Commuters who regularly use FM 646 near I-45 face spending months taking detours in 2019 as the Texas Department of Transportation begins a major intersection reconfiguration.As part of several projects to widen I-45 from six to eight lanes all the way to Galveston, TxDOT in March will begin flipping how FM 646 intersects with I-45. FM 646 currently passes over I-45, but by the end of the year I-45 will pass over FM 646, TxDOT Public Information Officer Danny Perez said.During the first phase of the project crews will close FM 646 to east- and westbound traffic and demolish the overpass, he said.“This will allow the contractor to construct the middle span of the new I-45 ... overpass at FM 646,” Perez said in an email to Community Impact Newspaper. “I-45 traffic will be disrupted periodically for main lane traffic shifts; however, on a day-to-day basis, the I-45 main lanes will maintain [their] current serviceability and capacity.”While FM 646 is closed, eastbound motorists will have to travel south along the I-45 frontage road to FM 517 and make a U-turn before continuing on FM 646. Westbound motorists will have to travel north to Hwy. 96 and make a U-turn, Perez said.Crews will also reconstruct the intersection and nearby frontage roads during Phase 1, according to TxDOT documents.The second phase will begin with the reopening of FM 646 to east- and westbound traffic. The contractor has about a six-month window from the demolition of the FM 646 overpass to reopen the road, with incentives for early completion, Perez said.Crews will also construct access roads and the southbound main lanes of the I-45 overpass during Phase 2, according to the documents.Perez said reconfiguring the FM 646 and I-45 intersection makes travel safer during emergencies.“The I-45 corridor is a hurricane evacuation route,” Perez said in the email. “In order to ensure that high-profile vehicles, emergency vehicles, rescue vehicles and emergency supplies are able to pass through the corridor without obstruction, overpasses over I-45 are being eliminated, and I-45 is being reconfigured to pass over these intersections.”Reconfiguring FM 646 and I-45 has other advantages, including the addition of bidirectional access roads and U-turn lanes, both of which will improve access to surrounding businesses and homes and reduce congestion. Crews will also install new sidewalks and traffic signals, Perez said.TxDOT has completed work at several locations along I-45 from the NASA Bypass to FM 517, which contains two I-45 widening projects.The first project is between FM 518 and FM 517, which began in November 2016 and is expected to finish in summer 2021. Its estimated cost is $121 million, Perez said.The second project is between the NASA Bypass and FM 518. It began in May 2017 and is expected to complete in late 2021 and will cost an estimated $99.8 million, Perez said.TxDOT plans to begin widening I-45 south of FM 517 toward Galveston, a $230 million project, starting in February, Perez said.