The railway radio communications system consist of base stations (called "towers") that are located every 20 or so miles along the right of way. Each base station consists of the radio hardware located in a shed of some sort, a tower and antenna, and the means to communicate with RTC (either via landline or point-to-point microwave. 

All railroad radio activity takes place between mobiles in locomotive engines, crew with walkie-talkies and mobile equipment in road vehicles. Communications with RTC only takes place when one of the operators "keys the tower" - by transmitting specific tones on the frequency to activate the link to RTC. You can tell when RTC 'comes on-line' by the  data transmission on the channel, which sounds like a standard 'squawk', for those who are familiar with radio communications. RTC doesn't, as a rule, monitor every transmission that takes place on the system.

MOW (Maintenance of Way) bases are linked together so work gangs can talk to each other over the whole length of a subdivision through a network of passive repeaters. In remote sites, such as in the mountains or in the barrens of Northern Canada, railways use repeaters on their mainline channels -  this is only done where train crews need to talk to each other over long distances or where the environment makes standard radio communication impossible. Main channel repeaters are not used in the GTA's rail lines.

The following is a complete (at least as complete as I could make it) list of CN Transmitter sites in the GTA and beyond (I went as far west as Hamilton due to the popularity of Bayview Jct and the surrounding area). Some sites are transmit sites, others are merely detectors (Its impossible to tell with just the TAFL listing.) Typically, a detector would only transmit on channel one, so I've assumed that channel-one only transmitters are detectors and highlighted them as such. Some, such as the one at mile 18.1 of the Halton sub, I know are detectors. If you see an error or would like to make a change or addition, get in touch and I'll see what I can do.

There are also 'minor' transmitters located lineside, such as automatic derails and the like. I have not listed these, but there are such items at all major yards (Mac yard, BIT, Malport, Oakville Yard, Aldershot, Hamilton, etc.)

Note - The Uxbridge, Newmarket and Weston Subdivisons have no detectors.


List of CN Radio Transmitter Locations in the GTA and vicinity
Source: Industry Canada Technical and Administrative Frequency List

Quick CN Channel Listing....

1 - 161.415	2 - 161.205	3 - 160.935	4 - 160.665
5 - 160.365	6 - 160.485	7 - 159.810	8 - 161.025
All sites transmit 161.415 MHz

City	Subdivision	Mileage	Sup.Chs
Newtonville	Kingston	278.5	1
Oshawa	Kingston	290.5	1
Oshawa	Kingston (Yard Office)	303.2	1,2,4,6
Oshawa	Kingston (CN Sig. Shop)	303.2	1
Scarborough	Kingston	320.4	1
Toronto	Kingston	330.3	1
Scarborough	Kingston (Scarb. Station)	325.2	1,5
Toronto	Kingston	"Don yard"	1,2,4,5,7,8
Toronto	Kingston	ScarSigShop	1,2
Bowmanville	Kingston	290.5	1,3
Markham	York	12.2	1,2
Ajax	York	7.7	1
Fisherville	York	21.6	1
Stouffville	Uxbridge	40.6	1,3,4
Brampton	Halton (Intermodal Term)	8.9	1,4
Brampton	Halton	18.2	1
Milton	Halton	36.6	1
Mississauga	Oakville (Port Credit stn.)	12.8	1
Downsview	Newmarket	9.5	1,2,4,5
Aurora	Newmarket	30.2	1,3,4
Toronto	Oakville	6.7/Mimico Yard	1,5
Toronto	Oakville	5.1	1,8
Mississauga	Oakville	14.0	1
Burlington	Oakville	33.0	1
Oakville	Oakville (yard)	20.6	1,4,5,6
Hamilton	Oakville	39.3	1,3,4,5,6
Oakville	Oakville	21.4	1,2,3,5,8
Burlington	Oakville (Aldershot Radio Site)	34.6	1,5,8
Toronto	Weston (W. Toronto stn)	5.2	1,5,7
Toronto	Bala	4.9	1
Richmond Hill	Bala	31.0	1
Maple Beach	Bala	60.0	1
Udney	Bala	78.5	1
Vandorf	Bala	?	1,2,5,8
Vaughan	Maple Hump Yard	n/a	1,2,8
Vaughan	Macmillian Yard	n/a	1,2,5,8
Toronto	TTR/Union Stn. Area	277 Front st.	1,4,5

Quick Canadian Pacific Channel Listing....

1 - 161.475	4 - 161.115	5 - 161.325	7 - 161.535
82 - 160.815

City	Subdivision	Mileage	Channels
Lambton	Galt	5.8	1
Lambton	Galt	7.4	1
Toronto	Galt	0.0	1,4
Toronto	Galt	5.1	1,4
Mississauga	Galt	25.0	5
Mississauga	Galt/Owen Sound	20.3	1,4
Milton	Galt	31.2	1
Milton	CN Owned		1,4,7
Kinnear	Hamilton	55.4	5,82
Smithville	Hamilton	37.3	5,82
Flamborough	Hamilton	71.2	5,82
Smithville	Hamilton	44.9	5
Hamilton	Hamilton	57.5	1
Welland	Hamilton	20.4	82
Agincourt	Belleville/North Toronto	n/a	4
Scarborough	Belleville	200.4	1,4,7
Bowmanville	Belleville	164.6	7
Bowmanville	Belleville	164.6	7
Whitby	Belleville	? w of 195.0	7
Toronto	Belleville	206.3	1,4,7
Toronto	Obico	9.6	1,4
Havelock	Havelock	93.7	1
Agincourt	Havelock	180.3	1
Agincourt	T.O. Yard Diesel Shop	n/a	4,7
Oakville	CN Owned		1,4,7
Essa	Mactier	35-40?	4,7
Palgrave	Mactier	30-35?	4,7
Alliston	Mactier	48.9	7
Bolton	Mactier	25.5	7
Emery	Mactier	7.8	7
Vaughan	Mactier	15.3	7