The eight-hour closure is scheduled to begin at midnight Sunday and will remain in place until 8 a.m.
In preparation for the closure, multiple on- and off-ramps along the 60 Freeway, as well as connectors to and from the Orange (57) Freeway, will begin closing as early as 7 p.m. Saturday, according to the San Gabriel Valley Council of Governments.
Signed detour routes will be in place to guide motorists around the closure area. Drivers are strongly encouraged to plan ahead, use alternate routes, and allow for additional travel time.
As part of the 57/60 Confluence project, planners aim to relieve congestion, improve safety and support traffic flow. Improvements include redesigned ramps and interchanges, the addition of mainline and bypass lanes, and safer traffic flow to eliminate weaving.
The area constitutes a freeway interchange connecting Los Angeles, Orange and San Bernardino counties, carrying more than 350,000 vehicles daily through Diamond Bar and the city of Industry, planners said.
Due to heavy truck traffic, limited lanes, and dangerous merging patterns, it is considered the worst truck bottleneck in California and ranked the seventh-worst in the nation, according to the American Transportation Research Institute, and is among the highest truck accident locations in Southern California.
The temporary closure is necessary to support critical construction activities for the chokepoint relief project. The closure will help ensure motorist safety while crews demolish a section of the existing Grand Avenue Bridge, San Gabriel Valley officials said.
Members of the public can stay up to date on closure information and detour routes by visiting the project website at www.sgvcog.org/5760project or by following @5760Project on social media.