- Although the preliminary engineering (by Gauff Consultants) had proposed 60kg/m, the NCIP SGR protocol required us to use 50kg/m.
- The Chinese standards TB 10082-2005 code for design of railways track specify that if speeds are 120kph and tonnage between 15-25 million tones (converted density volume), the 50kg/m is sufficient.
- The formula for sizing rails clearly show that 50kg/m is appropriate from the scientific point of view.
- The rail size (weight per meter length) is determined primarily by the axle load (other factors include traffic density, speeds etc.). The NCIP regional SGR axle loading is 25 tons which requires a 50kg/m rail.
- The wear and tear on these rails is a function of traffic density. The traffic density of Mombasa – Nairobi will be much higher than that of Malaba – Kampala, which is why Kenya decided to use larger 60kg/m rails. About 70% of the Mombasa port traffic is destined for Nairobi area.
a) The 50kg/m rail section is sufficient and cost effective for the projected traffic bearing in mind that rails wear and tear and are replaceable.
b) As good practice, rails are replaced after they have worn out and lost 5% of the weight.
c) Generally the rails constitute about 1.3% of the cost per route-Km.
d) 50kg/m rail is a common rail section used in China and therefore replacement rails are easily available.