Existing SR 400 has generally four non-tolled general purpose lanes in each direction from MARTA North Springs Station to McFarland Parkway and three general purpose lanes north of McFarland Parkway.

The SR 400 Express Lanes project would add two priced express lanes in each direction from MARTA North Springs Station to McGinnis Ferry and one priced express lane in each direction from McGinnis Ferry to just north of McFarland Parkway. Additional lanes are required intermittently along the corridor for either general purpose or express lane access points or for potential queuing BRT stations as well as the collector-distributor lanes. Within the SR 400 Express Lanes project limits and upon project completion, SR 400, in general, will have between eight and 10 travel lanes in each direction (express lanes, collector-distributor lanes, and general purpose lanes). Although in some locations the number of lanes increases to allow for access ramps and connections to other roadway facilities, for example connecting to I-285 near the North Springs MARTA Station and to allow for BRT access to MARTA’s Windward Parkway Park-and-Ride.