For many long-suffering Houston drivers, a solution to the infuriating bottleneck on Interstate 45 through downtown is likely something they thought they wouldn't live to see.

More than a decade ago, a plan pitched to solve the problem - moving the interstate to the east side of downtown and demolishing the Pierce Elevated - appeared so preposterous they thought it would never get off the ground. It was too big of a change, too ambitious, too expensive and too disruptive.

Turns out it was also too good to pass up, leading to efforts by local transportation officials to now include the first phases of the project in an updated, expanded statewide transportation plan. So the project some only dreamed about is, at least on paper, a reality, pending the allocation of more than $900 million for the reconstruction of two major interstate intersections in the downtown area.

Houston area leaders: Time to push transportation improvements beyond adding and widening freeways

Though these first steps are incremental compared to the overall plan, officials say they are important and send the clear message: The I-45 freeway is relocating and the elevated portion along Pierce will be abandoned and maybe demolished within the next dozen years.

"We are turning the key and starting the engine and moving," said Quincy Allen, district director for the Texas Department of Transportation in Houston.

Work on revamping the freeway intersections is slated for late 2020 or early 2021, years ahead of when state officials first predicted when they unveiled their construction plans in 2014.

For the Houston region, it might be the most significant freeway project in anyone's lifetime. That's because it reconfigures the three interstates that form the backbone of how Houstonians move - I-45, I-69 and Interstate 10 - in the one area where they are so closely tangled and reliant on drivers making transitions from one to another as smooth as possible.

Even with the environmental clearance pending, the money is there for when construction is ready to begin on the first of the five-part overall project state transportation officials have called "transformative" to handling Houston's traffic needs for the next 40 years.

The state officials - flush with two rounds of voter-approved money that gives them $5 billion to spend on congestion relief in the five largest Texas metro areas - are set next month to approve another round of funding, this time including two projects that actually are the first phases of the massive $6 billion-plus widening and redesign of Interstate 45 northward from downtown Houston.

The state commitment, provided the Texas Transportation Commission proceeds with its planned changes to the Unified Transportation Plan that sets all state highway project priorities, would contribute $923 million of the $1.7 billion needed to rebuild I-45, I-69 and Texas 288 where the three freeways converge. Most of the money comes from Texas Clear Lanes, a program aimed at addressing congestion in the state's five biggest cities.

"This is the heartbeat of the intent of Texas Clear Lanes," said Raquelle Lewis, spokeswoman for TxDOT in Houston.

The major highway configuration changes will have many benefits for drivers.

"It enables to start affecting, in a positive way, the movements and lane assignments, those sorts of things, to cut down on the (traffic) weaving," Allen said.

Green space not yet part of massive highway plan

The first part of the project, along I-69 near Spur 527, aims to lessen the congestion caused where traffic from the Greenway Plaza area flows into a bottleneck where I-69 drops to three lanes, with two others for the spur. It would add another lane, and widen the already depressed freeway through Montrose and Midtown.

The project's next part takes that even further, burying the portion of I-69 that now is elevated east of Spur 527. Local streets that now flow beneath the freeway will stay where they are, but cross atop it.

"I expect us to continue to progress and go in a counter-clockwise motion around downtown," Allen said.

Based on projections, when the entire downtown ring is completed and I-45 is in place parallel to I-69, the amount of congestion drivers endure will be cut in half, based on 2040 traffic estimates.

Thousands of drivers are all-too-familiar with the delays at Spur 527 and the gargantuan gridlock where I-45 and I-69 cross.

"Anytime of day, it's backed up," said Susan Brighton, 60, who commutes daily between Upper Kirby and downtown.

Brighton, who said she's kept up with the proposed I-45 changes but with a skeptical eye, said she was "shocked" to think after years of talk it could start in a little more than three years.

"I guess be careful what you wish for," Brighton said.

The first phases of work are designed to allow for I-45 in the central business district to stay where it is now, but also accommodate where it eventually will move.

Work is scheduled to begin later this year to reconfigure how traffic northbound on I-45 connects to I-69 northbound and southbound. That project will build one ramp that will have to be adjusted later once I-45 changes, Allen said.

The plans for the upcoming highway work also do not address a number of possibilities that have been raised to develop open space or parks atop the buried freeways.

Klyde Warren Park in Dallas atop Spur 366 is hailed as a model of what Houston could do, especially east of the George R. Brown Convention Center.

Some also have suggested retaining part of the Pierce Elevated for a linear park or overlook of some sort.

Those discussions are separate and apart from any redesign of the Houston freeway system, nor are they funded by any of the committed state transportation money for the state's largest cities.

"We think a lot of the deck parks, but we're going to need partners for that," Allen said.

Texas voters had their say on road work

The Texas traffic congestion money is derived from Proposition 1, which voters approved in 2014, and Proposition 7 they approved the following year. With at least $3 billion annually in additional highway spending, and possibly up to $5 billion annually in future years, the Texas Transportation Commission added $28.9 billion to the state's 10-year transportation plan and began doling it out to specific projects last year.

"We are responding to how our Texas voters and Texas people are using their transportation," said transportation commissioner Bruce Bugg.

The voter-approved funds only can be used on TxDOT highway projects, not for public transit or toll roads.

State officials now have turned their attention to the highway projects spurred by elected leaders in Houston, Dallas, Fort Worth, Austin and San Antonio who are rapidly moving them forward to capture the money.

A third Houston-area project unaffiliated with the massive I-45 redesign also benefits from the new state transportation money. Officials plan to spend $98.3 million to rebuild portions of Loop 610's southern segment, including adding a new overpass at Cambridge that will span that street, as well as Almeda and the nearby Union Pacific Railroad tracks. TxDOT plans to use $75 million of the money targeted to ease traffic congestion in the state's metro areas for the project.

"Don't overlook that," Allen said. "That's a big project for us."

It doesn't, however, come close to the magnitude of the I-45 redesign through downtown, which on paper is among the most expensive highway jobs TxDOT ever has proposed. For perspective, the price tag of that interstate revamp dwarfs the $1 billion widening of I-45 south from Houston to Galveston, being built now in stages. Even the $1.8 billion, ongoing 38-mile widening of U.S. 290 from Loop 610 to Waller is but a fraction of the I-45 project.

Eventually, the proposal is to widen I-45 from downtown to the Sam Houston Tollway in Greenspoint. Combined with the downtown efforts, it is estimated to cost at or near $7 billion.

Reopening the tolling debate

The much-later parts of the ambitious freeway project reignites some the frustration related to TxDOT's reliance on toll roads.

North of downtown, plans for I-45 call for managed lanes - two lanes in each direction - open only to high-occupancy users and toll-paying solo drivers similar to the lanes today on I-10.

Those lanes will integrate with the free lanes planned downtown, though toll lanes will not extend throughout the downtown area, just feed into it.

Though area drivers have cheered some tollway efforts - notably the Grand Parkway in Houston - other such projects statewide have checkered pasts. For example, state highway 130, south of Austin, was built with a concession agreement but eventually the builders defaulted on their debt, leaving creditors and the state to sort out how to keep the road open.

At one time, toll roads in Texas were just as pleasing as the recent bounty of voter-approved state highway improvement spending, state transportation commissioner Victor Vandergriff recalled.

"All my friends who were proponents of that have gone away," he said.

Frustration over tolling remains, said Don Dixon, a frequent toll road critic from San Antonio.

"The public was asleep at the wheel in the 2001-03 period," Dixon said, referring to when many road projects were approved with money raised by borrowing and then supposed to be repaid using toll revenues.

Dixon, and others, have said they do not want to see Texas invest in highway projects that accelerate more toll roads, saying some of the upcoming I-45 project blurs the line by prepping toll projects.

"To me this is continuing forever the toll policy that… the public wants to back away from," Dixon said.