Insulated track...

Better IMO to use a relay. If you have old tubular track,you have to take it apart and insulate the outer rails. using relays with the outside insulated rail is described here

www.jcstudiosinc.com/BlogShowThread?id=410

Dale H

Here are some pictures of isolated/insulated outside rail sections. Atlas track



Gargraves track with Ross switches.

Dale definitely has the right idea. The Pressure plate?  Well, it is a barely satisfactory mid 20th century way of doing it that just doesn't work that well compared to modern ways.  Relays (electronic or electro-mechanical if need be) are the way to go.  some track manufacturers, like Atlas, make track connectors out of plastic that are made to isolate sections and yet provide no crack or gap for the wheels.  but the method shown above works well, too.

Insulated rails and relays are the way to go; however, if that seems daunting to you, or like I, have forgotten to install an insulated rail during a layout build, you can always use a Lionel #153IR detector or the MTH equivalent device.

Really simple!  At the bottom of this page, Switches, Page 1 is how to make a track trip.  This works for momentary activation and doesn't even require an insulated track sections.

Uhh... Susan?  That link takes you to an America's Cup race video!

Boats are fun, but not quite on the current topic.

Oops, thanks for the catch on the url link (corrected).  That's what I get for double tasking.

Now we know you like boat racing.

Marx used to supply those with some simple operating accessories, such as the bell-ringing crossing signal.  They will give you a short pulse whenever a wheel is present. To use them to make a reliable activator you need two of them in conjunction with two relays. One track thingie  to operate the first relay, which holds on its own windings, and a second track thingie to operate the second relay, which knocks down the holding path of the first relay, and holds the accessory operated until the last car clears the block. In this way, using just two relays, you can eliminate the concern of train length. Every train, whether short or long, will operate the signal the same way.

The usual caveats apply: Use DC and use slow-release relays (with capacitors).