Usually a track block or loop can be as large as 90 to 100 ft and still operate O.K. The two variable channels on the TIU can be set to fixed, which allows for four DCS fixed signal systems.
With our larger modular layout, (Fort Pitt Hi-Railers), we split two loops. Use (2) Track outputs off the DCS for one loop, (1/2 the loop clockwise, Fixed #1, 1/2 the loop counter clockwise, Variable #1 set to Fixed). The loops are simply unplugged at the half-way distance. This reduction in total track length per DCS channel is a relatively easy fix, may be a first step in solving your problem. Input to the TIU Fixed#1 and Variable #1 is the same Output from one side of a Z4000 transformer.
