Safety and facts
Emergency care, photos, witnesses, report number.
California crash-injury education · desk no. 02
Every collision has a mechanics.
Every injury has a record.
Crashes produce predictable injury patterns — and paperwork that outlasts the pain. This desk explains the mechanics-to-injury chain, what to document, and how California's rules fit the file. No invented numbers, no advice dressed as information.
Call 911 for injuries. This site does not give medical or legal advice.
01
Collision geometry
02Restraint marks
03The record
The short version
Four facts that cover most of it.
Each carries its source. Every topic file expands on these.
- 01 / Geometry
Four geometries, four injury patterns.
Rear-end, T-bone, head-on, sideswipe: the direction of force decides which structures of the body take the load — and which injuries to expect.
- 02 / Restraints
Seatbelts roughly halve fatal-injury risk.
NHTSA's long-standing estimate: seatbelts reduce the risk of fatal injury to front-seat occupants by about 45 percent. Airbags add further protection.
- 03 / Reporting
Most injury crashes must be reported.
A written SR-1 report to the DMV is due within 10 days when a collision involves injury, death, or damage above the statutory threshold (Vehicle Code §20008).
- 04 / Filing
Two years to file a lawsuit.
Personal-injury lawsuits must generally be filed within two years of the injury under Code of Civil Procedure §335.1.
Index
Topics, in reading order
01Crash documentationThe four-part record that ties injury to collision: crash, medical, loss, statement.Read file →02California reporting rulesThe SR-1 report, the 10-day deadline, and the financial-responsibility frame.Read file →03Collision mechanicsSpeed, direction, delta-v: how crash geometry maps to injury patterns.Read file →04Rear-end collisionsThe struck vehicle accelerates; the head lags — the whiplash mechanism.Read file →05T-bone collisionsThe door is the only structure between the impact and the occupant.Read file →06Head-on collisionsClosing speed adds both vehicles' energy — the highest-force geometry.Read file →07Sideswipe & lane-changeLateral contact at speed — and the secondary events that follow.Read file →08Airbag & seatbelt injuriesRestraints save lives and leave their own, usually lesser, patterns.Read file →09Fractures after collisionWhen the load exceeds bone: patterns, imaging, and the healing schedule.Read file →10Insurance claim basicsThird-party and first-party claims, SB 1107 minimums, UM/UIM.Read file →11Frequently asked questionsThe questions this desk is asked most, answered from the same sources.Read file →12GlossaryEvery term this desk uses, defined once, plainly.Read file →
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Seat belts reduce the risk of fatal injury to front-seat occupants by about 45 percent.NHTSA — Seat Belts: Get the Facts
Why documentation matters
The record is the injury's second life.
Crash injuries live in records: the crash record, the medical record, the loss record, and your own dated notes. The documentation gap is where valid injuries get lost.
Start the crash file →Claim chronology
One collision. Four decision points.
History and exam
Symptoms, affected areas, findings, restrictions.
Course and function
Changes, referrals, work impact, daily limits.
Coverage and timing
Policy, correspondence, SR-1, UM/UIM, deadlines.
California time limits
“Two years” is not a safe calendar reminder.
California generally uses a two-year period for personal-injury lawsuits (Code of Civil Procedure §335.1), but shorter rules apply elsewhere in the file — the SR-1 report, for example, is due within 10 days (Vehicle Code §20008). Get fact-specific advice early.
Read the reporting rules →Authority is traceableRead the source.
Read the source.
See the boundary.
Every file distinguishes medical information from California legal and insurance guidance. The desk grounds itself in the statutes (leginfo), DMV and CHP guidance, NHTSA crash research, and professional-association sources (AAOS, CDC) — so readers can move from a plain-language explanation to the underlying authority.