Under California Vehicle Code (CVC) Section 29000, what cargo securement rule applies when transporting traffic control equipment on open flatbed trucks?

1. Loose equipment may be piled loosely if side stakes are installed.
2. Equipment only requires tie-downs when traveling on interstate freeways.
3. All cargo must be securely tied down or contained to prevent spilling or shifting.
4. Traffic cones are exempt from cargo securement rules due to their rubber bases only.