Need to clarify "impossible to run a train off the table (removable clear barriers, which also let you control the access of the little fingers of the littlest ones)"
The table is against one wall; the other 3 sides are accessible. There also is a "Y" shaped 24" wide internal walkway, accessible from the bottom of the Y. Of all the open edges, walkway and outside, perhaps 2/5 have the barrier - only where running off the table is a risk.
The barrier is clear plastic, mostly 36" lengths, in a slot at the table edge. Plastic is 6" wide; about 4" shows up; 2" are in the slot.
3 of 4 kids (ages 9, 11, and 13) can and do remove barrier sections as they wish. Mostly they just reach over the 4" - their choice. A barrier section is frequently lifted (by one of the older 3) when an operating accessory is misbehaving or needs some help. Only the now-5-yr-old does not have the finger strength to remove a barrier section. There is a spot on the table where she likes to play with the figures; the barrier is usually removed there for her. But when she leaves I know that that is probably the only place that I have to really check for items on the tracks.
With the barrier, the kids run the trains as fast as they wish and do not worry about damaging the trains. Them not worrying is as important as me not worrying. (And the barrier has kept my wife and the kids' parents from worrying - also important.) The 11 yr old boy sometimes really lets a train run as fast as it can; no worry. By the way, except for two corners in one loop, all the outside track is 42" or 54" diameter O-27. A derailment from speed only has occurred with a naked engine.
