VDOT CG-9D Apron Detail

This Springfield, Virginia project added a second apron to the property, built to the VDOT CG-9D detail. Second aprons are always a challenge: VDOT's access-management policy generally allows one entrance per parcel, and the NOVA district has grown reluctant to approve second (circular-driveway) aprons, so approval is case-by-case and has tightened in recent years. This one required special plans, and the permit took about six months to secure. The project also included drainage work, a concrete driveway and two walkways.

Built to the CG-9D detail

When VDOT issues the land use permit, they are authorizing us to work on state property, and the standards for the apron are significantly higher than the standards for a private driveway. A standard residential driveway is typically 4 inches thick. A VDOT apron built to the CG-9D spec used in Fairfax and Prince William must be a minimum of 7 inches thick. We use VDOT Class A3 concrete (min 3000 PSI), or the jurisdiction's mix, and we typically upgrade to a 4,000 PSI air-entrained mix. We install VDOT #21A crushed stone to the depth the entrance standard and permit require, compacted in lifts, and we reinforce an apron only where the jurisdiction's detail calls for it.

The bond release

Posting the surety is easy; getting it back requires passing VDOT's final acceptance inspection. The disturbed ground around the new apron has to be restored and stabilized with established grass before VDOT signs off and releases the surety. We perform a rough grade around the new apron and backfill the edges with native soil so the ground is flush with the new concrete; the client is responsible for final restoration, applying topsoil, seed and straw and watering the grass in.