Photo courtesy of New Mexico Department of Transportation
Workers with the New Mexico Department of Transportation successfully backfilled both washed-out approaches to the Greenwood Canyon bridge on U.S. 180.
The Best Project Program Award recognizes projects that are developed and constructed by NMDOT District personnel. The planning and coordination during a project are examples of the skills and knowledge that the men and women of the department provide every day to all constituents. The magnitude, complexity, coordination and teamwork are significant to this recognition.
District One won the 2023 Statewide Best Project Award for the Emergency Abutment Embankment & Approach Repair for Structure 6685 (U.S. 180 over Greenwood Canyon). This emergency project was required due to major flooding that occurred on Aug. 22, 2022 and Aug. 23, 2022, in the 13 sq. mi. drainage basin upstream of structure 6685, which overtopped U.S. 180 and caused both abutment embankments at the bridge to fail. The August 2022 flood event in this area was unusual in magnitude and overwhelmed the waterway opening at structure 6685 for the first time since it was put into service in 1966. U.S. 180 was closed unexpectedly for four days, stopping all travel between Cliff and Silver City, including emergency services and school buses.
The intent of the Emergency Abutment Embankment and Approach Repair was to provide expedited temporary erosion control measures. However, it will likely serve as a permanent fix because it was so well built and drainage analysis has confirmed that the waterway opening is adequate for future use per the current criteria. The total cost of repairs was $522,406.02.
The District One Heavy Maintenance Crew worked to implement this unique erosion control plan in a very efficient and effective manner and was able to complete utilizing their proper equipment, manpower and knowledge. They were able to complete the task, maintain public safety and get the structure open to traffic with only minimal delays. This was a complex project due to the size of rock and tight spaces for placement between the piers and abutments. This project required significant planning and coordination with District Maintenance Bureau crews, suppliers and contractors. The temporary erosion control portion of the project was performed solely by NMDOT forces using guidance from the District One Bridge Section, Department equipment, rock from a local supplier (T.G. McCauley) and traffic control plan per State Maintenance Standards.
Cliff Crew 41-44 and Heavy Maintenance Crew 41-88, along with the General Office Drainage Section, General Office Bridge Management Section, Chip Seal Crew (Crew 4181) and the District One Bridge Section all reacted well to this critical finding and safely expedited the use of U.S. 180 at this location as efficiently and effectively as possible.
Background
The Cliff Patrol recommended the of closing the highway for safety on Aug. 22, 2022, prior to failure of the roadway. The east approach slab became completely undermined and failed on Aug. 23, 2022, which left a hole in the roadway measuring approximately 10-ft. long by the entire width of the highway.
During the four-day closure of U.S. 180, Freeport McMoRan allowed emergency travel on a mining roadway three times a day to deliver supplies of food, medicine as well as emergency services while U.S. 180 repairs went underway.
Structure 6685 is located on a portion of U.S. 180 that serves 1,356 vehicles per day with 17 percent truck traffic as a rural minor arterial route. However, the detour around structure 6685 on paved highways is approximately 175 mi. U.S. 180 serves as an important route for U.S. Forest Service, NM State Parks, ranchers, citizens of numerous communities and other public commuters.
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