A four-year project to widen Haleakala Highway will open to drivers today.

The $31.8 million project widened the highway from three to four lanes for a 5.5-mile stretch, from Hana Highway to the Pukalani bypass road. The second and final phase of the project, which was started in 2004, will open at 3:30 p.m. today after a dedication ceremony, The Maui News reported yesterday.

Drivers will have two new downhill lanes on the highway, and there will be new traffic signals at the Hali'imaile and Keahua road intersections. Other improvements include a grass median, an emergency escape ramp and upgraded guardrails.

Morning contraflow traffic will be discontinued starting tomorrow. Instead, drivers on old Haleakala Highway, who were previously able to "free flow" onto the highway during morning rush hour, will be required to stop before turning left to head downhill on Haleakala Highway. Uphill traffic will be allowed to stay on the highway instead of being diverted through Pukalani town.

State Department of Transportation Director Brennon Morioka said the project should reduce traffic congestion.

"At the end of the day, we hope to help each commuter spend more time at home with their families and less time sitting in traffic," he said in a statement.

A dedication ceremony will be held at 2 p.m. today on the new highway. To get to the ceremony site, turn off the highway on to Hali'imaile Road. Then, after about 100 feet, turn left and follow the cones to the project area; drive on to the new downhill lanes; and proceed about 1.5 miles to the intersection with Keahua Road.