MAX signals

If you are looking for more information on the types of signals used by MAX light rail trains in Portland & surrounding areas, this is your starting point.

Discussion about signals has spanned several posts because MAX uses several types of signaling systems, so here’s a consolidated index of links to help you find what you are looking for.

ABS Signals (Automatic Block Signal System)

ABS Signals Part 1: An introduction to blocks, signals, aspects, and indications.

ABS Signals Part 2: Builds on the information from Part 1, explains route indications

ABS Signals Part 3: How the signals are numbered, map of ABS territories

Pre-Empt Signals

Pre-empt Signals: Overview, explanation of pre-empt aspects and indications, map of pre-empt territories

Standard Operating Procedures to proceed when a permissive aspect is not displayed

ABS/Pre-Empt Combination Signals

ABS/Pre-empt Combination Signals: Overview, explanation of route indications, locations of where some of these signals are used.


Dwarf Signals and C-Signals: Dwarf signals protect mainline power switches when trains are running reverse traffic in ABS territory. The C-signal sort of functions as a relay to let operators know their call went through at Skidmore Fountain westbound, since the pre-empt is not visible from the platform.

3 responses to “MAX signals

  1. So I was coming home today and spotted something I didn’t know what it’s purpose was. Was west bound, just before Beaverton TC on the corner of the east bound track was a single signal with a red only aspect on it which was lit. Is this signal for when trains have to run backwards on the track? Or is it because of the blind corner or….?

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