Two Friday morning accidents at the tail-end of the morning commute shutdown traffic in both directions on segments of the 120 Bypass that turned the freeway into a virtual parking lot for a period of time while creating backups on Highway 99 and Interstate 5 that lasted for hours.
The first accident involved five semi-trucks including several that spilled their loads shortly after 9 a.m. in the westbound lanes west of Union Road. That closed the Bypass heading west.
Then a short time later an accident eastbound on the 120 Bypass between the McKinley Avenue overcrossing in Manteca and Guthmiller Road/Yosemite Avenue in Lathrop closed the freeway to eastbound traffic. The second collision involved four vehicles.
The two accidents sent thousands of vehicles onto city streets in a bid to bypass the closures.
Significant accidents have been occurring on average every 36 hours on the 120 Bypass.
In an eight year period ending in December of 2018 there have been 1,700 accidents, 900 injuries and 17 deaths.
Caltrans is moving forward with a three-phase, $131.5 million solution to reduce the potential for collisions and ease traffic congestions in the 120 Bypass. The work on the first phase that will address the eastbound 120 Bypass backup by doubling the transition lanes to two for traffic headed to southbound 99 and replacing the Austin Road overcrossing to widen Highway 99 to allow for more efficient operational movement for merging is targeted to start in the fall of 2021.
Caltrans — in a study prepared to justify the project — noted your odds of getting in a collision on the 120 Bypass as you near Highway 99 if you are trying to head south toward Ripon and Modesto is six times higher than the statewide average. High traffic volume during the afternoon commute that sees in excess of 2,000 vehicles an hour trying to go from the eastbound 120 Bypass to southbound Highway 99 creates a backup for at least a half mile for a number of hours. The state notes that motorists — impatient about the delay — will use the fast lane or inside lane to travel as far as they can to the split and then cutback into the much slower moving traffic in the right lane. That leads to rear-end collisions and an accident rate six times higher than the average for a California freeway.
More than 60 have died on the stretch of freeway since the bypass of Old Highway 120 — Yosemite Avenue through Manteca — was first opened to traffic when Manteca had 24,925 residents and was roughly the same population as Lathrop is today. The bypass was originally opened as two-lane expressway with occasional passing lanes in each direction. That led to 36 deaths in the first 30 months the 120 Bypass was open before concrete K-rail was installed the entire length of the bypass to separate the lanes. When the bypass was expanded to full freeway status in the mid-1990s accidents dropped off until growth led to increased congestion on the transition ramp.
It has gotten to the point that in 2018 there was an accident every 15 hours at the interchange and freeway approaches that required Manteca Fire Department units to respond.