Why Hawaii's Roads are Bad

by Amy Brown PhD, WAPNFFS 
 
I was the private citizen attempting to get Senate Bill 2603 passed about 5 years ago to improve Hawaii’s roads. The bill was promptly killed in the first hearing. That red flag fueled me to search for the real reason why we have so many potholes in Hawaii. The resulting op-ed that now follows debunks several road myths that we have been led down the road to believe. 

Myth #1: The Rain Causes Potholes!
False: It’s the road. A 3/18/08 Honolulu Advertiser article stated, “Hawaii’s tropical climate wreaks havoc on the roads, city officials say, with hot, dry weather followed by wet conditions.” A road engineer stated, “If your roof is in good condition, it will not leak. Same with the roads.” The problem is that our roads “leak,” and the reason the roads leak is because water is getting through the asphalt cracks and undermining the approximate 6 inch base layer beneath, or the water is getting under the road due to lack of adequate drainage. I contacted the newspaper with this fact and yet they still perpetuate the "it's the rain" story. 

The biggest reason for these potholes is that there are not sufficient inches of asphalt over the base layer. Roads with thicker asphalt coverings last approximately 15-20 years, and concrete roads last 30-40 years. Numerous factors come into play such as traffic volume, load (vehicle weight), climate, sub-grade support, material mix for asphalt and base, road design, construction quality, maintenance, etc.. Cement roads are more expensive and have unique construction requirements, but H-3 is pothole-free. 

Hawaii's outdated standard for minimum inches of asphalt was 2 1/2 inches for commercial streets, and 2 inches for residential roads. Highways need more inches. Even though inches of asphalt is standard language used all over on the mainland, Hawaii's 1972 old standard was replaced by a complicated “formula based on numerous variables” that cannot be visualized. 

Nationally, the old standard averaged 2 over 6 inches, but the increased traffic and heavier vehicles have shifted that to 4 over 6 inches. Dave Jones, San Diego’s Field Engineer, stated that the minimum asphalt covering for San Diego city roads is 3 inches. Even though rain is scarce in San Diego, Jones said, “San Diego would never allow 2 inches on their city streets.” Jim Huddleson, Pavement Design Engineer in Oregon, said, “It rains here a lot,” but 3 inches of asphalt was not working for them so they switched to 4-5 inches of asphalt for residential streets, and 4-6 inches for commercial streets. 

The key is asking how many inches “each” are the asphalt and base layers. Otherwise, you might be given one number that sounds better because it includes both layers without revealing asphalt inch depth. In the interest of quality roads, the newspaper should investigate how many inches of asphalt were and are being used in current and future road repair jobs as these numbers are stated in all road contracts. A call to the city found that Keeaumoku Street, a busy commercial street, was recently repaved with only 2 inches of asphalt. Legislation should be passed requiring a minimum asphalt standard of 3 inches or more. 

Another problem is spreading limited road repair money by using even a thinner layer of asphalt or not replacing the base under the asphalt. The latter process called road “rehabilitation” (replacing up to 15% of the base) or “reconstruction” (removing more than 15% base) is very expensive. However, a road engineer said, “If you simply place new asphalt over an old asphalt road without correcting a bad base, it’s like putting lipstick on a pig.” Yes, Obama got the famous quote from Hawaii based on our roads. 

In addition to thin asphalt covers and faulty bases, it is important to ensure that both road and pothole road repairs include compacting or pressing down the layers in order to squeeze out the air. More than 8 percent air causes makes the asphalt permeable to air and water. To avoid this, each of the asphalt and base layers need to be compressed with a machine roller. Compaction tests consist of drilling a hole into the road and sending the core to a private lab for analysis to confirm adequate construction. These last two steps are sometimes compromised in Hawaii.

Even correct pothole patching requires smaller rollers or a hand held hammer to compact the new asphalt so that is it level with the surrounding pavement (rather than leaving a bump), that should then be covered with a seal to ensure no water enters between the old and new asphalt. This is not done in Hawaii. I was told that car tires compact the asphalt. Quality control measures need to be enforced.

Myth #2: The City Has Equipment to Maintain the Roads
False: Although the city fills potholes, about 90 percent of city road repairs are contracted out to private corporations. Coplaners (millers) are large machines that grind off the old asphalt before a new layer can be put down. If the base is bad, they go deeper to grind up the base. Otherwise, the new asphalt covering will collapse as the base continues to fail. Coplaning machines come in small, medium and large sizes ranging from 18 inches to 8 feet wide in their ability to strip off old asphalt. The city has one “small” coplanar that is only capable of taking off 18 inches across (wide, not deep) at one time. This coplaner works primarily on sidewalks to allow wheelchair access.

Myth #2: It’s a War on Potholes!
False: It’s a war, but it’s the wrong war. Potholes are severe signs of pavement failure. They are due to thin asphalt surfaces (2 ½ inches or less) and/or a bad base. Water gets through the thin asphalt or underneath due to lack of drainage, and undermines the base below. The base partially dissolves and causes the surface to cave in creating a pothole. Cracks, alligator skin where chunks pop out, and potholes are signs that the road has “failed.” Extensive potholes are a sign of severe structural problems that become public safety hazards.