Kenya Government has recently proposed to construct a 700km boundary wall to separate Kenya from Somalia.
Assuming its a stone wall, the surface area will be 700km x 7m height=4.9 million m2 of surface. Assuming the average rate per m2 for wall construction of kes 1000 per m2, this will budget at kes 4.9 billion.
Source of stone.
Juja area of Nairobi is the source of machine cut stone for the whole of Kenya, sometimes spreading to parts of Uganda and Tanzania. Other parts of Kenya have machine cut stones but the stones are too hard to cut hence unfeasible, with low production eg Kiserian, Kitengela, Athiriver, Kedowa-Kericho and Coast region.
The Juja stone is quite soft, hence easy to cut using machines. Cost of each stone varies from kes 55 shillings per piece in 30 km radius from Juja to kes 100 per piece in areas 500 km away from Juja.
Assuming construction time of 30 minutes for 1 m2 of stone, 4,900,000m2 of stone will take 279 years to construct, day and night . Therefore, unless mechanization process comes in whereby time for 1m2 of stone surface is shortened to say 15 minutes, the time taken will be 15 minutes x 4,900,000m2=73.5 million minute=1.2m hours=51,000 days=139 years.
Therefore, stone wall will take literally forever to construct, hence a faster method such as razor wire chain link fence on concrete posts would be more appropriate.
The Great Wall of China, which is 6000km long took approximately 1700 years to build from 220BC to 1700 AD during the Ming Dynasty (1368-1644).
The wall was constructed to keep China safe from Mongolians led by Genghis Khan, which was not as successful since Genghis Khan and his army demolished part of it, which was later rebuilt using stronger materials.
USA-MEXICO Boundary wall.
This wall is 3000km long and constructed using barbed wire , chain link fence, steel and concrete posts.
The fence is estimated to cost usd 49 billion.
Assuming its 7 meters high, the surface area is 7m x 3000km=21million m2.
Cost per m2 =kes 200, 000 per km.
The Kenya-Somalia wall budget is kes 23.6 billion . This is roughly kes 4,800 per m2 which is enough to construct to completion, including watch towers,gates, telecommunication equipment and maintenance.
Francis Gichuhi Kamau, Architrect.