Misc. Ramblings----Optimistic Speedo

[LarryIII]

Many of you who live in the Phila. area know that construction season has started on the Blue Route (I-476). I take that road every day to work in SVXY. On the northbound side, they have blocked off the right hand lane so we go from 3 to 2 lanes in a 'cattle chute'. The speed limt is 45 mpg thru this zone and there is one of those radar signs which flashes your speed just as you enter the 'cattle chute'. I usually pass it around 5:00 AM and the road is emty. I have been using it the last 2 weeks to test my speedometer. It seems that my speedo in SVXY is 2 mph optimistic. When I am exactly at 50 mph the sign flashes 48. Like at 70, the sign flashes 68. This morning I was at 60 and the sign flashed 58. I always thought that speed error is a fixed percentage so that as you go faster the variance increases. Either the sign is off or my speedo is off. Next week I'll increase speed to 80, 85, then 90 mph, conditions permitting. I'll report back my findings. I just hope that they don't put cameras on the the sign.
PS: SVXY has stock rims ad tires.