Fig. 1 — The San Diego freeway frame, simplified: five named corridors, drawn as a diagram, not a navigation map.
The frame: five corridors, one valley
San Diego County's freeway system hangs on five routes, and this desk uses them as its crash-education frame:
- I-5 — the coast route. It runs the length of the county from the international border through downtown San Diego, La Jolla, and Oceanside.
- I-805 — the inland twin. It splits from I-5 north of Mission Valley and rejoins it near the border, giving the county two parallel north-south spines.
- I-8 — the east-west spine. From the coast at Ocean Beach it runs east through Mission Valley and out toward the desert.
- I-15 — the interior north-south route, meeting I-8 at the Mission Valley interchange and running north out of the county.
- SR-163 and SR-52 — the connectors: the Cabrillo Freeway through Balboa Park toward I-15, and the San Clemente Canyon route from La Jolla east to Santee.
Where the conflicts concentrate
The geometry that deserves the most attention is the geometry of decision-making: merges, weaves, and interchanges. The 5/805 split and merge bracket the valley. The Mission Valley weave puts the 5, 805, and 8 within a short stretch of each other — exits and merges a mile apart, with lane changes stacked on lane changes. The 8/15 crossing is the county's interior interchange. None of this is a statistic; it is geography anyone can verify on a map — and it is where attention belongs.
The speed law applies everywhere
Where the state has posted 70, that is the ceiling — and Vehicle Code §22350, the basic speed law, is the rule underneath: no speed is lawful that is not reasonable for the conditions, whatever the sign says. The sign is a ceiling; the conditions set the duty. The freeway moves at 70 only when 70 is reasonable.
Which agency patrols which road
The CHP patrols the freeways and the unincorporated county roads; SDPD patrols city streets. The reporting file maps the agencies, their offices, and the reports each one writes.
No statistics here. This desk does not publish crash counts for these corridors. SWITRS-derived numbers belong to the CHP's public data, and this desk publishes none of it until it has fetched and cited the underlying data itself. The frame above is geography — verifiable by any reader on any map.