A conductor operating on a line with Automatic Block Signaling (ABS) observes a yellow (approach) signal followed by a red (stop) signal at the next location. Under ABS rules, the crew must:

1. Proceed at track speed past the yellow, then stop before the red signal
2. Begin reducing speed at the yellow signal and stop before the red signal, or at the red if it clears to permissive
3. Proceed past both signals at restricted speed since ABS signals are advisory
4. Contact the dispatcher before passing the yellow signal