Shortly after the Big Walker tunnel on a downhill stretch of 77 South. Could see police cruiser sitting on right berm of the highway probably a quarter of a mile ahead of me. Cruiser had lights on and waiting for me before I even came up on him. Actually unsure whether he was pulling me over or just attempting to get back on to the roadway. Decided I had better stop even though he hung back and never really pulled up behind me. Once I started pulling over he came up at a high rate of speed and questioned me as to why it took me so long to pull over. Never indicated how he clocked my speed. On return trip approximately 12 days later heading north on 77 near Galax and again in Bland county saw 5 police cars picking motorists off left and right. One cruiser actually was heading south and flip flopped in median to grab a northbound vehicle. Unsure how he could possibly have clocked that driver either. Big brother most definitely is watching from afar. No question is a huge speed trap! Beware.