Hawaii DOT Combats Landslide on Pali Highway Resurfacing
Turning a Challenge Into a Positive: Hawaii DOT Resurfaces Pali Highway Ahead of Schedule Despite Landslide
Large construction projects are complex as there are many moving parts. Because of this, they rarely go exactly as planned. Things were going smoothly on the Pali Highway resurfacing project around Honolulu, Hawaii, when a sudden problem arose. Ultimately, the Hawaii Department of Transportation (HDOT) turned the unexpected challenge into a positive.
The Pali Highway resurfacing project had been on the books for 15 years prior to its start date in December 2017. However, funding was not available. When funding arose, HDOT was clear on what needed to be done.
The project’s parameters include repaving five miles of the Pali Highway, which sees average daily traffic of 65,000 vehicles (users are primarily commuting to and from work as well as tourists). An improvement to lighting was also a major element of the project. “The lighting was poor and broken down,” says Ed Sniffen, Deputy Director for HDOT Highways Division. “Eighty percent of the lights along this stretch of the highway did not work and pole bases and conduits were unworkable.” In order to improve the lighting, the project called for installing 324 new poles and 456 light fixtures.
Other aspects of the project include updating crash barriers, installing communication conduits to connect fiber optics, and creating traffic counting systems. “The purpose of this is to determine the volumes going through the corridor, so we can adjust the signals and make traffic flow more efficiently,” says Sniffen. A high friction surface treatment is also being implemented.
A Landslide Will Bring It Down
The project was moving along just fine when disaster struck. There are significant high slopes in the area. The area is part of a rainforest. “It rains every day and night,” says Matt Morita, Project Engineer for HDOT. The rain is also unpredictable, and one never knows when it will rain and how much.
Put these two conditions together – high slopes and rain – and issues can occur. Rocks trickle down off the slopes and on to the highway. The trickle turned into a torrent and chunks of rock, the size of cars, came down on the highway. Not just one chunk. It was a landslide.
When it was over, 20 truckloads of debris had to be removed to clear the road. Thankfully, the landslide did not cause any injuries, but the straightforward job became more complex.
In retrospect, Sniffen says the landslide had benefits, “The overall project schedule is going to be five months shorter.” This is because the original plan was for the contractor to have limited access to the highway to allow for traffic to be minimally impacted. However, due to the landslide, the contractor had 24/7 access to the roadway. “The public understood we had to do something significant,” says Sniffen.
Because a contractor was already onsite, procuring services was simplified, and HDOT was able to respond to the landslide very quickly. In the interim, Morita, Sniffen, and the HDOT team developed a plan to rebuild the upper slope to try and ensure no future incidents of falling rock would cause injuries.
While one part of the route was opened with two days after the event, another section was completely shut down from February 2019 to September 2019. Fortunately, there are two parallel routes (an upper and lower) and a coastal route that service the area, so commuters were not completely inconvenienced.
Of course, the extra work that was required due to the landslide meant more money. Sniffen estimates the landslide added $27 million to the original budget, which was $70 million. The federal government is primarily financing the project (80 percent) with the remainder coming from the state.
The budget was also originally amended when the decision was made to use stone matrix asphalt (SMA). “We switched to SMA because it has more strength due to the larger aggregates which lock in and are in contact,” says Sniffen. SMA asphalt also has additional fiber which gives it more flexibility, strength, and durability.
“We’ve used it before and found that the pavement can go 15 years with no cracks as compared to other asphalts which are cracking after three to seven years,” says Sniffen. The additional time where no maintenance will be required makes the extra upfront costs worthwhile.
Added Safety Elements Protect From Heavy Rainfall
Working in an area where rain is so prevalent is clearly a challenge. Morita notes, “I’ve never seen a construction project with as much rain.” He credits the contractor for working around the elements, “The contractor did as much as he could to work around the rain and be flexible,” says Morita. “The contractor also worked in the rain whenever possible.”
Another safety element – in addition to the repaving and lighting – is the high friction surface treatment. This was implemented to increase grip on the road that can get slippery due to all the rain. “There’s area along the route that has a hairpin turn where drivers don’t always slow down,” says Sniffen. “So, we increased the friction to enable drivers to more safely navigate the area.”
For past HDOT paving projects with finish elevations, the contractor had to manually set elevation increments, which created a greater chance of error. For this project, GPS was used to automatically pave to the correct elevations, which resulted in positive drainage and no ponding. This makes it safer for commuters. To minimize handwork, slip forms were used and enabled construction crews to work significantly faster.
As anyone in the construction field knows, sometimes obstacles arise and a project is thrown off. In the case of the Pali Highway resurfacing project, a major obstacle was overcome and ultimately turned into a positive. Commuters and tourists alike now have a modernized route to ensure efficiency and many safety improvements – including emergency protection to help with future landslides. The project allows commuters to have a better driving experience that is safer, smoother, and more efficient.