Sure, track power will work for track switches, but adjustments to the throttle will affect track power (and thus the speed of the locos) and also the performance of the switches. If you intend to install TMCC, then 18 volts will be constantly directed to all the rails and switches. The switches would work fine with just 14v connected to them. Further, by providing a separate power source to the switches you "give back" some electrical headroom from a 180-watt "brick" to the locos and operating accessories.
Many hobbyists add bigger and power-thirsty loco to their collection as time goes forward; in which case consider placing a second 180-watt "brick" in the track circuit then, if not sooner, to provide twice the wattage for locos. Lionel makes a wiring connector for that purpose.
I "second the motion" of the responder who suggested adding a reversing loop. Watching trains running in circles may soon become monotonous and boring.
Carry on, regardless ...
Mike Mottler LCCA 12394
