Its construction has been a frequently muddy, often noisy and sometimes traffic-inducing process, but in about three weeks a key section of the Grand Parkway will open to motorists.

The tollway segments between U.S. 290 and Interstate 45, totaling 23.6 miles, are expected to open in the first week of February, said Quincy Allen, the Houston-area district engineer for the Texas Department of Transportation.

"We've been working at it," Allen said Tuesday, announcing the opening at a North Houston Association meeting attended by many of the engineers, elected officials and business leaders who have waited years for the project. Construction of the $1.1 billion, 38-mile stretch of the Grand Parkway from U.S. 290 to U.S. 59 near Humble started in July 2013.

Commuters and residents cheered the pending opening, saying it would relieve traffic congestion.

"Hallelujah," Karen Grabowski said when told the opening was imminent. "Seriously, I've been praying for this moment."

Grabowski, who lives near the Exxon Mobil campus in north Harris County, said she and her husband often visit relatives in San Antonio and shop close to U.S. 290. Avoiding suburban traffic along the Sam Houston Tollway will make the trip much more pleasant, she said.

TxDOT spokeswoman Raquelle Lewis said the remaining segment under construction - from I-45 to U.S. 59 - is on pace to open by the end of March. Work on that segment has been delayed by heavy rains last May, June and October.

In the meantime, Lewis said, crews will complete the lane striping and other finishing touches from U.S. 290 to I-45 and open all of the lanes and entrance ramps between the two freeways.

Eastbound traffic on the Grand Parkway will have access to northbound and southbound I-45 as well as the frontage roads in the area, Lewis said. Drivers on I-45 in both directions will have access to the westbound parkway. The full interchange with U.S. 290 will open when the lanes do, Lewis said.

Construction has not always been smooth. Residents along the parkway complained about noise, although analysis did not justify their desired sound walls. Construction-related traffic problems led some to ask state officials for relief. Critics say the parkway exacerbates Houston's suburban sprawl by encouraging greenfield development that benefits large landholders as opposed to most Houstonians.

The construction effort, meanwhile, has been enormous, according to figures provided by Zachry-Odebrecht Parkway Builders, the joint venture building the tollway. Crews installed 4,000 bridge beams and poured 1.8 million square yards of concrete - enough to build 11 NRG Stadiums.

When the segments open to I-45, 56.2 miles of the parkway will be open from U.S. 59 in Sugar Land to I-45 in Spring. The portion from I-45 to U.S. 59 near Humble will add another 14.8 miles.

When tolling on the new segments starts - which could happen when they open, or later if officials offer a grace period - the entire U.S. 59 to I-45 trip would cost $10.50, more than 18 cents per mile.

The opening, however, is hardly the end for the Grand Parkway. Allen said state officials are expected later this year to choose a builder for the next segments, from U.S. 59 near Humble to Interstate 10 east of Baytown.