The route is paved for its entire length, in contrast to some other state highways in northern New Mexico. It is 4-lane road from Pojoaque to the junction with NM 30, then adds a fifth lane west-bound to accommodate the heavy commuter traffic going from Pojoaque, Española, etc., to LANL in the morning, and back in the evening. The road narrows to two lanes beyond the junction with NM 4, where much of the LANL traffic leaves NM 502. NM 502 has been a designated "safety corridor" for most of its length since November 2005, with speed limits restricted to 55 miles per hour (89 km/h) maximum, and lower through the towns and on the steep curves near the intersection with NM 4. Prior to 2007, the speed limit along the stretch from San Ildefonso Pueblo and Pojoaque Valley High School was 65 mph.