Plans to widen part of Farrington Highway in Nanakuli — touted as a way to reduce congestion on the Waianae Coast — have been delayed after crews ran into “unforeseen conditions with underground utility lines,” according to the state Department of Transportation.

The $10.1 million project to add a 10-foot-wide auxiliary lane on the four-lane highway between Nanakuli and Haleakala avenues for vehicles turning left was initially slated for completion in May after work began in 2014. The department said crews encountered problems when they found utility lines that were not part of the construction plans, which resulted in several months of delays, plan reassessments and a redesign by engineers, spokesman Tim Sakahara said in an email Tuesday.

Other project improvements include a new 8-foot-wide shared pedestrian and bicycle pathway, the relocation of utilities and upgrades to traffic signals, street lighting and drainage systems.

The Department of Transportation has received approval from the city Department of Planning and Permitting on updated design revisions, and daytime construction will continue behind the barriers this week. Work on the southbound lanes to install a sewer line resumed Tuesday from 9 p.m. to 4 a.m. with a contra-flow provided. Sakahara said officials are working with the contractor to try to move up the targeted April 2017 completion date. Electronic message boards have been placed to inform residents of lane closures, he said.

State Rep. Andria Tupola (R, Kalaeloa-Ko Olina-Maili) said there needs to be more done now to alleviate traffic, adding that the widening project would help. Tupola said the Department of Transportation is not doing a good job in communicating with residents about project schedules and lane closures, pointing to last weekend’s traffic gridlock when the department failed to inform motorists about maintenance work. (The widening project wasn’t the cause of the gridlock.)

“It (Nanakuli widening project) would help a little, but at the point we’re at, we need to look at all of the options,” Tupola said Tuesday. “I think people want to hear the update for sure about the timing, but what they really want to hear is what’s going to be done in the meantime.”

Several lawmakers and residents have pushed for more efforts to relieve traffic on Farrington Highway, including a secondary access route. Many have been critical of state and city agencies for the handling of construction schedules. Numerous accidents and construction work have resulted in west-side motorists spending hours trying to get to and from work. Some residents say they leave at 4 to 5 a.m. to drive to town for work, while bus riders contend that the one- to two-hour commute can be exhausting, especially when there are no seats available.

Richard Landford, chairman of the Nanakuli/Maili Neighborhood Board’s Transportation Committee, expressed similar frustrations as Tupola, describing the daily traffic he and other residents endure as “disgusting.” He said the widening project would be helpful, but questioned why plans do not also call for an additional right lane for buses.

“We’ve been asking for the left-turn lane for over 30 years. From what I understand, it’s always been asked for,” said Landford, a lifelong Maili resident. “We spend more time on … Farrington Highway than we have spent time with our families, with our kids, with our wives. It’s heartbreaking for us.”

For information on DOT lane closures, visit hidot.hawaii.gov/highways/roadwork/oahu.