Rogbere and Pujehun bridges are accidents waiting to happen

AN OPEN LETTER TO THE DIRECTOR GENERAL, SLRA

Sir/Mr. D.G.,

It is with civic responsibility that I write this letter to you and call your attention to a problem that you may be already aware of. I say that you may be aware because you only recently assumed that office fully and as most administrations go these days, not all the bins are spilled over at handing-over time.

Mr D.G, as you will agree with me, these bridges were built in the late 60s and so are old and nearing their lifespan. At that time, traffic in Sierra Leone was limited to three wheeled cars and light four wheeled vehicles. This situation has changed dramatically with the advent of the ADT (All Duty Terrain) Vehicles and D9 dozers with carrying capacities of 40-60Tons. Not only are the axle loads the problem, but the Average Daily Traffic on these bridges has increased. Bridges are designed based on moving loads and the more the frequency, the amplitude of vibration and magnitude of these loads, the faster they attain vibration limits and so eventual failure due to non-elastic deformation of the concrete in them.

The issues around these bridges can be summarized as:

Lack of routine and periodic maintenance. I spent a few moments to get down my car and take pictures, some of which are shown here. It is clear that maintenance of piers, bridge seats and the bearings have been neglected for lack of words. Maintenance to these bridges is a thing of our forefathers. Civil Engineering school teaches that these should be annual at the least.
Lack of protective barriers for safe uses of the bridge. Due to previous accidents within the bridge proper and from approaching vehicles and due to shear lack of respect for public property by residents in those areas, the hard steel Armco barriers that are usually on both sides of the approaches are missing. This makes the water below the next landing point for any inadvertent driver who veers off course! Fearful as the thought is, this has happened to a couple of trailers and light vehicles. They had to be winched out using sophisticated methods and at high cost.
Lack of a clear sign of future improvement of the prevailing conditions. For the last years, there has been little interest in this bridge’s maintenance even though H.E, the President of this country uses that bridge regularly. This is dangerous to say the least. How can the lives of such important personalities be put to risk and for so long? Recently, we noticed that some cosmetic work is been done on the bridge using cement mortar by some unsupervised masons. What about the actual structural details that are the concern of the pedestrians and road users?
The bridges (Rogbere and Pujehun) are the only quick links to the other side; the North and the extreme South. Besides the principal function of connecting the two sides, these bridges have economic and geographic importance. Rogbere is the only land link from the West (the Capital area) to the North (the largest mineral deposit and foreign exchange earning areas) and ditto for international links between Guinea and the Capital Freetown. Large trucks, machines and land trains cannot possibly pass by Lungi ferry at this point and so this route is not an option. Similarly, the Pujehun bridge is strategic. Access to Liberia and the upcoming oil producing areas will need this bridge and traffic will predictably increase as economic activity increases in the next five years.

As the schematics below shows, impact on the piers due to any extraneous forces above or below water can cause failure at the foundation level that could also lead to major accidents above. And so, detailed studies must immediately be carried out to ascertain what needs to be fixed below to avoid structural failure as the Mabang bridge has today found itself.

The conclusion is that these bridges must be given priority status both because of the impact on movement of the Northern and Southern populations and also because of the economic losses these will occasion on the national economy if they were to fail. The North, our homeland will be de-capacitated for more than three months, and this is unacceptable in today’s Sierra Leone.

Four things need to be implemented immediately. Firstly, there must be buffer zones created in the approaches of the bridge for trucks that have brake failure not to run into the bridge superstructure but have a way of veering off. Secondly, the side protections must be reinstated urgently. Thirdly, the bridge must be cleared of all rubbish underneath and reconditioned at the bearings and piers. Fourthly, a second bridge must be built to reduce traffic loads on the one line, else a traffic light system must be installed.

Sincerely,

Francis H. Lahai, BEng, MBA, MSc.

Professional Civil Engineer and Manager.

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