Friday, July 18, 2008

Potholes... Hawaii 2nd worst in the nation!

Why do we have so many potholes here on Oahu? Why are our roads among the worst in the nation? These are questions many of us ask when our cars hit yet another pothole.

There are two common types of pavements: asphalt and concrete. Concrete pavements are strong and durable. They are expensive to build. They are used mostly for freeways and for bus lanes. City streets are almost always asphalt pavements.

Pavements are structures. Like buildings carry people and furniture, pavements carry traffic. The weight of traffic makes the pavements flex. After millions of flexes, the pavement cracks. If it is not maintained before or as soon as it cracks, potholes appear.

A pot hole is a complete failure of the pavement. The more potholes there are, the more we conclude that proper pavement maintenance is not done. How does a crack become a pothole? With the help of water and traffic.

Water gets in the crack, traffic passes over it, the pavement flexes downward and that pushes the water upward which loosens and carries pavement material through the crack. Soon enough, a quarter-inch wide crack is a one-inch-wide crack and with enough rain and traffic, a large pothole can appear in just a few days.

What’s a good way to maintain pavements? There are many ways:

1: Crack filling, where crews have a system to patrol roads and fix them.

2: Chip sealing, where a special thin layer is added every 4 or 5 years while the pavement is in excellent or very good condition. This can keep a pavement excellent practically forever if it is done on schedule.

3: Pavement management system where each mile of roadway is in a database along with its condition and annual traffic load. Then, pavement repair and replacement jobs can be prioritized and done regularly and on schedule.

A good thing about asphalt pavements is recycling. The top layer of pavement can be recycled forever, which cuts down on the amount of stones we need to quarry. In addition, used tires can be added to the mix. This is very useful, because tire rubber is among the least biodegradable products.

When chipped and used in asphalt mixes, tires become 100% recyclable and they make pavements cheaper and quieter.

How bad are our pavements? The Honolulu Advertiser pointed out in March 2008 “Honolulu roads rated 2nd-worst in nation”.

The City and County of Honolulu is many years behind modern pavement practice. They use very old methods to patch potholes. This is a waste of labor and the results are poor.

They deploy very expensive ½-inch overlays on damaged pavement. This basically makes a road “look good” for a year or so. Like these two:

They do not have a pavement management system. They do not know how heavy traffic is on every road.

They do not use chip sealing and they do not do crack filling.

Basically, they are fighting a losing battle by using expensive band-aids on or very sick roads.

Honolulu’s pavements need a complete overhaul. More than one billion dollars is required to bring city road pavements to a near-excellent condition.