Increasing train speeds meant something to the Milwaukee Road, and the Feds. In the late teens, a few years following the completion of the mainline to the Northwest Coast, the railroad was required to invest in a signalling system to maintain its increasing passenger train speeds. The signals selected were some of the first to successfully use new lens technology that focused the lights for long distance viewing. Called "Type R" signals, these Automatic Block Signals (ABS) were manufactured by US Switch and Signal and remained in operation along Lines West from their installation to abandonment.
Near Lennep, MT these Type R ABS devices were in continuous use from 1917 until 1980 when the rails were pulled and vandalism began to take its toll. The original investment for the signals that spanned Harlowton to Lennep was $72,173.31 as reported in November 1917. 96 years have passed now, and the equivalent (inflation adjusted) 2013 dollars is $1.3M. Clearly, speed meant something to the Resourceful Railroad. Similar investment was taking place all the way west, wherever passenger trains plied the rails.
Interestingly, this did produce one left-over piece of unsignaled mainline. Known as "dark territory," the mainline went dark from Plummer, ID to Marengo, WA. Passenger trains left the main at Plummer and veered north to Spokane on joint Milwaukee-Union Pacific trackage. They rejoined the Milwaukee main at Marengo.
This is another one of the places along Lines West where it's easy to imagine the orange and black of the old railroad splitting the signals. The remains of these Type R's dot the old mainline through this section of Montana. They cast an eerie, industrial shadow of times past out across the modern day. Where a high green signal used to welcome the mighty electrics and diesels of years ago, sky blue now stares unrelenting down the old right of way. As Mr. Fred Hyde has observed, these are lasting gravestones of the Milwaukee Road.
Rest in Peace.