A series of accidents — including two fatal crashes — choked South County freeways Friday reducing Interstate 5 northbound traffic through Lathrop near the junction with the 120 Bypass to a crawl for most of the day.
The biggest contributor to the snarl was a fatal accident that occurred when a vehicle went flying off the transition ramp from the westbound120 Bypass to northbound Interstate 5 after 10 a.m. The severely damaged guard rails forced Caltrans to make emergency repairs that took hours to complete.
The traffic backup at one point extended south nearly 10 miles almost to the Highway 132 interchange. Interstate 205 backed up beyond MacArthur Drive in Tracy while Eleventh Street was backed up to the roundabout at Grant Line Road east of Tracy.
The traffic snarl prompted some to head down Kasson Road to cross the San Joaquin River and head back up Airport Way to reach the 120 Bypass and Manteca or take county roads east to Ripon to reach Highway 99. Trucks and cars at one point were backed up for 2½ miles in stop and go traffic on Kasson Road.
Traffic was still barely moving when the afternoon commute from the Bay Area started. At the peak of the commute at 5 p.m. a crash near the Hammett Road interchange on southbound Highway 99 south of the Stanislaus River backed traffic up toward Manteca.
The Friday mess started shortly after 9 a.m. with a fatal four-car crash on Lathrop surface streets. The crash took place at Harlan Road and Louise Avenue east of I-5.
A witness said an eastbound Dodge 2500 pickup truck ran the red light and crashed broadside into a northbound Toyota Corolla spinning it around and causing damage to two vehicles waiting for the westbound Louise Avenue red light to change. 
The woman driver of the Toyota was trapped in her car and died at the scene.
One of the other cars was a Ford Focus with its driver receiving moderate injuries. The driver was transported to a Tracy hospital for treatment.  The other vehicle sitting at the light was a Sebring convertible but its driver was not visibly injured in the crash.
A major accident investigation team was called to the scene taking several hours to conduct their investigation as the traffic from I-5 had to be diverted from exiting the freeway at Louise Avenue.
Meanwhile an hour later another fatal accident occurred when a westbound driver going over the transition ramp from the Highway 120 Bypass to northbound I-5 went off the side of the ramp and crashed below. 
That triggered major delays and forced the 120 Bypass to northbound I-5 to be closed until 1:25 p.m. while Caltrans made emergency repairs.
Meanwhile a vehicle crashed going off the Eleventh Street approach to the bridge that carries traffic over the I-5 so it can merge with the northbound lanes.
Shortly afterwards there were other serious injury collisions on the freeway including one on I-5 at Kasson Road and another on I-5 north of Louise Avenue
One Manteca motorist said he was moving at only one to two miles an hour from Tracy to Manteca and was surrounded by big rigs front and back and on both sides of his car. The only traffic moving faster   were motorcycles that were lane splitting.
 A Tracy couple said they were forced to drive north on Tracy Boulevard and head into the Delta to take the back roads to make a noontime appointment in Stockton because of the I-205 backups.
State officials said traffic conditions were made worse Friday by motorists heading north for the weekend to view the Monday eclipse in Oregon.

To contact Glenn Kahl, email gkahl@mantecabulletin.com.