Highways

HONOLULU – The Hawai‘i Department of Transportation (HDOT) has procedures to prepare for possible heavy storms and flooding. Those procedures include checks on drains and bridges, rockslide areas, and low-lying spots along freeways, highways, and roads. On Sunday, April 2, HDOT was not expecting the heavy rains over Honolulu that resulted in flooding on the H-1 eastbound near the Punahou offramp, the H-1 westbound near the Liliha overpass, and Nimitz Highway westbound near Iwilei Road.

HDOT crews headed out to the areas and completed the following actions:

H-1 eastbound near the Punahou offramp

• At approximately 1:50 p.m. Sunday, April 2, reported flooding was called into HDOT’s Tunnel Operations Center.
• Crew reached the area around 5 p.m. They were delayed by heavy traffic.
• Crew cleared the drains by 5:51 p.m. The drainage capability in the area was reduced due to filtering fabric installed for the nearby repaving project. The crew cut through the fabric to drain the water and cleaned gravel off the road.

H-1 westbound near the Liliha overpass

• Crew was notified of flooding at approximately 9 p.m. Sunday, April 2.
• The crew headed to the next flooded site, the H-1 westbound near Liliha. They cleared the drains in this location by 11:16 p.m. and followed up by washing gravel and debris off the roadway.
• Gravel and debris were cleared by 11:48 p.m.

Nimitz Highway westbound near Iwilei Road

• Crew was notified of the flooding near Iwilei Road at the same time as the H-1 Liliha flooding.
• Crew headed to Nimitz westbound near Iwilei Road after they cleared the H-1 at Liliha and reported the drain clear at around 12:47 a.m. Monday, April 3.
• Although the drain was clear, the water level remained high, blocking two lanes, due to the surrounding ground water level. The crew began vacuuming water from the road.
• At 3 a.m. the crew had vacuumed two truckloads of water and reduced the flooded area to half of the left lane.
• By 4:49 a.m. the crew reported all water was cleared.

To remedy drainage going forward, HDOT will remove filtering fabric and other best management practices (BMPs) from the work zone near the Punahou overpass whenever work is not being performed. The repaving of the H-1 eastbound in this area is expected to be completed within the next three months. The regular removal of BMPs will add an estimated $50,000 to the repaving cost.

HDOT has procedures in place to monitor weather reports for potential rainfall events and typically does storm preparations in event of a flash flood watch or similar weather warnings. Given the flooding that occurred in the Honolulu area, HDOT will adjust the threshold for storm preparations and will alert on call crews to prepare known flooding areas for any potential hydrological event.

HDOT will continue to post about events and conditions to our social media sites

https://www.facebook.com/HawaiiDepartmentOfTransportation/ and https://twitter.com/DOTHawaii

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