Amplified

• Added lanes to, say
• Increased (gap)
• Added a lane to
• Made broader
• Like some highways after construction work
• Diversified
• Went from two to four lanes, say

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Widen \Wid"en\, v. t. [imp. & p. p. Widened ; p. pr. & vb. n. Widening .] To make wide or wider; to extend in breadth; to increase the width of; as, to widen a field; to widen a breach; to widen a stocking.

Wiktionary Word definitions in Wiktionary
vb. (en-past of: widen )