Direct Traffic Control Explained
Direct Traffic Control (DTC) was Southern Pacific's version of dispatching trains via radio, introduced in mid-1984. SP originally intended to try out DTC on the Carrizozo - El Paso portion of the Tucson Division's Carrizozo Subdivision, and the first instructional booklet reproduced here reflects this. Instead, DTC premiered on the Tucumcari - Carrizozo portion of the Sub, which was experiencing near-gridlock under the traditional train order system.

DTC turned out to be a sound method of getting trains over the road, and the original setup explained here didn't change very much over the years. Beyond being an efficient system (when the radios worked), it was very easy to grasp, in contrast to the vagaries of train orders (see A Train Order Primer). After studying this booklet, you'll know as much as we employees did on DTC Day One.

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NEW 5-19-2019!
Entire booklet as a PDF

T&E crews kept track of their block authority in tear-away pads, an example of which (handily labeled "EXAMPLE") was contained in the booklet (below). We have no idea if it portrays the actual block arrangement that SP later used on the line below Carrizozo.

Further below are two clickable thumbnails which show an interim DTC pad created by an employee, and the company version which didn't show up until DTC was already well under way.

SP Pages
Jawbone Dispatching
A Train Order Primer