Since 2005, Kenyan has undertaken numerous road infrastructure projects to accommodate or ease our country’s ever-increasing traffic flow in urban areas. In Nairobi alone, there are at least four major road expansions that are either ongoing or have recently been completed. Some of these projects include the Western Bypass, Northern Bypass, Nairobi Expressway and the Eastern Bypass. With this new construction has come an influx of overpasses, interchanges, and flyovers all designed to ease traffic into the CBD, aid pedestrian traffic, and reduce axle load damage on major roads through the city.
While it is commendable that subsequent governments have made infrastructure a priority, more can be done to ensure that our roads and highways achieve their service life with minimal maintenance, whilst keeping road users and drivers safe. Understanding key factors in design and construction that affect road outcomes will not only help save lives but also build better and plan for the future.
Inadequately designed roads
Road design consists of a variety of phases, which includes geotechnical and topographic surveys (traffic surveys are covered separately) that give rise to the roadway and pavement design. Roadway design consists of the actual corridor design including pedestrian and service lanes, intersections, stormwater drainage, and other elements of the carriageway. Pavement design involves the design of the road cross-section, including the materials used and their thicknesses.
Highway building design and technology has greatly improved in Kenya, especially on the back of the increased involvement of experienced foreign contractors who design and build projects themselves. However, it is still not unusual to find a road that hasn’t been designed satisfactorily which leads to further problems down in time. For example, if a geotechnical survey hasn’t been properly done, chances are that the subgrade will fail under vehicular traffic in some road sections.
Pedestrian and designated lanes for motorcycles and bicycle riders can also help to reduce some of the errors that have been witnessed, especially along major city roads.
Inadequate Traffic, Pedestrian and Economic Surveys
While a good design on paper goes a long way to improve a road’s lifespan, due consideration should be given to economic expansion both now and in the future for the said road. A good example of this is the Eastern Bypass in Nairobi which was until the recent dualling was a nightmare to use.
Another good example is the Outering Road in Nairobi’s Eastlands which is currently ranked one of the most dangerous roads in Kenya, with 44 out of 371 road deaths within the city in 2020. The road design is overly complex and outrightly unsafe in some areas, thus increasing the likelihood of driver-induced error. Sudden dead ends to lanes and a particularly strange loop near the former Taj Mall interchange are often pointed out as serious design flaws.
With any new road project, it is expected that the economy of the area will expand. For major highways, there is expected an influx of people, industries, and thus new traffic and axle loading. In fact, a lack of proper planning is a major reason why Kenyan roads don’t remain sustainable for too long. All these are considerations that should be in the initial feasibility study of the road.
Cutting corners and use of poor building materials
Road materials are the most important component of a long-lasting road. A common road design principle is that material should be hauled from as close to the construction site as possible. However, this isn’t always the case. A designer or contractor may opt for poor material nearer to the site to save on haulage costs. They may also cut corners concerning the actual pavement construction versus the design, for example, by not doing enough compaction, using less material volume, or building on a wet subgrade.
One way to counter conmanship during the design and construction processes is to ensure that everything during these phases is double-checked and supervised by a government agent and any omissions noted.
Inadequate road base or sub-base
The subgrade and road base are essentially the foundation of a road. Again, this comes down to good design and build. The essential elements of road-base and sub-base are excellent material, enough compaction to provide at least a 95% CBR (California Bearing Ratio) reading, and keeping these sections moisture-free during the road service life.
Using an unqualified contractor
Even with a good design, a road is only as good as the person who builds it. In Kenya, various incidents have been reported of unqualified contractors being awarded tenders to carry out major road projects. These contractors may lack the technical expertise, experience, or financial capability to carry out such major projects. As a result, they are more likely to cause omissions during the design or build processes.
Inadequate road furniture
Road furniture such as traffic signs, bumps, and crosswalks go a long way in ensuring that roads also meet their serviceability requirements. In many cases, the addition of road furniture in Kenya is mostly reactive, that is, after numerous accidents or complaints.
Is road construction in Kenya headed in the right direction?
With the government involving foreign contractors who are well experienced, Kenyan roads have received a facelift and are starting to look and perform much better. Good long-term planning which has been missing in the stakeholder process is starting to become a major consideration for upcoming projects. Government agencies area advocating a more sustainable process to building. Some ongoing projects yet remain to be seen whether they will achieve their desired performance.
