I didn't know their was such a thing. Do you know what it's called?
Since you asked, there are several on the DLS. There are three updated for TS2010. They all help guide the placing of other tracks. The first and third don't have any other attached track, you line up the other tracks visually. The second has five tracks that start as invisible and only change when you attach another track.
guide 5t 4m spacing 70337:23015:2
Guide 5t 4m with track 70337:23001:2
Guide 5t 5m spacing 70337:23002:4
The black rings are guides to place overhead power wires, aka catenary.
There are also some older guides made for TRS2004 that I still find useful. They have different track spacing (3.5, 4 and 5m) and different number of tracks, 2, 3, 4 and 12.)
Guide 12t 4m 16m 70337:23096:2
Guide 2t 3.5m 70337:23089:2
Guide 2t 4m 70337:23083:2
Guide 2t 4m 16m 70337:23094:2
Guide 2t 5m 70337:23086:2
Guide 3t 3.5m 70337:23090:2
Guide 3t 4m 70337:23084:2
Guide 3t 5m 70337:23087:2
Guide 4t 3.5m 70337:23091:2
Guide 4t 4m 70337:23085:2
Guide 4t 5m 70337:23088:2
The push pins are invisible in Driver. The invisible tracks change to whatever track you attach to the guide.
A few are shown to the right of the new ones.