Westbound travelers on a stretch of Interstate 10 will see changes this week as part of an $86 million project to widen the interstate from the I-10/12 split to Siegen Lane, officials said Monday.

The changes mean that:

• Traffic lanes on I-10 westbound between Bluebonnet Boulevard and the split will move toward the median lane, with Friday being the tentative start date. That switch will exist for one year.

The median lane and what is now the westbound left lane will be in operation while new lanes are built on the 2-mile stretch.

• The westbound entrance ramp to I-10 at Picardy Avenue will be closed for one year while the lane shift is in place.

• The entrance ramp to westbound I-10 at Bluebonnet Boulevard will be closed from 8 p.m. Thursday until 6 a.m. Monday.

The work is part of a project that will add one lane in each direction from the split to Siegen Lane.

The project began in January 2009 and was originally scheduled to be finished by the end of this year.

But officials of the state Department of Transportation and Development announced in May that the work is 10 months behind schedule and is now set to be completed in fall 2012.

Moving westbound traffic toward the median of I-10 is set to take place from Friday to Sunday, weather permitting, according to Jodi Conachen, director of communications for DOTD.

Conachen said the new lane meets interstate standards.

DOTD officials said that, once the entrance ramp at Bluebonnet is reopened on Monday, motorists traveling west on Picardy should continue to Bluebonnet and use the I-10 entrance ramp there.

What is now the right lane for westbound I-10 travelers will be closed between Bluebonnet and the I-10/12 split when the median lane is opened.

The 10-month delay in finishing the widening work has triggered a dispute between state officials and the contractor, Austin Bridge & Road Inc.

The firm is based in the Dallas suburb of Irving, but it has an office in Baton Rouge.

An official of the company said earlier that frequent change orders from the state slowed progress on the I-10 expansion.

The additional lane in each direction covers a 4.1-mile stretch from the split to Siegen Lane.

It is one of several segments that will widen I-10 from the split to Highland Road and on I-12 from O’Neal Lane to Walker.

The work will cost at least $332 million.