(Today, the) TTC uses radio controlled switches. In the era of PCC cars overhead contacts were used but given that the TTC now has three lengths of streetcars this is now not possible. On the dash of the streetcar there is a NA button. NA stands for Necessity Action Switch a system that dates back to 1945. It requires positive action on the part of the operator whereas standard street railway switches are power on or power off allowing occasional unintentional switch throws.
When the NA button is pressed the front antenna emits a signal. The signal includes the streetcar number. The signal is picked up by a loop buried in the pavement between the running rails. The loop sends a signal (via wire) to a controller on a wayside post.
The controller includes a memory chip, which records all switch activity: each streetcar number crossing the switch, whether the NA button was depressed or not. Using a computer the speed of the streetcar can be determined, which direction it was traveling or if the direction changed (i.e. forward then reverse as in doing a wye).
The controller interprets the signal and then sends a signal (via wire) to the switch engine either to move or to stay in its current position. NOTE: If you turned at this switch on the last trip, the controller will try to send you on that path.
A rear antenna constantly emits a release signal. It is received by an exit loop buried in the pavement between the running rails. The loop sends a signal (via wire) to the controller on the wayside post. The controller interprets the signal. Then stores it in the memory chip or board. The controller sends a signal (via wire) to the switch to unlock it so that it will accept the signal from the next streetcar.
As all switch elements are exposed to the elements, the radio control system is not considered a vital system and switch position must be visually confirmed at a speed where the streetcar can stop before entering the switch.
NA switches are indicated to the operator by a
NA --> sign with a small arrow indicating the direction of turnout.
Photo source:
http://transit.toronto.on.ca/streetcar/4502.shtml
"A close-up of a dashboard of a rebuilt all-electric PCC. The switches are, from left to right: NA activation (unlabeled black button in top left corner. It activates track switches), gong, sander (releases sand for better traction), signal bell, front doors open, M-G set (power system), treadle switch (allows passengers to open back doors by standing on steps), EM reset, headlight, defrost fan, center entrance (opens back doors outright), cab heat, advance lights (green light up top and other non-headlight lights in front), lights (interior), lights (interior, second set)."
In a age of budget cuts automatic switches do not always work. Then the operator has to get out of the streetcar and manual throw the switch with a switch iron. All TTC streetcar switches are single point switches where is only one moving blade. Railway switches typically are double point.
IMPORTANT: Any operator manually changing a turnout must restore the mainline to its original state before proceeding.
In addition to the Necessity Action Powered switches you will find SR or self restoring switches which usually are spring switches on the second leg of a 90 degree turnout.
