Complex sentence: Route 3 begins at Route 66 in Middletown, and is a secondary, minor arterial road for its first up to its interchange with Interstate 91 in Wethersfield.
Split into simpler sentences: Route 3 begins at Route 66 in Middletown. It is a secondary, minor arterial road from Middletown up to its interchange with Interstate 91 in Wethersfield.