The Ethiopian Road Authority (ERA) is implementing various measures to improve capacity in the road construction industry to construct thin bituminous surfacings for rural roads. These initiatives include the development of a training programme on the design and construction of thin bituminous surfacings, and this Best Practice Manual. Training courses for engineers, technicians, foremen and operators have been carried out at the Alemgena Training and Testing Centre (ATTC). The purpose of these endeavours is to assist the road construction and maintenance industry in Ethiopia to provide more cost-effective and durable bituminous surfaced roads.
In recent years there has been a reduction in the use of thin bituminous surfacings in Ethiopia in favour of asphalt concrete. We had experienced a number of surfacing failures and thin bituminous surfacings had started to develop a poor reputation. When we analysed the reasons for this we discovered that there had been cases of inappropriate treatment selection, poor workmanship on site, and an inadequate general understanding of seal design. The existing technical specifications were insufficient and unclear.
The use of asphalt concrete surfacing instead of thin seals has led to increased cost of construction for our rural roads. This trend needs to be reversed in order for us to maximise the use of the resources we have available in the road sector in order to bring the maximum benefits to the rural population.
As a result we have begun implementing a skills enhancement training programme for local surface treatment practitioners. We have also produced this manual, which provides state-of-the-art guidance on the interpretation of standards, surface treatment selection, the design of thin seals, and their construction and maintenance in Ethiopia.
I trust that this manual will provide the essential information needed to guide our design engineers and our construction industry in the provision of appropriate and sustainable paved rural roads.
Zaid Wolde Gebriel
Director General of the Ethiopian Roads Authority