Foam roadbed, what's the state of the art method?

A friend is building his framework and planning on using extruded foam as the flat top.  Dips and rises will be worked in later after the flat track is laid.

Obviously the profile has to be built up for drainage etc so cork could be used but is it used alone or are there any alternatives to keep noise down?

Mark in Melbourne

Having trouble getting headlight to work.  Had to place the green wire on the empty pin for the mars light which works fine.  Digitrax could not advise any further.  Has any one had this problem and if so what is the solution.

I have a PSX-AR Auto Reverser to power the reverse loop with the appropriate gaps and it is powered by a Digitrax DB150 Booster. On the mainline, with a RRampMeter and a taillight bulb clipped on as a load I get over 12 volts and 2 amps. When I test the loop I get no readings. But when I unclip the taillight bulb and just use the RRampMeter I get a reading of over 14 volts and 0 amps on the loop.

So I have a Wabbit - two hares - that I am planing to use to throw a turn out heading into a reversing loop so I can get continous running out of a loop to loop layout in N scale.

1.  I'm still not clear on how the triggering rail thing works, how does the hare know the engine has hit the trigger rail? What is detected?  I'm assuming the trigger has to be far enough away so that the tortoise has enough time to move.