Calling a planned high-speed rail connection to Dallas “an idea whose time has come,” Houston Mayor Sylvester Turner signed an agreement this week with the bullet train’s backers that both sides said is the first of many steps to making the trip a reality.

“This is the starting point to begin the process of definitive agreements,” Turner said, underscoring that the agreement between Houston and Texas Central Partners commits both to cooperate on a project each wants built.

The city and company will share environmental surveys, utility analysis and engineering related to the project and surrounding area.

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.

City officials have praised the project, with the mayor citing it among examples of his goal of reducing automobile dependency. Texas Central also touts huge job gains for the Houston area. Statewide, the company said the project will create 10,000 jobs annually for four years.

About 1,000 jobs will be permanent to operate and maintain the system.

The deal does not require City Council approval, though future agreements that commit the city to specific actions would.

“It shows the benefit of big ideas,” said Houston businessman Drayton McLane Jr., a member of the Texas Central Partners board of directors.

McLane compared the train to other major public and private projects in Houston’s past that steered the region to economic success, such as the dredging of the Houston Ship Channel and development of the Texas Medical Center.

“To think we have the largest economy in the world, and we have zero high-speed rail,” McLane said, rattling off advances in Russia and China.

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

A number of specifics of the project are also unresolved in the Houston area. Depending on the exact location of the train station, city officials expect it to radically increase current demand from travelers, requiring significant investment in widened roads and improved bus service.