Osogbo LAMECO Flyover Collapse: Failed Soil Compaction, Not Vandalism, Caused Structural Failure – Engineer Alleges

The partial collapse of a section of the LAMECO Flyover in Osogbo, Osun State during Thursday’s rainfall, July 23, 2026, is a serious engineering failure that demands urgent, transparent, and technical response, not political deflection.

Based on standard engineering practice for a structure of that height and loading, the Osun State Government ought to have conducted a minimum of four compaction tests during construction for 100% compaction.

Compaction test is a test done to check how well soil, gravel, or other materials have been pressed together during construction. When building roads, flyovers, ramps, or building foundations, loose soil traps air and water. If the soil is not properly compacted, it will settle, sink, or cave in later.

Compaction testing is required at least every 150mm layer . This is non-negotiable for the integrity of any road or ramp structure. Unfortunately, available information indicates that Compaction tests were not conducted by the Osun State Ministry of Works and the Contractor during the construction .

The question of vandalisation or sabotage, as the state government is struggling to establish, should not arise at all. Raising it now is a political statement aimed at whittling down the embarrassment and public backlash caused by the partial collapse. This is an engineering challenge, not a political one.

In the interest of public safety, I challenge the Osun State Government to immediately present its compaction test results, layer by layer, to independent assessment engineers for verification. Without verifiable data, public trust cannot be restored.

Furthermore, the Osun State Government will need to conduct proper compaction tests on the ramp now to assure the integrity of the structure. It is obvious the compaction requirement has failed. The ramp was not well compacted. What that means in practical terms is that the asphalt on the bridge will need to be dug out and the sub-base properly re-compacted and reconstructed. If this is not done, we should expect further caving of the asphalt in other areas of the Lameco flyover. I also feel we should ask the Osun State Ministry of Works officials why they opted for laterite for the Ramp sub-base as against sharp-sand like it was done in the case of Olaiya Flyover. For bridge ramp construction, sharp-sand is superior to laterite because it offers better drainage, stable compaction with minimal risk of long-term settlement under vehicle loads, and minimal moisture-induced volume changes.

This is an issue of life. The Osun State Government must not handle it with levity as it is also being rumoured that the Abutment is structurally challenged too.

The developments in Osun are frightening. COREN, the Nigerian Society of Engineers, and all relevant engineering associations should be worried and must get involved immediately to protect professional standards and public safety. This concern is heightened by the fact that the contractor handling the project, Kimzee Global Investment Ltd (RC-1324581), is not COREN certified. It is a company known primarily for art and craft skills acquisition for trainings.

I call on the Osun State Government to act swiftly, engage independent engineers, and put the safety of citizens above all other considerations.

Signed,
Engr. A. Ajayi, MSc, FNSE