I have never seen it but I have heard of it.WB traffic is posted at 40MPH in S.San Diego.Once you hit the welcome to IB sign it is 35MPH.The catch is traffic is going around 45,50 and the light at 13th Street and IB Blvd can be a long one.So people tend to speed up racing the yellow light.Now you are going about 50,55 MPH in a new 35MPH zone.But traffic heading EB on IB Blvd starts off at 40 MPH once you cross 13th street.Now tell me that makes sense?Sounds like a Imperial Beach ticket trap to me .