New Orleans transit advocates have long pushed the Regional Transit Authority to provide better shelter and amenities at bus and streetcar stops as a way to ease the waits for riders and encourage more people to use the system.

It’s a goal that’s in line with the RTA’s own vision as it pushes forward with plans for a major new transit hub in or near the Central Business District that would serve numerous bus lines converging on a single location.

Advocates such as the group Ride New Orleans have welcomed that idea, but now they have a possibly surprising message for the agency: Take it slow and get it right the first time.

The push for a CBD hub comes as the RTA is also embarking on another priority of transit advocates: the commissioning of a master plan that would guide the agency’s development for the next two decades and provide a blueprint for a transit system that better serves its riders.

That plan likely won’t be ready until next year, and some argue the agency should hold off on a major investment like a new hub until it’s complete.

“It doesn’t make sense to us to invest in a fixed capital asset like a transit hub without knowing what the master plan looks like,” said Jacquelyn Dadakis, president of Ride New Orleans’ board of directors. “If we don’t know for sure long term that’s where our buses are going to go, we’re locking ourselves into something that’s a very expensive investment.”

That caution comes as transit groups like Ride New Orleans and local officials are talking with renewed interest about a more regional transit system and better service to underserved neighborhoods. At the same time, the RTA and Transdev, the company that manages its operations, have announced plans for a new ferry terminal and other improvements, such as extended service and overnight hours for numerous routes that are expected to go into effect in March.

Combined, those service improvements are expected to add about 20 percent more RTA trips on weekends; they represent part of a $10 million increase in services over the past two years.

RTA General Manager Justin Augustine said the history of New Orleans suggests there’s little reason to think the CBD won’t remain crucial to the city’s economic future. In that case, there’s little reason to worry that a downtown hub won’t serve the needs of future riders or fit in with the master plan.

“I don’t see downtown New Orleans changing in 20 years,” Augustine said.

He said the aim is to create a comprehensive and multimodal transit system that would ease riders through a network largely based in the downtown area.

“We’re really trying to plan a transit system that fulfills the needs of the riding community,” Augustine said.

Planners are looking at four possible sites for a downtown hub, with the potential for smaller hubs that would feed into the main transit facility and provide more direct service to destinations such as the new University Medical Center and the under-construction Veterans Affairs hospital next to it.

There have been no estimates of how much the project could cost; that will depend in large part on the site and the amenities that are eventually offered.

Officials had initially suggested a hub could be up and running by 2018, coinciding with the city’s tricentennial. But current plans could push the completion date into the early 2020s. A study by consultants on the various proposed sites is now expected at the end of April, after officials delayed the process to broaden the scope of the sites being considered.

Once a site is selected, the RTA plans to apply for federal money to help build the new transit center, which will kick off a lengthy process — at least five years to get through federal approvals, design and construction.

The new ferry terminal is on track for 2018, Augustine said. That site is unsuitable for a transit hub because of the difficulties of getting so many buses up and down Canal Street, he said. The terminal project, expected to cost between $15 million and $20 million, has received a $10 million grant from the federal government, and additional money is available to buy two new boats, Augustine said.

Those projects are being folded into the city’s own long-term planning process, said Cedric Grant, Mayor Mitch Landrieu’s chief infrastructure adviser. “You should be able to enter the (transit) system at any point and transfer seamlessly,” he said.

Ride New Orleans, however, sees a lot more potential for significant shifts in the city’s transit service. While the CBD and adjacent neighborhoods likely will always be important destinations for the system, at least some of the riders boarding buses in that area now do so simply because that’s where routes terminate and transfers take place.

If the RTA were to invest in more crosstown routes that aren’t centered on Canal Street, or increase its focus on regional efforts that would better integrate service to Jefferson Parish or the River Parishes, some of the sites now being considered for the new hub may no longer be ideal, Dadakis said.

“If these bus routes start going across town and potentially across parishes, we probably won’t see the large crowds we see today (at CBD bus stops). I wouldn’t want to see us building for what we have today versus what we could have,” Dadakis said.

Follow Jeff Adelson on Twitter, @jadelson.