The state of Kenyan construction standards has come under scrutiny yet again following the recent collapse of a KSh100 million bridge in Kajiado just days after its launch by the County government. While a lot of blame has been thrown around including at ‘impulsive and unfair’ Mother Nature, the possible reasons for the collapse and the implications can be thought through rationally.
The most obvious reason for the collapse of this bridge would be a design deficiency. In the case of the Paai Bridge, this design deficiency became apparent only after it was too late. Media reports quoted Kajiado County Roads, Public Works, and Transport CEC Alex Kilowua as saying that one of the bridge piers “experienced a tilt”, brushing off claims by sections in the media that the bridge had been swept away by the floods.
For a Ksh 100m project that isn’t too large scale the expectation is quality, through – and – through, especially if the client is the government or any of its agencies. This means that the entire process should have been done to an exceptional standard, from the pre-feasibility and feasibility stages of the project including geotechnical surveys, right down to the actual construction and site supervision.
Structural Characteristics of the Kajiado Bridge and Possible Reasons for the Collapse
Similar to the provided illustration above, the Paai Bridge was connected by two abutments on each side and a central pier supporting vehicular load and traffic over the river valley below. According to the reports by the County CEC of Kajiado, this pier tilted causing the bridge to collapse, and this might as well be the case. The apparent reason for the tilt isn’t too obvious, but the most likely reason would have been that proper geological studies of the soil subgrade below especially under maximum drainage (bearing in mind a river valley below that frequently experiences flooding) were not done. Thus, the foundation bearing capacity of the entire area under maximum drainage and not just that under the central bridge pier should have been conducted.
Since such type of a structure was supposed to have been designed against maximum hydraulic loading from flowing water and sub-particle action, it is highly unlikely that the structure could have been swept away by the river torrents. The most likely reason was the settlement of the subgrade due to the increased drainage which caused the bridge pier to sink and thus overloaded the central stretch of the pavement support. This central support was also the main region of secondary support, with the two halves of this pavement support structure connected by bolted steel plates, thus making the collapse all but inevitable if proper design and construction were not done.
The Paai Bridge Collapse as a reflection of Quality Standards in Kenyan Construction
The Paai Bridge reflects more poorly on the procurement and oversight standards of state agencies such as county governments, rather than it does on the state of the Kenyan construction industry in general. Numerous top-notch building and infrastructure projects are coming up in Kenya, some examples being the Nairobi Expressway and the GTC, thus boosting confidence in our industry expertise. However, procurement standards in the government and state agencies that enable such faulty design errors to be carried forward to construction are what we should be afraid of, lest we lose more money and in the worst-case scenario, human lives.
