Signals on the railroad are found in many forms. White flags, class lights, or markers on a locomotive indicate that this train is an "extra" or not on the regular schedule. Green class lights, flags or markers on a locomotive indicate that there is a following section of this train. Red lights, flags, or markers designate the end of a train (somewhat like tailights on a car).

There are fixed signals, those that don't change position relative to the railroad. Among these are block signals, routing indicators, and switch stand markers. Routing indicators are illuminated signals that indicate the position of points on switches (typically on electrically or pneumatically operated turnouts). These often are seen as a group of white lights in a small housing. Switch stands may either be metal flags or lamps that indicate the position of the points. At the IRM, a yellow-painted flag indicates that the switch is a spring switch. Alternatively, a small white oval plackard with "SS" may be used to indicate such a device, called a "mouse trap" by many of our crews. For switches that impact mainline operations at the IRM, there are signals that work in conjunction with the block signals providing "point protection." These signals can be seen at greater distances and allow for safer operation at speed.

Whistles and gongs on street cars are also signaling devices. Examples of other non-fixed signals include those hand signals between crew members and brakemen/switchmen, and communicating signals between conductor and operator on trains appropriately equipped. (A future web page will explore hand signals in use at the IRM.) There are signals for the public, too, at most grade crossings: flashing lights, crossbucks, or bells are common, and may be combined with automatic crossing gates.

In addition to all of these signals, operating indications may be provided to the train crew via radio by either the dispatcher, other train crews, or crew members on the same train. Railroad dispatcher orders for a train may sound like this at the IRM:

"CB&Q 9911 East has permission to depart on a standard trip at 13:15 hours. Eastbound meets are as follows...IT 1605 West at East Station Switch, North Shore 160 West at Johnson Siding. Westbound meets are as follows...Meet CTA 1412 East at Johnson Siding, following that meet proceed West to Schmidt Siding and meet J. Neils Shay #5 East bound at Schmidt. Following that meet, hold Eastbound in Schmidt and meet CTA 1412 West. Following meet with CTA 1412 West, return to Station Track One, that is O N E. Over."

The train crew on 9911A will then repeat the order to the dispatcher. Following that repeat, the conductor will confer with the engineer to ensure that the orders were received and understood by both parties. Such detail and coordination is essential, especially for busy operating periods. the IRM has a one-track 4.5 mile mainline. At the recent Vintage Transport Extravaganza, the dispatcher for the day indicated that there were 45 trips made by trains on the mainline for that day! An average trip is between 35 and 45 minutes, and the operating day was only a bit over 7 hours long. That number of trains is possible because of the use of the block signals and a passing siding at each end of the railroad.