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Posted at 11:00 AM ET, 03/18/2009

Another Pothole in Paradise

By Ann Posegate

Wx and the City

* Will Today's Warmth Last? Our Full Forecast | The Iditarod *


A driver's worst enemy -- a pothole. Courtesy D.C. Department of Transportation.

As CWG's Ian Livingston noted last week, the D.C. Department of Transportation began on March 11 a month-long crusade to fill the city's potholes. Deemed "Potholepalooza," the initiative aims to have all reported potholes filled within 48 hours (typical turnaround is 72 hours). Based on some of my bike rides lately, our streets sure need the help.

Why do these potholes form? The answer has to do with the physical properties of water -- including the fact that, unlike many other liquids that contract when they freeze, water expands -- and the fluctuating temperatures of early spring.

Keep reading for more on potholes and an update on D.C.'s efforts to fill them.

The hydrogen atoms between water molecules (each water molecule contains two hydrogen atoms and one oxygen atom) like to link together by forming hydrogen bonds. In liquid water, these bonds are fairly weak and can break and form again and again (here's a video of liquid water in action). However, as the temperature decreases, water molecules slow down, stay bonded together and, if cold enough, eventually freeze into a very unique and stable lattice structure.

March is a great time to form if you're a pothole. Rain and snowmelt seep through cracks in a street and collect in the soil below. Freezing temperatures cause the water to turn into ice, which expands, pushing the pavement up. When temperatures rise again, the ice melts, the liquid water evaporates or seeps into the ground, and a hole is left underneath the pavement. When a vehicle drives over this weak spot, the pavement cracks and drops into the hollow below and voila: a pothole -- not to be confused with a sinkhole or utility cut -- forms. Check out this graphic to see the entire process.

How is Potholepalooza doing so far at filling in these pesky potholes? Within just the first week, over 1,200 potholes have been filled -- 518 on Monday alone. If the weather is just too boring for you this week, you can monitor the city's daily pothole-filling progress at DDOT.

If you happen to hit a pothole with your car and you notice steering problems, low tire pressure, or visible bulges or blisters on your tires, it is a good idea to have a professional check your vehicle for damage and make any necessary repairs. And if you're a cyclist, be especially cautious in avoiding potholes.

Even though potholes are a nuisance this time of year, just be thankful we don't experience frost heaves in D.C....

See Ann Posegate's previous Wx and the City posts.

By Ann Posegate  | March 18, 2009; 11:00 AM ET
Categories:  Posegate, Wx and the City  
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Comments

Ann, interesting and informative post.

I wonder whether DC has an efficient system for identifying the location of potholes and timely mechanisms for repair. Boston has a Google based mapping system which shows the location of known potholes and enables submission by the public of those not yet identified.

It's too bad roads are not constructed in the first place to minimize the chances for potholes to develop. I believe there are techniques for proper drainage and road surface materials that will largely prevent formation of potholes. I do not know the actual increased costs in road construction, but it seems to me that it should be cost effective over the long run. Any engineers out there who can comment further on this??

it

Posted by: SteveT-CapitalWeatherGang | March 18, 2009 11:32 AM | Report abuse

D.C. can be NOTORIOUS for ignoring potholes. Once,during the 1970's, a pothole on Connecticut Ave. near the Washington Hilton was there so long, I was beginning to think the USGS should begin monitoring it for volcanic activity!

Arlington County does a far better job. Even so, I suspect some potholes will go unrepaired due to all these economy related 'service cutbacks'.

Posted by: Bombo47jea | March 18, 2009 11:58 AM | Report abuse

Interesting. I always thought potholes were formed by horizontal expansion of frozen water in cracks -- I never thought about the vertical motion.

Perhaps my notion can be used to explain potholes on bridges, where there is nothing underneath the pavement to absorb water. (I think.)

I expect there are road construction techniques that are more resistant to potholes, but guess they are more expensive overall, even considering repair costs.

I note that potholes do not form on most of the road surface. Perhaps analyzing why this is the case would be useful in setting road construction techniques.

Posted by: Bitter_Bill | March 18, 2009 2:18 PM | Report abuse

I hope MoCo is doing something like this. Driving to work on Connecticut Ave from DC to Aspen Hill is like an obstacle course, and it has been for years. Thanks to that stretch of road, I've had to have a ball bearing replaced in one of my front wheels and popped two tires far sooner than I should have.

I think it's safe to say that there will be no potholepalooza in MoCo. Maybe they'll just throw some steel plates over the big ones and call it a day.

Posted by: LaurainNWDC | March 19, 2009 12:46 PM | Report abuse

The comments to this entry are closed.

 
 
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