The study, in which state police participated, recommended limiting the locations where drivers can move in and out of the HOV lanes in the hope that compliance would lead to better travel times. Drivers are seeing the results of that recommendation in these double lines, marking the areas where there should be no lane changes. It’s a work in progress. Still to come are signs that read “Do not cross double white lines.” The gaps in the solid lines at certain locations are there to allow traffic to enter and exit the HOV lane, according to Randy Dittberner, VDOT’s regional traffic engineer.