the People. In Isaiah 40:3 the way is to be "prepared" for Messiah: here, for His People.
cast up, cast up the highway. Compare Figures of speech Epizeuxis and Polyptoton. App-6. See note on "highway" (Isaiah 7:3).
Related Commentaries of Isaiah 62:10
Isaiah 62:10
10 Go through, go through the gates; prepare ye the way of the people; cast up, cast up the highway; gather out the stones; lift up a standard for the people.