I-495 Express Lanes Northern Extension (495 NEXT) | Traffic Engineering, Utility Coordination & Construction Support in Northern Virginia
The I-495 Express Lanes and 495 NEXT projects represent major investments in modernizing one of the Washington, D.C. region’s most congested corridors. The original Express Lanes initiative addressed complex interchanges such as the Springfield Interchange and I-66 Interchange, where PSI provided critical traffic engineering support amid tight right-of-way and challenging ramp geometries. PSI developed and reviewed temporary traffic control plans, evaluated lane shift patterns, and coordinated construction staging to ensure safe vehicle movements through active work zones.
Across the corridor, 58 bridges were impacted – 29 demolished and rebuilt, 11 newly constructed, and 18 widened or retrofitted – requiring strategic phasing to maintain traffic flow. As the Express Lanes expanded into Fairfax County under the 495 NEXT project, PSI continued its involvement by supporting the addition of two new express lanes in each direction and the replacement of nine bridges. PSI’s traffic engineering expertise enabled seamless transitions between new and existing roadway segments, particularly in high-volume merge areas.
PSI also oversaw utility installations, including water, stormwater, electrical, and communication systems, and conducted field inspections in coordination with VDOT and contractors. Their teams monitored erosion and sediment control measures, enforced compliance with traffic management plans, and maintained detailed inspection logs, photographs, and sketches. PSI’s multidisciplinary contributions helped minimize disruption, enhance safety, and support the successful delivery of a high-capacity express corridor designed to meet growing regional travel demands.
