The Surface Transportation Board (STB) has officially approved Union Pacific Railroad’s proposal to construct and operate a new six-mile branch line in Maricopa County, Arizona, marking a significant step forward for rail-served industrial development in the Phoenix metropolitan region. The decision, issued in mid-March 2026, grants the railroad authority to move ahead with the long-discussed project following completion of environmental review and regulatory evaluation.
Project Overview
The new line—often referred to as the Pecos Industrial Rail Access Train Extension (PIRATE)—will extend approximately six miles from Union Pacific’s existing Phoenix Subdivision. Its primary purpose is to connect the main line with industrial properties located southeast of Phoenix-Mesa Gateway Airport, within the rapidly expanding Pecos Advanced Manufacturing Zone. One notable customer will be the Commercial Metals Company.
This area has emerged as a major hub for advanced manufacturing, with industries ranging from chemicals and metals to plastics and electronics. Until now, these facilities have relied almost entirely on trucking, as the nearest rail transload facility is located roughly 40 miles away.
Union Pacific has argued that the new branch will significantly enhance logistics efficiency, reduce highway congestion, and provide more sustainable transportation options for both inbound raw materials and outbound finished products.
Environmental Review Completed
The STB’s approval follows the completion of a comprehensive environmental review conducted by the agency’s Office of Environmental Analysis (OEA). In late February 2026, the OEA issued a Final Environmental Assessment (EA), concluding that the project would not result in significant environmental impacts provided that recommended mitigation measures are implemented…