Around the room ceiling loop?

I wouldn't say a guard rail is an absolute necessity.  When I build mine there won't be one.  And it seems most that I've seen in person or online don't have one either.

raising4daughters,

I will try to dig up my photos of my ceiling layout. It was two individual loops of O72 and O81 with no guardrail. I had no switches and never had anything derail. It was decorative wood brackets screwed into the studs and 1x8's that were glued to the brackets. Super strong. 

raising 4 daughters

A regards guard rails, I used 1/8" plexiglas x 2-1/2" high[cut in strips by Lowe's]. However over 16 years on twin shelves 14x32, with 5 tracks and much run and display activity I never had a derailment that came anywhere close to hitting the plexiglas fence.

I ran a 4-6-6-4 Clinchfield Challenger with 30 coal hoppers on the upper track of the 9' high shelf and on several occasions the first 8-10 cars "stringlined" upon entering a curve,uncoupled and tumbled over. I eventually weighted them which fixed the problem. But my point, none of the cars ever came down the stepped tracks and hit the fence.

A lot of folks ,including my 4 Grand Daughters, ran my trains fast but fortunately derailments were not severe wrecks or trains-to-fence/floor.

[Old photos-shelves dismantled in'08] 

Thanks, especially for the pictures.  The decorative shelf brackets look like a great idea. I'll definitely go with that.  And, I really like the idea of elevating the rear loop so it's not hidden by the front loop.

On the three ceiling layout I have built for people, I mention to them that if they are going to be 8 inches to a foot from the ceiling, with two lines, I suggest raising one of the lines with a 2 inch thick piece of styofoam on the back loop and a 1/2 inch on the front loop.  If they have the room over doorframes and such, I reccommend 12-14 inches so that the scenery papers fit from shelf to ceiling.  I never use screws to hold the track in place.  I use zip-ties(cable ties) it takes two for each track.  I use very small ones, usually black, and I place one down through the hole in the track and the othe from the bottom of the board.  This reduces the transfer of sound, and makes it very simple if you happen to have a piece of track go bad.  You just clip the cable tie, remove the bad track, replace, and install two cable ties.  You are not up in a confined space screwing screws.  The final suggestions are on my layouts if I had two corners that could be dropped, it creates a great scenery area of focus...trestle bridge, viaduct, ravine, autos going through tunnels and lights etc. to draw attention to the upper loop.

These layouts have made my customers very happy and I agree, you do not need to worry about guard rail.  both layouts I did had legacy, TMCC, or DCS so they ran long consists at a fairly slow speed.  I don't think that there has ever been a derailment.

My shelf layout is about 12" from the ceiling althou just single loop I put the green indoor/outdoor carpet on the underside and part of topside of the layout so from underneath it looks better than just thye plain wood. I do not have guardrails my thinking if its going to jump any direction it would be inward most likely. 

If you goto this link it will take you to my shutterfly page and you can see over 800 real train pictures ( I normally goto slideshow full screen and have some music on  also you will see links to see my shelf layout there now these are old video's this was using O-31 track I now have O-54 up there. the one that feels like your driving I put a cheap lionel 7" flat in front and rubberband my camera onto that. again these videos are about 3 or 4 years old. https://rtssite.shutterfly.com/