railroad signals

RAILROAD SIGNALS

Railroad Signals

Used to prevent train collisions Collisions are a major concern as trains

travel on fixed paths A freight train travelling at 55 mph takes

over a mile to stop A train will not be able to stop before

hitting an object after the engineer sees it

Original Fixed Signals

Early signals were flags or lamps placed at a predetermined stopping distance from an obstacle

Used before stations and draw bridges

Only other control system was by timetables

Ball Signals

Began in the 1830s

Balls of different colors and shapes were raised and lowered to show “Safety” or “Danger”

Vane Signals

Began in the 1840s

Several designs

Different shapes or colors described specific situations

Block Signaling

Tracks divided into sections known as “blocks”

Used to space trains far enough apart so they could not collide

Signalmen were stationed at the beginning of each block and changed the signal

Signalmen sent telegraphs to confirm when trains passed

Widely used after 1850

Semaphores

Often used to tell an engineer they need to stop and receive a telegraph

Common in 1870s Downside was colors

were not standardized Originally white used

instead of green as green was difficult to produce

Electrical Signals

Allowed automatic signal operation from long distances

Created closed-circuit tracks by using the rails as conductors

Original idea in 1872, but at the time was not able to power a signal

Light signals Previous signals hard to distinguish from long

distances and only able to be seen during day

Position signals introduced in 1920s

Red, yellow and green lights added in 1950s

Modern Signals

Electrical currents in tracks determines if block is occupied

Block lengths may be variable and computer-generated

Signal is green if next two blocks are unoccupied

Yellow if second is occupied

Red if next is occupied

Careers in the Rail Industry• Salary: $51,000 - $61,000• Education: Bachelor’s• Experience: 0-2 years

Civil Engineer

• Salary: $56,000 - $65,000• Education: Bachelor’s • Experience: 0-2 years

Electrical Engineer

• Salary: $50,000 - $57,000• Education: Bachelor’s• Experience: 4 years

Geotechnical Engineer

• Salary: $30,000 - $39,000• Education: High School Diploma/G.E.D.• Experience: 0-2 years

Welder


Heavy Assembler

Civil Engineer

Designs and supervises construction projects such as airports, bridges, channels, dams, railroads and roads

Responsibilities also include estimating costs and personnel and material needs, preparing proposals and establishing completion dates


Civil Engineer


Electrical Engineer




Welder


Heavy Assembler

Electrical Engineer

Designs, tests, installs and maintains large-scale electronic equipment or machinery for use in manufacturing or power generation or transmission

May use computer-assisted engineering and design software and equipment to perform assignments


Civil Engineer


Electrical Engineer




Welder


Heavy Assembler


Prepares and inspects projects involving drilling and exploration

Responsible for geological mapping, report writing, site characterization, numerical modeling and analysis of excavations/supports


Civil Engineer


Electrical Engineer




Welder


Heavy Assembler

Welder

Joins, fabricates and repairs metal and other weldable material by applying appropriate welding techniques

Interprets blueprints, specifications, diagrams or schematics to determine appropriate welding process

Inspects completed welds to determine structural soundness


Civil Engineer


Electrical Engineer




Welder


Heavy Assembler

Heavy Assembler

Assembles fabricated parts to relatively large or heavy subassemblies and complete units

Tests and calibrates parts and mechanisms to meet tolerances and product specifications

Electrical Circuits Activity

Characteristics of electrical circuits have a closed loop have a full, circular path

Today’s activity is to build basic circuits with batteries, switches and lights

There are two ways to wire lights: Series – if one lights go out, both go out Parallel – possible for one light to work while

other does not One will give you brighter lights than the other

Helpful Hints

The green screw on the light switch is a ground, do not use this screw

Don’t attach both wires to the same end of the battery

Turn the switch to off until you are done wiring, it makes it easier to see how bright the lights are

railroad signals

Education

bachelors experience

years welder salary

years civil engineer

years heavy assembler

high school diplomag

heavy subassemblies

electrical currents

s downside