FRESNO, Calif. (KFSN) -- The California High-Speed Rail is starting its first underground project to accommodate trains passing through Downtown Fresno. Construction will eventually impact traffic on Highway 180 in the coming months.Heavy machinery is in place for a project that will give the downtown area a major facelift. A two-mile long Fresno trench must be dug to fit through a Highway 180 passageway. The High-Speed Rail route will begin to dip near Roeding Park along the union pacific tracks."Between Olive and Belmont that's where we start getting depressed. We go underneath this whole area and we come back a little bit north of Stanislaus," said Hugo Mejia, Design and Construction manager.Mejia said it will take between 18 to 24 months to dig the trench under 180, the Dry Creek Canal, as well as a Union Pacific Spur track."The trench is 45 feet deep or so going underneath these facilities you see here."Caltrans crews are also in the midst of moving a two and a half mile stretch of Highway 99 near Clinton about 100 feet to the west. But the LA Times reports the project is behind schedule and over budget-- needing an additional $35 million more from the state.The High-Speed Rail Authority admits it moved the completion date from June 2018 to December but adds, "This does not impact the overall construction schedule or budget for the first construction segment in the Central Valley."These columns along Highway 99 near North Avenue will be part of the downtown viaduct structure, which will signal the south entrance into the Fresno High-Speed Rail Station."We do see these sporadic different sites within the Valley. They're really going to start coming together as we progress and add more construction sites," said Toni Tinoco, HSR.The High-Speed Rail Authority hopes to have its first train running in 2025.The Fresno trench project will impact traffic as it will require lane shifts on Highway 180 with a westbound lane shifted to the eastbound side. That's expected to take place in about two months.