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Locomotive Class Lights and Their Function

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WWI station

Green class lights on the sides of the smokebox indicate that a second section will be following this train. From the soldier on the platform, it is likely one of the many multi-section troop trains run during the first World War.

©2010 Ryan C Kunkle, licensed to About.com, Inc.
Definition:

Class lights once played an impotant role in running a railroad. These lights, often supplemented by flags during the day, told other trains, work crews and operators in stations and towers whether this was a regularly scheduled train, or something not in the timetable.

In the earliest days of railroading, the trains were the fastest means of communication to be had. To make sure the railroad ran safely and efficently, trains had to adhere strictly to a timetable and operate by rigid rules. But what if the schedule needed to change?

A common problem occured when the railroad needed to run an extra train. This train might be a passenger or freight special, or there might be so much traffic moving that a second section of a scheduled train was needed.

Before the telegraph and radio, the first sign of any change in the schedule was often the train itself. That could cause a serious problem!

A simple set of flags and lights solved this problem. And the practice continued for a long time as a safeguard even long after the communications problems improved.

The primary colors used in these lights were white and green. White meant the train was an extra section, not shown in the timetable. These could be passenger, freight or work trains, or even just a light engine move.

Green flags indicated that an extra train was following this one on the same schedule. These extras operated as an extra section. It was not uncommon for extra sections of passenger trains to run during the peak holiday travel seasons.

Freight extra sections could run anytime there were more cars than could be pulled efficiently by a single set of power. It was often easier to run two shorter trains than one extra-long one due to the length of sidings and the top speed the train could attain.

If more than two sections were needed, the last one would carry white lights and flags and all others in front would display green.

Different railroads ended this practice at different times. Improved communications and signalling systems like Centralized Traffic Control (CTC) greatly reduced the need for the flags. Some railroads curtailed them as early as the 1930s. Others retained the practice well into the 1980s. Canadian railroads were among the last of the large roads to abandon the practice.

Railroaders do like tradition however, so you'll still find the practice listed in many rule books even if it is no longer readily used. And special passenger excursions will often fly white flags today - even though the railroad operating crew has known about them for months in advance.

Class lights should not be confused with marker lights which display a red light to the front or rear of a train. On most steam locomotives these were separate light castings. Many diesels used a single light with multiple colored lenses.

The railroads also used blue flags to indicate locomotives or tracks out of service. Lights would be used at night, but these were not permanently attached to the locomotives.

On your model railroad, these lights would normally be off, unless the train really was an extra or had a section following. Working lights are quite common in O Gauge trains, although they aren't always wired to operate appropriately.

Small jewels are avalable as separate detail parts that can be added to models in many scales to give a nice effect. Lights could also be added using some of the new micro-LEDs and extra functions on a DCC decoder.

You can also the lights and flags as more than just props at your next operating session. Whether you operate with a complete timetable, or just want to throw out the occasional extra section, now your operators will know what to expect.

Small flags can also be fasioned from a small piece of wire and colored paper or styrene plastic. In later years, many railroads used metal "flags."

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