Residents and businesses are "really excited" about a long-awaited $1.773 billion extension of the Waikato Expressway, ministers say.

The four-lane 16km expressway will connect the Waikato Expressway to SH29 at Piarere.

Residents and businesses are "really excited" about a long-awaited $1.773 billion extension of the Waikato Expressway, ministers say.