Transportation officials in Los Angeles, CA approved an $8.5 billion, 31-km (19.3-mile) light rail line project that will include 3.7 km (2.3 miles) of underground tunneling. The line will serve largely working-class Latino communities in southeast Los Angeles County, and the officials agreed to look for ways to speed up the project slated for completion in 2043.

The Los Angeles Times reported that the line runs from Artesia northwest to Union Station, cutting through the cities of Cerritos, Bellflower, Paramount, Downey, South Gate, Cudahy, Bell, Huntington Park and Vernon. It would provide key connections to other lines, helping build out a rail system decades in the making.

The costs of the project is $8.5 billion and is more than double the original estimate. The Metropolitan Transportation Authority decided to construct the project in two segments.

Local leaders have complained about the long wait for rail service.

The rail line was part of Los Angeles Mayor Eric Garcetti’s plan to build 28 transit projects by the 2028 Olympics.

The first 23.8-km (14.8-mile) phase runs from Artesia along a former Pacific Electric right of way to Slauson Avenue and Long Beach Boulevard, where it would connect with the A (formerly Blue) line. Groundbreaking for the $4.9-billion phase is slated for next year and completion about 10 years later.

The second phase heads north 7.2 km (4.5 miles) from the Slauson depot to Union Station and is set to be completed by 2043. About half of the line is planned to run underground through Little Tokyo, where Metro construction disrupted businesses for years and tunneling is driving up costs.

The Metro board unanimously approved a plan that will look at cheaper alternatives to tunneling that could accelerate construction for the second phase. In an hours-long public comment period, dozens of elected officials representing the communities along the rail line pleaded with the board to speed up the timeline.

The rail line was a cornerstone of Measure M, a $120-billion half-cent sales tax approved by voters in 2016, which gained widespread support among elected officials in the region. Along with Measure R, approved in 2008, the tax fueled a rail construction boom.

Metro plans to tap $3.1 billion in federal funds and an additional $850 million in state funds for the first leg of the rail line.