Road construction crews are scheduled to begin work this week on a new 2.8 mile lane designed primarily for slow-moving trucks climbing the Mount Sexton pass on northbound Interstate 5.
Work on the $28 million project north of Grants Pass is expected to continue into the summer of 2014. The northbound right shoulder of the freeway will be closed during construction, but traffic lanes generally will remain open.
The project also includes repaving more than 14 miles of Interstate 5 between Hugo and Glendale, including the southbound curves just south of the Smith Hill summit.
The Oregon Department of Transportation says most of the climbing lane work can be done without lane closures. Some temporary lane closures will be required, particularly where the existing road is narrow, such as the section near the Sexton Pass summit.
The project will require some short-term ramp closures for paving. ODOT will alert nearby businesses prior to these closures.
Most freeway climbs are built on grades of 5 percent or less. However, the northbound climb over Sexton Mountain reaches a maximum grade of 6.13 percent. On steep grades such as Sexton, trucks frequently slow to less than 30 miles per hour while passenger vehicles continue at 65 miles per hour or more.
ODOT said this difference in speed can be hazardous, particularly when one slow-moving truck attempts to pass another, thereby blocking both lanes for most of the climb up the hill. Some cars may be forced to brake hard or suddenly change lanes to avoid a collision.
Interstate 5 in Southern Oregon also has steep grades at Smith Hill and Stage Road Pass, but ODOT is scheduled to construct only one climbing lane at this point.