Off of the 57 fwy in Brea, CA there are 4 poles with red lights in the foot hills. What are they for?

Answer 1

Difficult to say without a more precise description or a photo. How tall are those poles? Are they strobe lights? Could be antennas, maybe cell phone antennas, with a warning light for planes. Or part of a Approach Lighting System (ALS). Is there an airfield nearby?

On the Toppgraphical map there is an indication "Radio Towers" about halfway between Brea and Carlton, about 1 mile East of the freeway. That it?

http://www.topozone.com/map.asp?lat=33.92334&lon=-117.88892&datum=nad83&u=4&layer=DRG100&size=l&s=200

Answer 2

for flight pilots to see while they are flying to keep them from flying too low or hitting the mountains.. sometimes at night it is hard to see especially in the mountains when you do not know their altitude, those poles keep them from flying near the ground/mts.