The sharp eyes of a patriot, otherwise termed an ‘opposition’, detected worrying security concerns in one of the three sub-grade intersections built by Governor Willie Obiano of Anambra State barely five years ago.
Fondly called ‘flyovers’ the Aroma stationed reinforced concrete structure reportedly set the state back by N5 billion of taxpayers’ toils. However, the issue presently is not about the seemingly inflated cost of construction but rather the safety of the same taxpayers that ply within and around the evidently defective structure.
Had those in charge of environmental safety been up and doing, it wouldn’t have taken a passerby to detect such huge defects and taken to social media before the government concerned had to make a hurried visit through the Commissioner for Works, Engr. Marcel Ifejiofor.
The main reasons structures fail range from bad design, to faulty construction, through foundation failure, extraordinary loads, unexpected failure modes or a combination of all these indices. However, structural failures do also occur due to natural disasters such as earthquakes, floods, hurricanes, cyclones and fires.
Whenever a structure fails, the Engineer will always ask these basic questions –
1. Why did it fail?
a. Was the failure due to limitations of human understanding ?
b. Was it due to human error or negligence?
c. Or perhaps due to greed?
d. Was the failure due to an unexpected load?
But hardly do engineering structures fail without giving outward signs unless failure from natural disasters as mentioned above.
Such outward signs include crackings. Cracks appear in structures when there is movement or shift beneath the foundation of the structure caused by:
clay shrinkage, land slip, vibration, subsidence, settlement, heave, sway, etc.
Cracks do appear also from foundation failure due to the decay of soft clay brick, concrete erosion due to chemical contaminants, decay of the building fabric, due to woodworm, rust, and so on.
Moisture movement that causes materials to expand or contract.
Thermal movement that causes materials to expand or contract as temperature increases or decreases. Inherent defects, particularly in historic structures. Faulty or damaged drains. Suspended structures such as floors that deform under load. Tree root growth. Absence of foundations in older buildings. Etc.
All these indicate that failure of structures, particularly concrete structures are inevitably associated with humanity. However, it becomes a different ball game when such failures are traceable to avoidable human factors.
Unlike the other two of the three most popular professions of Medicine and Law, the Engineer has no liberty for failure.
As far back as 2200BC, the Code of Hammurabi was written and later translated thus:
1. If a builder builds a house for a man and does not make its construction firm and the house collapses and causes the death of the owner of the house – that builder shall be put to death.
2. If it causes the death of a son of the owner – a son of that builder shall be put to death .
3. If it causes the death of a slave of the owner – the builder shall give the owner a slave of equal value.
4. If it destroys property – the builder shall restore whatever it destroyed and because the builder did not make the house firm, shall rebuild the house which collapsed at his own expense.
5. If a builder builds a house and does not make its construction meet the requirements and a wall falls in – that builder shall strengthen the wall at his own expense.
This ancient code may have been extremely harsh but that is the severity of the cross structural engineers should carry in order to be extremely thorough and professional in designing and building structures for societal purposes.
The bridge in question has so many aesthetic defects, ranging from antiquated design to very rough construction as well as ignoring acceptable highway construction standards of having the major traffic go under in such sub-grade engineering beauties.
Besides aesthetic failure the added load of the twinkling stanchions that were suspected weren’t part of the original design but we’re added as an after thought to improve the aesthetics, especially at nights, presented a structural stress such antiquated construction didn’t need.
It will take a professional to decipher that the design was faulty when barricades were constructed to bar heavy-duty vehicles from plying on top of the bridges. That singular act rendered the intention of building the structures in the first place completely defeated.
The barricades meant the experts that instructed the erection knew the bridges faced dangerous movements owing to vibrations from heavy-duty traffic. But it was just a matter of time and smaller vehicles will accumulate same mobile load effects on the poorly constructed monuments of impending disaster.
Going deeper, cracks in structures, depending on level, weaken the structure and could lead to eventual collapse. Let’s take a look at standard code of practice regarding cracks.
1. Hairline cracks: Less than 0.1 mm in width. No repair action required.
2. Fine cracks: Up to 1 mm in width. Generally restricted to internal wall finishes. Easily treated using normal decoration.
3. Cracks easily filled: Up to 5 mm in width. Not necessarily visible externally, but doors and windows may require adjusting to prevent sticking. Can be masked by suitable linings.
4. Cracks that require opening up: Widths of 5-15 mm. Weather-tightness and service pipes may be affected. External brickwork may need repointing or, in some cases, to be replaced.
5. Extensive damage: Widths of 15-25 mm. Windows and door frames become distorted, walls lean or bulge noticeably. Requires breaking-out and replacement of wall sections.
6. Structural damage: Widths greater than 25 mm. Beams lose their bearing, walls require shoring, and the structure is generally unstable. May require major repair works.
All the cracks noticeable from the videos circulated of the ‘flyover’ in discuss range from 4 – 6.
Additionally, horizontal cracks are more dangerous because they indicate a major component of the construction is failing and hence presents safety concern. And there are horizontal cracks in the structure in question.
It is therefore not enough for Gov Obiano to start sounding politically correct by assuring his bridges are safe. They should be made safe by involving all professional processes of repairing such huge structural defects or face the danger of criminal charges should any tragedy befall within or outside his tenure.
As it stands now those defects can still be arrested.
Tai Emeka Obasi is a civil engineer, football and political analyst, an author and scriptwiter with so many titles to his name.