Backers of a Texas high-speed rail line on Thursday announced for the second time this week what they called significant progress on the controversial line, inking an agreement with Houston officials, detailing the work to come.

At City Hall, Houston and Texas Central Partners announced the signing of an memorandum of understanding, which commits both sides to share environmental surveys, utility analysis and engineering related to the project and surrounding area and work together to develop new transit and other travel options to and from the likely terminus of the bullet train line.

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In the memorandum, Texas Central notes the likely end of their Houston-to-Dallas line will be south of U.S. 290, west of Loop 610 and north of Interstate 10. The exact site has been long suspected as the current location of Northwest Mall.

The train will run on its own tracks, separated from roads and elevated in most places in the Houston area. Construction is expected to start late next year or early 2019, company officials said, and take between four and five years. The cost is expected to be at least $12 billion.

The cooperation between Houston and Texas Central is no surprise. City officials, notably Mayor Sylvester Turner, have praised the project, with the mayor citing it among examples of his goal of reducing automobile dependency.

“We also look forward to the project’s creation of job opportunities and economic development,” Turner said in a prepared statement.

The company and others have also touted the line’s private financing. Texas Central has said it will not fund the project with public grants, but might seek government-backed loans available to most private companies.

“This demonstrates how the free market can play an integral part in addressing America’s enormous infrastructure opportunities,” said Houston businessman Drayton McLane Jr., a member of the Texas Central board of directors. “The agreement continues the project’s momentum and shows the nation — and the rest of the world — how Texas does big things the right way for the public good.”

Despite enjoying robust support in Houston and Dallas – where Texas Central also has a memorandum with the city – the bullet train project has many detractors in rural areas of the state it will cross. Many skeptics, including some in the Legislature, have said they doubt the company’s chances and do not want Texans placed in the position of bailing the company out financially.

Many have also said the private company should not, and in some cases does not, have a right to use eminent domain to acquire land.