This section describes perhaps the 'most extreme' variation on the T-Trak theme. It abandons the 2-mainline paradigm (I've wanted to find a legitimate use for that word...) in favor of the 1-mainline paradigm (...and now I've used it twice!).
T-1-Trak uses modified Single and Junction modules to make transitions from double- to single-track and back again, and modules with a single mainline- either the outer or inner main.
There are 2 single to double variations-- one makes the transition from double-track to the outer mainline, the other to the inner mainline. The use of one or the other depends on the needs of the layout in question.
The modified junctions allow the two mainlines to split and follow separate routes. The inner main follows a curved path, and runs at 90 degrees from the mainlines. The outer main continues straight, and a turnout splits the main into a double track (or a passing siding).
This basic layout shows two possibile orientations of the modified junctions. The first shows a passing siding occupying most of the left end; the second a small, inner circle.
At the top of either example, two 2-to-1 transition modules merge the mainlines to the inner main. At the bottom, two transitions merge the mainlines to the outer main.
This more complicated layout shows a point-to-point layout. Standard junction modules form return loops at either end. The return loops have small 'round-and-round' circles inside the loops. The loops do have an "S" curve at the tips of the junction modules.
Modified Junction modules split the inner and outer mainlines along separate paths. If additional straight modules are inserted along the outer red mainline (between the corners and the modified junctions) the two mainlines can be spaced farther apart, requiring additional tables.
Nathan M. has created another T-1-T modified junction he calls C-Junctions. They appear to be built on a somewhat modified double alternate corner. From the description of the track pieces used, the base should be 3mm less than 12.7" wide, and extend across the table-- 28-3/4".
The inner main follows a U-turn curve, and the outer mains continue across the module and a turnout splits them into a double track again (suitable for a passing siding).
A 'newly discovered' collection of "mini-T-Trak" modules, with a single-track mainline, can be an interesting addition to a single-track layout.
The modules are full length, but only 150mm (6") deep. Modules are 100mm high (the original maximum operational height). One of the drawbacks of this design is that it does not include a height-adjusting means-- there is no means of adjusting for tables of varying height, or modules that are not quite 100mm high.