Railway Ballast and its Maintenance
By Rainer Wenty and Fabian Hansmann
Ballast is the load-distributing link between the track skeleton and the subgrade. Subjected to enormous stresses, ballast often becomes the weakest link in the chain of track components. Interacting with the subgrade, it considerably affects the service life of the entire track system which makes it a cost driver. Over time, both composition and characteristics of the ballast bed change due to mechanical stresses, weather influences or external fine particles. These changes may have different causes, their negative effects, however, are almost the same.
The early detection of ballast fouling allows planning undercutting and prevents durable damage to the remaining track components. Numerous methods can be applied to detect ballast fouling. Many of them involve considerable efforts. This paper provides an overview on the diverse methods and shows how innovative track geometry analysis contributes to the reproducible detection of possible trouble spots at an early stage. This kind of pre-selection makes it easier to inspect certain track sections in detail, reduces costs and enables monitoring entire networks. Undercutting cleaning enables durable quality increases in the identified spots.
Today, undercutting cleaning systems must meet diverse requirements. By correct application of ballast undercutter cleaners the resulting ballast quality can be assessed as being superior to the placement of new ballast. In particular, reviews of the sieve analysis of cleaned ballast show the excellent gradation results that can be obtained through ballast cleaning. The low track geometry degradation rates and the extended service life of tracks compensate for the cost involved in ballast cleaning operations.