For VA 228, I used the LRS Route Master (https://www.virginiaroads.org/datasets/VDOT::lrs-route-master/explore), which shows VA 228 deviating from its original route through Herndon to the Herndon Parkway truck bypass. The re-routing was made as a recent request by the Town of Herndon.

As for SR 606, the route is (very loosely) signed on the ground at many major intersections as following all of Herndon Parkway, however the SR 606 designation does not show up in the Route Master. Often times, secondary state routes are not signed within towns, so this could be a case of outdated signage or an error on part of the Route Master.