We have displays of all in
this talk at the Southern Arizona Transportation Museum, at
the Amtrak Depot by Maynard’s and Hotel Congress.