Railroad Technology

As the basis for a Skype virtual SIG

PresentationKen 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• 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 CONTROLMainline

single, double, multitracksidings, crossovers along lines, business side tracks

Crossing of different lines at grade levelLift and swing bridgesRoad crossingsStation 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

• 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 leversnon-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

• 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 – PacificSunset Limited Luxury Route

Now Amtrak

CAB SIGNALSsteam 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 StationNorth 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

• 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 TransportationSimulator Display

Diesel standard cab with radio

St. Paul Roundhouse Display

Simulator Screen

CONCLUSION• 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.