Houston’s upcoming rail expansion is poised to be even bigger, as officials study possible changes that could have trains running nearly to the Heights and as close as practical to the city’s planned botanic garden.

Metropolitan Transit Authority officials are still tweaking the agency’s long-range plan, estimated to start with $7.5 billion in improvements aimed at developing 75 miles of bus rapid transit and at least 16 additional miles of light rail. And Metro is still studying substantial changes, ranging for streamlining parking options into a planned light rail extension to Hobby Airport and possibly adding another two miles of train tracks and extending service from downtown to near the Heights via Washington Avenue.

Metro officials are putting the final touches on bus and rail plans that residents will likely have one last chance next month to shape before the November ballot.

What people will see at the public meeting, however, is a work-in-progress.

“We are headed in the right direction based on all our community output,” Metro chairwoman Carrin Patman said, citing the reaction from elected officials, community groups and commenters at dozens of meetings around the area. “I think we are moving toward a wonderful plan to take out to the voters.”

Since reforming the broader plan in January, Metro has largely left the plan untouched, with the exception of plans for rail to Hobby that have seen numerous options weighed. Because of those changes and public input, officials Thursday said they are also studying possible rail service along Washington Avenue to Heights Boulevard.

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The long-range plan already includes a 0.2-mile extension of the Green and Purple Lines from their western end in the Theater District of downtown to the Houston Municipal Courthouse. The new proposal, suggested by officials with the Houston Downtown Management District, would continue that extension farther, likely by taking the line along Houston Avenue and then west on Washington Avenue. Additional stops would be at Sawyer and Studemont.

“I would be really curious what the ridership models will show,” said Metro board member Sanjay Ramabhadran.

Officials stressed the proposal is being evaluated and is not part of the plan yet.

“We’re looking at it,” Patman said.

With few specifics outlined, many residents of the nearby Sixth Ward, bordered by Buffalo Bayou and Washington Avenue, and the Heights cheered the possibility.

“I’d get rid of my car to ride it,” said Paul Miles, 32, who lives with his wife and daughter about three blocks from Washington and Sawyer.

In social media posts, multiple observers applauded the decision, adding that more rail along Washington, perhaps as far as Memorial Park, would be warranted. Many cited the dense residential and commercial development along Washington, making it an ideal corridor for major transit.

Voter support, and the plan’s promises, come with a caveat that many people will be approving things that are not certainties. Many of the specifics of where lines run will be worked out if voters allow Metro to borrow the money for the projects, using future sales tax revenues but not including any increase in taxes.

“Even if the referendum is passed, we will go through extensive community involvement,” Patman said. “(The referendum) won’t show streets granularly. The 2003 referendum didn’t and this one won’t either. … What we are trying to do is our best here.”

A looming criticism of the 2003 referendum by opponents has been the changes that occurred after voters narrowly approved it. A planned light rail line from the University of Houston and Texas Southern University area through Midtown and into Uptown languished under intense opposition that strengthened when the “Westpark Corridor” on the 2003 ballot morphed into a plan that ran rail along Richmond Avenue to Greenway Plaza.

The upcoming plan proposes bus rapid transit, potentially along a similar route or using dedicated or managed lanes along Interstate 69, rather than light rail between the university campuses and Uptown.

Though the University Line shifted to buses, rail dominates future transit discussions, even if Metro is proposing a historic level of bus rapid transit.

“A lot of oxygen is consumed by rail to Hobby (Airport),” Ramabhadran said.

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Getting a train to the airport that enjoys political support relies on tying the existing Green and Purple lines together somewhere near Loop 610 and Interstate 45.

“The broad-base community wants rail to the airports, to both airports, quite frankly,” Patman said, reiterating that rail to Bush Intercontinental Airport remains too costly for a first round of projects.

The Hobby line has dominated discussions of the plan since a draft proposal was unveiled last July.

Facing intense pressure from city officials in Third Ward and Houston’s East End, the initial plan was to run both the Green and Purple lines to Hobby. Citing the expense, Metro officials said it would be more practical to take only one line to the airport, but sought a compromise plan that would extend both lines to a common point, then have both proceed from there along a single route.

On the east side of the city, the specifics of exact routes is in flux, as officials seek to have the rail serve all the places they want but run through none of the communities they don’t want disturbed.

The preferences could lead to a curvy line. District I Councilman Robert Gallegos outlined the community’s desire for the Green Line extension to avoid heading south via 75th Street because of the risk it would require development along green space that’s part of Mason Park. At the same time, serving the planned Houston Botanic Garden near Broadway and Interstate 45 is a priority.

“For me the option is going down Broadway,” he said.

Gallegos, however, opposes taking the light rail along Broadway south of I-45, because of the community’s recent redesign of the esplanade, meaning the line would swing westward from the botanic garden to Telephone Road, where it would connect with the Purple Line.

The hope, Metro officials said, is to find a solution, or at least the best option — although further study could significantly complicate meeting everyone’s preferences.

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Broadly, officials said there are too many advantages not to run rail to the airport and through some of Houston’s more neglected neighborhoods within Loop 610. The service would be a valuable link between the airport and convention-goers headed to downtown hotels and even rooms around NRG Park, served by the Red Line.

As the southern-most rail station, the airport — or someplace near it — could also be critical to lure suburban commuters who might be willing to drive to Hobby, but complete their trips via rail much like the park-and-ride system does for suburban riders.

“Regardless of how we get to Hobby, I think it is paramount we put a park-and-ride lot at the end of it,” Metro board member Jim Robinson said.

He added that all lines, in some form, should offer parking at their ends to lure commuters.

Robinson, who works in the Harris County Administration Building in downtown Houston, used his own commute as an example. On work days, he travels south on I-45 into downtown. Once the Red Line connects to the North Shepherd Park and Ride lot — an extension included in the plans — he’ll have easier access to his office on Preston.

“I would ride the train every day now if I could get on at North Shepherd,” Robinson said.

Editor’s Note: A previous version of this story misstated the number of miles of bus rapid transit planned by Metro. Officials are proposing 75 miles of BRT.

dug.begley@chron.com