Related Clues:

• Proceeded through a traffic jam, e.g.
• Slowly ascended
• Went on all fours
• Snuck
• Slithered
• Edged
• Approached with stealth
• Slunk
• Advanced very slowly
• Was sluggish?
• Moved on hands and knees
• Proceeded with caution
• Emulated a cat burglar
• Got high gradually
• Moved steathily or cautiously