Two proposed commuter rail lines explain much about race, economic class and political clout in Los Angeles County.

One would tunnel under the Santa Monica Mountains, following the route of Intestate 405 through the Sepulveda Pass. It would connect two largely white and prosperous areas—the west San Fernando Valley and the Westside—to Los Angeles International Airport. It would connect with the planned Wilshire subway near UCLA. The second would run from Artesia to Union Station, serving the working class, mostly Latino population in the flatlands of southeast Los Angeles County.

The two proposed lines are part of a great number of projects that the Los Angeles County Metropolitan Transportation Authority (Metro) board approved June 23 to be financed with a countywide half cent sales tax increase on the November ballot. It needs approval by two thirds of the voters—a tough sell on a ballot that will be crowded with tax increase and bond proposals.

It would increase the sales tax in Los Angeles County to 9.5 percent—up to 10 percent in Santa Monica and some other cities. The measure comes on top of voter approval in 2008 of another transit sales tax increase, Proposition R.

But while that measure will eventually expire, there is no expiration date for the new plan. Backers of the measure say that the no-time-limit provision is necessary to pay for all the proposed projects. But Los Angeles County Supervisor Don Knabe protested that “This is a forever tax.”

In the months ahead, the tax and many of the projects throughout the county will hopefully be subjected to the intense debate they deserve. What first struck me about the Metro proposal were the economic, political and ethnic differences of future passengers on the Sepulveda Pass and Southeast Los Angeles county commuter lines.

The Southeast line would begin at Artesia and head northward through working class Bellflower, Bell, Huntington Park and then into similar areas in the city of Los Angeles, ending at Union Station. The working people who live there, mostly Latino, depend on public transit and high ridership is predicted. The route follows an existing but abandoned Red Car rail right of way and construction seems to offer few obstacles. But the Metro board, in assembling its list of projects, put completion date off to 2041, a substantial and inexplicable delay from the original plans.

“Imagine there are several Los Angeles County cities that make up one of the densest urban areas in the country, where much of the young, transit-dependent, ethnically mixed population commutes daily to jobs in other parts of the county. This would be one of the first areas to get a new rail line to the region wide transit hub at L.A. Union Station, right?” Huntington Park City Council member Karina Macias wrote in the Los Angeles Times last month.

Macias was wrong. Macias’ strong argument lost out to the politics of transit and the love of transportation engineers for really big projects.

The Sepulveda Pass has it all. The valley and the Westside are leaded with high voting residents, all of them needed for passage of the tax increase. Voter turnout in Southeast Los Angeles County is usually low.

And the Sepulveda Pass project is big enough to satisfy the most grandiose engineering ambitions, requiring a seven-mile tunnel under the Santa Monica Mountains offering engineers and construction people many challenging problems.

Then there’s another aspect of the politics. The difficulty of tunneling under the Sepulveda Pass would provide work and big contracts for the engineering and construction firms that wield considerable influence with some Metro board members. These firms would also provide much of the financing of the campaign to get the tax increase approved. Construction worker unions would also support the project as it would provide thousands of badly needed jobs.

The Southeast cities are trying to fight this, demanding an expansion of the Metro board to include more of their representatives. They say Metro officials have not given the Southeast line a high enough priority. But longtime Metro supporters former county Supervisor Zev Yaroslavsky and Richard Katz, who, as a state legislator helped create the Metro board, argued in a piece in the Los Angeles Times, that a bigger board would diminish the influence of the biggest city, Los Angeles. In addition, they fear, it could doom the tax increase proposal and threaten all the transit projects by alienating Los Angeles city voters.

Much is at stake. Metro expansion is changing Los Angeles. If you don’t think so, consider the proposed high-rise development near the Expo Line station at La Cienega and Jefferson boulevards. Without the Expo train, there would be no development. The small cities of southeast Los Angeles County want their share of such prospective riches, as well as the convenience and mobility offered by the commuter trains.