Accident High Severity Resolved

CHP : Severe traffic alert on CA-4 Westbound west of San Joaquin County Line (Byron). Lane affected. Expect delays.

A high-severity accident was reported on CA-4 W near Contra Costa on September 12, 2026 at 5:37 AM.

Road

CA-4 W

Area

Contra Costa

Address

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Started

Sep 11, 10:37 PM

Last Updated

1 month, 2 weeks ago

Sep 11, 11:00 PM

Resolved

Sep 12, 5:00 AM

Coordinates

37.8914, -121.5702

Update History

1 observations

CHP : Severe traffic alert on CA-4 Westbound west of San Joaquin County Line (Byron). Lane affected. Expect delays. Sep 11, 10:45 PM

Source: 511_sfbay · ID 511.org/1548294 First seen Sep 11, 2026 10:45 PM