Scanner Radios & Frequencies
Many people have asked us about the use of radios by railroads and how riders and fans can use scanner radios to "listen in". This section of ON TRACK ON LINE discusses these topics.
AAR Channel Numbering System
The American Association of Railroads has assigned channel numbers to each of 96 radio frequencies in the 160-161 MegaHertz bands. These frequencies are used in the United States and Canada. Channels 7-96 are used in the U.S. for railroad operations. Channels 2-6 are used in Canada for rail operations only. In the U.S. channels 3-6 are used by railroads for truck operations.
The following table converts from AAR channel number to the appropriate radio frequency (MHz).
Note that these frequencies are not the only frequencies used by railroads. Some railroads also use frequencies in the 4xx.xxx MegaHertz band, particularly around 45x.xxx, 46x.xxx, and 47x.xxx.
Most official railroad radios that synthesize the frequencies have a window that shows the AAR channel number for transmitting and the AAR channel number for receiving. For example, Amtrak's primary Road frequency in the Northeast Corridor is 160.920 MHz, Channel 54. The window on the railroad radio would show 5454 (transmit on AAR channel 54 and receive on AAR channel 54).
Railroads also use some frequencies to transmit end of train telemetry. Some EOT devices, for example, transmit the train's brake pressure to the closest tenth of a pound and whether the EOT is moving or not every 40 seconds or whenever there is a change. AAR has allocated 457.9375 MHz and 452.9375 for EOT telemetry with the latter used at the head end to transmit control signals. Most railroads use these frequencies.
Since EOT devices transmit at two watts, the transmission will travel about 3 to 5 miles. Thus, by setting your scanner to scan these EOT frequencies, you get a warning whenever a train approaches. The problem with this strategy, of course, is that as soon as your scanner picks up anything on 457.9375 or 452.9375, it will lock on that channel. Thus, this strategy works best if your scanner makes it easy to change the channels that are scanned so that you can stop scanning 457.9375/452.9375 when you know a train is close.
Using a Scanner Radio
When you use a scanner radio to listen to railroad frequencies you will hear:
Some methods for using a scanner radio:
Once you've used your scanner for a while, you'll think of other methods.
Hint: Use an earphone or earphones. It's much easier to hear your scanner with an earphone, and if you are traveling on a passenger train an earphone is required.
LAWS: The use of scanner radios is governed by federal laws and regulations, and various state laws. A summary listing can be fouund here. The details can be found at the Scanner Reference Laws, Rules and Regulations web site.
Selecting a Scanner Radio
Here are some features to look for when selecting a scanner radio for scanning railroad frequencies:
Number of Channels
Scanners are available that have 10, 20, 50, 100, 200, 300 and even more pre-storable channels. These are internal channels that the user can select and punch a frequency into, after which the frequency is permanently stored in that channel (until you change it). The more channels the more expensive the scanner, of course.
For railroad scanning, 20 scanner channels is usually adequate, but 100 scanner channels is much more flexible since then the 96 AAR frequencies can be pre-set, as discussed in the Using a Scanner Radio section. 200 channels adds even more flexibility as the 96 AAR frequencies can be pre-set, and other banks of frequencies for particular areas can be pre-set, including areas that don't comply with the AAR scheme (several transit systems, Canadian railroads, FRS channels).
The primary brand names for hand-held scanners suitable for scanning railroad frequencies are Radio Shack and Bearcat, both made by Uniden America Corporation. In general, the Radio Shack models are more expensive, but there are far fewer stores that carry Bearcat scanners. Bearcat scanners are readily available by mail order however. Other brands can be found at electronic supply outlets also.
The best scanner radio that money can buy is worthless without an antenna. But often the antenna that comes with the scanner (usually called a "rubber ducky") is hardly better than no antenna, particularly inside a steel vehicle or in an area of poor reception such as a city, valley, dense forest, and so on. The best way to improve the performance of your scanner is to improve the antenna you use.
Although convenient to use, rubber duckies and base station whips are short, not optimized for railroad frequencies and cannot be moved to the best position without moving the scanner. Longer antennas, adjustable whips, and (for indoor base units) a wall-mounted antenna can be a major improvement.
Rubber duckies are actually "loading coils" -- a coil of wire used to effectively lengthen the electronic length of an antenna without increasing it's physical length. The electronic length of an antenna is critical to it's performance, but only a variable length antenna is correct for many different frequency bands. So one important improvement over rubber duckies is an adjustable whip, usually with a small loading coil near the bottom. Antennas of this type which will connect directly to scanners are available at Radio Shack and many electronic supply shops.
To tune an adjustable whip the following formula governs:
Let's look at the former Conrail's main road frequency, roughly in the middle of the railroad band:
So, a 17.4 inch antenna will optimize reception (anything within about 1/2 inch will do). Note that this is a "quarter-wave" antenna -- one quarter of the wavelength for that frequency. This quarter-wave 17.4 inch antenna will work pretty well across the entire AAR Channel range listed above.
If your antenna isn't adjustable, you can get the same result by trimming or shortening the antenna with wire cutters. Be sure to measure carefully! Usually you can cut from the bottom of a fixed length antenna, depending on how the bottom is configured. Sometimes it's only feasible to cut from the top. Some sort of protective item should be attached to the top in that case. It will have little effect on performance. A styrofoam ball glued on is one possibility.
Another thing that can be done to improve performance is to use a "ground plane". Actually the antenna one sees is only half of a true antenna. An electrical ground is the other. Without a ground an antenna cannot work well; with a ground plane the improvement can be considerable. Good ground planes are:
For a portable scanner, the best that can usually be done is to position the scanner on a metallic object such as an vehicle hood or roof, roadside guardrail, or pipeline standpipe. The latter is probably best since it makes the best electrical ground. Obviously the scanner should be removed from any sort of leather/leatherette case. The plastic case of the radio reduces the effect but doesn't eliminate it.
There are several sources for lists of frequencies used by North American railroads.
Amtrak trains use the frequencies of the Host Railroad over which they are running. Our Amtrak Frequencies Page lists the frequencies Amtrak uses on each of its routes.
Family Radio Service Channels and Frequencies
FRS is a private, two-way, very short-distance voice communications service for facilitating family and group activities. FCC license is not required. Amtrak On-Board Service personnel will be using this system on some trains. Frequencies will be taken from the following authorized list, with no prior frequency assignment. Most scanners are capable of receiving these frequencies.
Also learn about the use of a Global Positioning System (GPS) receiver on a train on our GPS Train Tracking page.
For more information on this topic or to make suggestions for additions or corrections to this page, you may contact