The California Vehicle Code requires an oversize load permit for any load exceeding legal weight or dimensions. That would be loads exceeding 14' high (Section 35250), 8'6" wide (Section 35100), 40' long (single), 65' (truck/trailer), 75' (multi trailers) (Section 35400 & 35401), or 20,000 lbs/axle (Section 35550).
The Los Angeles County Department of Public Works issues the Transportation Permit for the City of Signal Hill. The permit may be obtained over the Internet at the link below.
https://dpw.lacounty.gov/spats/public/tpap.cfm