Before you patch up your pothole, please read!

The gorges in front of where I live, and the forlorn sand heap left weeks ago by council, supposedly to fill the gorge up

The state of the Zimbabwean road network is no secret. It’s not even just a country joke, it’s a regional headache. One’s choice of car is determined by the number and depth of gorges on their daily route. In fact I could have been the proud owner of a 2021 Mercedes AMG E 63 E 4matic+ sedan, but because of the huge ditches in front of where I live, I still have to rely on mtshova.

Now a number of well meaning citizens have in the hope of prolonging the lifetime of their car’s suspension, filled up potholes with everything from grass, cow dung, stones, sand and various other organic and inorganic material. Some enterprising citizens have even started a business on this. On the intersection of Ridgeway and Stepps in Highlands, Harare, they put in bricks to fill in the potholes. Its fascinating to watch because in order to fit in a particular brick fragment, they have to dig up the road even more, creating an even bigger pothole. Here in Bulawayo as one enters Emganwini just after the railway line, the young men gave me an enthralling lesson on concrete mixes, with claims it’ll be a year before anyone has a problem with the road. 

Newly “rehabilitated” road in Emganwini, Bulawayo

@Bulawayo and Harare City Council, I present to you your newest recruits. The big problem with these concrete patches is that they cannot be resurfaced the way asphalt is. It will need to be cracked and redone when we finally get to properly rehabilitating our roads.

Obviously these remedies do not last, in less than half a day anything organic would have been squashed out of existence, and if it rains all the sand is washed away leaving gaping holes wider than before. Even the addition of cement as a binder will quickly fail at the join because of the abrupt change from a flexible (gravel) to rigid (concrete) pavement – ever noticed the shift as you drive on and off a bridge on the highway? One is also introducing water from this newly mixed concrete into the gravel layers below.

Now, how do these potholes form in the first place? As mentioned in this previous article, water is the biggest culprit in causing road failures. As we design these roads we try to redirect water away from the road, but water will always find a way.

Burst sewer cleverly avoiding the stormwater drainage

This article goes into detail about the primary causes of potholes affecting bituminous roads, the means of classifying them for repair purposes and suggested repair methods, specific for South Africa.

SO, how can we, the well meaning residents of Zimbabwe, assist in helping maintain our roads? Here are a couple of ideas. Please remember I am not legal council- just an engineer.

  1. Advocating for the incorporation of better road maintenance technology. For example, one of the things that exacerbates formation of potholes is the poor reinstatement of service trenches that are excavated through bituminous-surfaced roads. Instead of blocking a road for days, digging up a perfectly (somewhat) good road and poorly patching it afterward, there is a trenchless pipe technology that allows us to rehabilitate water, sewer and other services in a quarter of the time, zero disturbances to traffic and a fraction of the cost, particularly for deep pipelines with limited access. I will talk about this in detail in another article. Policy change is critical in order to adopt these new and efficient technologies. 
  2. Maintain the outside of our houses to allow proper drainage as explained in this article.
  3. (This one is tricky) Prevent the passing of heavy vehicles in residential roads. Boomgates, residents watch, a sit out at your councillors house until s/he gets the trucks to use a different route? 
  4. Timeous payment of city council rates- and demanding its accountability. Conversations should centre around a decentralised road revenue collection and disbursement fund. If the law needs to be changed on this, then sobeit. 

 

Doing the above will go a long way towards building a sustainable infrastructure system. You do not have to be an engineer to do this. The actual patching up of roads? Let your engineers do it. BUT before you start harassing them, ensure the funds and policy allow them to do so.

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