Citing complications from cities and railroads, the Metro Gold Line Foothill Construction Authority board approved a new work schedule for the 12.3-mile extension from Azusa to Montclair, pushing back the completion date at least two more years.

Instead of expecting construction to finish in 2023, the board last week set completion by December 2025 or early 2026, placing the opening of the light-rail extension more than nine years in the future.

“That is the reality of what we are faced with,” said Doug Tessitor, chairman of the independent rail line board. “If we can do it sooner than 2026 we certainly will.”

The authority’s CEO, Habib Balian, said the project will have to wait longer for funds to become available, so major construction will start in 2019, rather than 2017.

Metro’s Measure M, passed by voters in November, will funnel about $1 billion to the authority for the project, the second foothill extension. The authority finished construction on the original L.A. to Pasadena line from east Pasadena to Citrus College/Azusa Pacific University on the border of Azusa and Glendora on Sept. 23, 2015. After months of testing, the line opened on March 5, 2016.

In addition to being slowed by the availability of funds, more complications arose with construction, as details emerged last fall.

Some cities have objected to closure of two nearby intersections simultaneously to allow for alignment and laying of track. As a compromise, the authority agreed to stagger the work in consecutive chunks, adding almost two years of construction time, Tessitor said.

“It’s so you don’t tie up two consecutive intersections that disrupts traffic in a city,” Balian said. “All that just delays your schedule.”

One of the biggest slowdowns will come from existing freight railroads, such as BNSF, and Metrolink. Because the lines are located within the right-of-way between Glendora and Montclair, the tracks must be moved in a way allowing trains to continue running. Only after that can the light-rail tracks be laid and six new Gold Line stations built, Balian said.

“This is really two construction projects in one. It is a huge factor in all of this construction,” Balian said.

Metro’s schedule of Measure M projects lists a 2025 opening date, which will have to be adjusted forward.

Also, by lengthening construction time, costs rise due to higher payroll costs, new prevailing wages and general inflation, Balian said.

The Glendora-to-Montclair project cost will increase by about $118 million for a total cost of $1.37 billion, he said. Of that, about $70 million will be charged to San Bernardino County for the Claremont to Montclair leg; this would be the first Metro line to reach across the county line, and Measure M funds are for L.A. County only.

Having a detailed construction schedule will bring in tighter, more competitive bids, Balian said. It also may limit change orders. “We will have communicated what we want. They will understand the project and know exactly what they are getting into,” he said.

The construction authority hopes to bid for preconstruction work, namely the relocation of utilities, by summer and break ground in fall, Balian said. If a path is cleared on schedule, the major, $600-million design-build bid could be unsealed by late 2018 with heavy construction underway in 2019, he said.