I have a question regarding Runway distance remaining signs.Do these signs start and end measured from runway thresholds, or is distance remaining measured along the entire runway?

I could be wrong, but logic dictates they relate to the usable runway surface, excluding emergency sections like overruns.

The number on the signs indicates the distance (in thousands of feet) of landing runway remaining. The last sign, i.e., the sign with the numeral "1," will be located at least 950 feet from the runway end._____________________________www.BeechTalk.com

At Volk Field Wisconsin, an ANG training Base in the late 50s and early 60s, there was one additional sign. At the West end of the runway, adjacent to a marshland, the signs read 3, 2, 1, each in its approporiate spot, and then at the very end was a sign that read "You Bought The Farm."R-

Would this mean that a displaced threshold, like at KBIX, would be included as usable runway in relation to distance markers?

A displaced treshold is only for the landing runway, as the runway is not strong enough to support aircraft slamming down on it there or because the area in front of the runway is built up making the approach too steep.So it's not an overrun, it's restricted only in a single direction (and even then usually only for landings).

2-3-13. Runway Distance Remaining SignsRunway distance remaining signs have a black background with a white numeral inscription and may be installed along one or both side(s) of the runway. The number on the signs indicates the distance (in thousands of feet) of landing runway remaining. The last sign, i.e., the sign with the numeral "1," will be located at least 950 feet from the runway end.

>Would this mean that a displaced threshold, like at KBIX,>would be included as usable runway in relation to distance>markers?>>You don't specify whether you are asking about the displaced threshold of this end or the far end. Either way, the displaced threshold does not matter. The displaced threshold on the far end is usable for rollout. If you are standing on the runway and looking down the far end, a big sign with a "9" will mean there is 9000' left until the pavement runs out, even if you are standing within a displaced threshold. Asking about the displaced threshold which you just crossed over while landing is pointless, since it's behind you. The sign only relates to what is ahead of you. All that matters for that sign is how much concrete is left in the direction in which you are facing.