Caltrans is conducting groundbreaking ceremonies Tuesday for the widening of Highway 99 to six lanes from the 120 Bypass to Arch Road.

The ceremonies start Tuesday at 11 a.m. at the Delta College Manteca Center on Brunswick Road northwest of the Lathrop Road and Highway 99 interchange.

The initial phase will involve adding a lane in each direction in the median. That work starts this summer. Caltrans split the project into phases to take advantage of the fact the actual widening to six lanes did not require a time-consuming right-of-way acquisition process.

The $250 million project is part of an overall $496 million endeavor to widen the freeway to six lanes between Highway 4 (the Cross-town Freeway) in Stockton and the 120 Bypass.

The second phase of the project is the new Lathrop Road interchange. That means the flyover onramp will be removed and the existing Lathrop Road interchange replaced.

The new Lathrop Road interchange will include a bridge deck with four lanes, eight-foot-wide shoulders that can easily accommodate bicycles, and sidewalks. The off and on ramps will be on the north side of Lathrop Road with the ramps on the west side being aligned to tie directly with North Main Street that would be widened to four lanes to Northgate Drive.

The interchange will:

• realign the West Frontage Road through Delta College’s property in the northwest corner of the interchange and align it with Crestwood Avenue. Delta College is proposing developing 350,000 square feet of retail on the land.

• extend North Main as four lanes from Northgate Drive to tie into an intersection with the southbound on and off ramps at Lathrop Road. The road, designed to allow traffic to travel at 35 mph, would wipe out several older homes used for commercials purposes, the warehouse portion of Center Appliance and the small business complex built a few years ago between the existing curve and the overpass.

• provide a direct route for trucks accessing business and industrial parks that exist and are proposed between Lathrop and Manteca along the Airport Way corridor. It would also provide a direct truck route between Interstate 5 and Highway 99 in addition to the Highway 120 Bypass and French Camp Road.

• eliminate the modular home and trailer sales businesses on the southeast corner to accommodate northbound off and on ramps.

• relocate the East Frontage Road further east and extend it south of Lathrop Road behind developed parcels before curving back to the existing Frontage Road to provide access to Southland Road.

The on and off ramps at Little John Creek near Stockton Metro Airport will be closed with the frontage roads converted into cul-de-sacs.

The French Camp Road replacement interchange construction will follow the road widening.

The fourth and final stage involves replacement and mitigation planting.

The state is picking up $282.4 million of the tab for the overall Highway 99 upgrade through Stockton and Manteca from Proposition 1B bond proceeds. Measure K – the countywide half cent sales tax – is covering the rest of the cost. If it weren’t for the Measure K sales tax San Joaquin County in all likelihood would not have secured the state bond money.