Motorists should expect delays and detours this weekend at Union Boulevard and Austin Bluffs Parkway, as crews scramble to finish the new interchange at the intersection.Beginning at 8 p.m. today, northbound and southbound Union Boulevard will be reduced to one lane, with no left turns allowed onto or from Union.That configuration will change at 8 p.m. Saturday, when both northbound and southbound Union will be closed at the intersection to accommodate work in the roadway.  Northbound Union traffic will be detoured eastbound on Austin Bluffs Parkway to Academy Boulevard. Southbound Union traffic will be detoured westbound on Austin Bluffs Parkway to Nevada Avenue.Union will be reopened by 6 a.m. Monday.Also on Saturday, from 7 a.m. to 5 p.m., the left lane of both east and westbound Austin Bluffs will be closed east of Union to allow old asphalt to be removed.Then, on Sunday between 7 a.m. and 7 p.m.. there will various lane closures on both east and westbound Austin Bluffs on the bridge to allow work on the bridge deck.Crews are pushing to finish the almost two-year project by November.