It is a requirement for every student under the Railway Centre at AAiT to undergo hands-on training also known as Professional Practice. This form of industrial training was focused on inspection and maintenance of Addis Ababa Light Rail...
moreIt is a requirement for every student under the Railway Centre at AAiT to undergo hands-on training also known as Professional Practice. This form of industrial training was focused on inspection and maintenance of Addis Ababa Light Rail Transit (AALRT). Inspection for alignment was mainly done using a track gauge ruler for the straight section and the versine method for curved sections.
As observed during the training sessions, ballast tamping is mainly carried out for correction of track level irregularities and it entirely involves manual labor. This turns out to be time consuming and tedious. Further, the damage to the ballast is evident both from site and literature. It has been found that ballast damage due to one tamping cycle is equivalent to approximately 20MGT of traffic and that approximately 2 to 4 kg of fines less than 14mm is generated per tamp for a single sleeper. Aggregates breakage causes fouling of the ballast which reduces the drainage and stability functionality of the ballast track. Among other observations made, was that the harder ballast material is mixed with weaker Scoria aggregates.
A number of new techniques are suggested based on literature on the current inspection and maintenance techniques. Video inspection has been suggested since it is fast, cheaper and provides on time information. Use of automated machines like stone blowing/ballast injection machines have been suggested to replace the impact tampers.
From this training, a number of gaps for study have been identified, such as; 1) A study on the level of fouling near level crossing and station section, and its effect on the drainage of the whole track should be undertaken, 2) The sorting out of weak ballast material like pumice and scoria at the construction phase should have been done. 3) The study on the mechanism of reinforcing ballast material to increase their resilience to tamping operations and heavy traffic loads should be carried out. 4) The use Stone-blowing instead of tamping should be studied. 5) Ways of reducing on the amount of aggregates used during railway line construction should be sought for both economic and environmental reasons.
