There's a lot of ground to cover before bullet trains carry riders between Houston and Dallas, but federal officials are poised to announce Wednesday that Texas and the private company planning the line have the go-ahead to begin environmental reviews.

Though a preliminary step, the notice to proceed expected to appear in the federal register Wednesday sets up a lengthy analysis on where a high-speed rail line would go between the two metro areas and what effect it would have on East Texas residents, plants and animals.

Often discussed, this moves a Texas high-speed rail project closer - albeit incrementally - to reality.

"It is now more than just talk," said Maureen Crocker, executive director of the Gulf Coast Rail District, which is supportive of passenger rail projects in the Houston area. "When they do this, it'll give everyone a much clearer idea of what this is going to be, and lay out the plan that so far has been private."

Robert Eckels, president of Texas Central Railway, the company proposing the line, said in a statement that the notice begins a process, "which, true to our overall philosophy, will be funded with private dollars."

The company has not released estimates of the line's cost, though speculation has put it at more than $10 billion. The cost could climb from there based on how many tunnels or overpasses will be needed - and how much land will need to be purchased - to connect the metro areas.

Company officials have said previously they are hoping to follow established routes, possibly acquiring land next to freeways and freight rail tracks, to stitch together a feasible path.

90-minute trip in 2021

If trains begin operating in 2021, as officials have said is the most optimistic schedule, the trip between the two regions would take about 90 minutes.

Regional transportation planners, state officials and train supporters have said for 20 years that traffic between Houston and Dallas - two of the fastest-growing metropolitan areas in the country - will necessitate options beyond Interstate 45 and commercial airline flights. Adding high-speed rail has long been considered the next step, simplifying business travel and potentially reinvigorating areas around the two downtown stations.

Before those trips start, however, years of work remains to design and build the project. Initiation of the environmental process doesn't lock public or private officials into anything, or set specific deadlines.

"Timelines for these kinds of projects vary widely," said Mike England, spokesman for the Federal Railroad Administration.

Public agencies, notably the railroad administration and Texas Department of Transportation, must conduct the review - including soliciting public comment and holding meetings in areas affected by the plan.

Crocker said the local rail district currently has a study examining how to bring passenger trains into downtown Houston.

"We've kind of kept the high-speed rail line in mind when we're doing that," Crocker said.

TxDOT officials did not respond to requests for comment.

90-day comment

The announcement kicks off a 90-day comment period before federal and state officials allow the environmental process to start. Engineering and studies will be prepared by an outside company paid by Texas Central.

Amassing the noise, groundwater, air and wildlife studies could take months, if not years. Though Texas Central has said it intends to fund the line without public assistance, it must follow the same standards as a highway or public rail project. Environmental risks must be studied, and significant damage caused by the line would need to be remedied, or the project would need to change to minimize the impact.

Typically initial studies are submitted to state and federal officials; then bureaucrats have a list of items they want to see changed or answered before the project even gets a public review.

"We look at every small bit of it," England said. "They are going to send it and we'll send it back."

If the project doesn't elicit significant public concerns - unlikely for a 240-mile project that crosses urban, suburban and rural terrain between two of the largest metro areas in the U.S. - the reviews could be completed quickly once officials and Texas Central agree.

The private backers of the line have said the 2021 opening is based on starting construction in 2016.