# Long Term Effects of Reduced Track Tamping Works
## 3 Results and Discussion  
The evaluation of the different scenarios is executed with an economic comparison. All options provide a safe track as limits are always met so that a purely technical comparison can be done looking at the different quality levels, the quantity of maintenance actions and similar topics, but does not answer the question as to which of the maintenance regimes should be followed. The economic assessment based on total life cycle costs delivers an integral view of maintenance, service life and the involved costs. In this way, the long-term effects cannot only be depicted, but also monetarized. Doing so provides a sound basis for decision making in track asset management. We compare the scenarios at the point in time Q12018, technically as a first step in order to discuss the short-term effects of reduced track tamping: replacing the through-going tamping actions with spot tamping works as the single failure does not lead to additional single failures within a 10 year time period. Track maintenance costs decrease accordingly, but track quality also drops to a very poor level (SDLL 3.08 mm) compared to scenario 1 (SDLL 1.38 mm). Technical limitations due to track quality (speed restrictions or similar) do not occur, and the short term savings are equal to 2120 m of tamping minus the additional spot tamping length of roughly 240 m. Assuming some 20% per metre for the line tamping and five times higher metre costs for the single failure tamping, ballast maintenance delivers short-term savings of 16.3% or 18,400% in the 10 years analyzed. Scenario 2a shows that the \"spot tamping only\" strategy does not work in the long run: the growing number of single failures lead to both increasing costs in maintenance and massively reduced track availability, as track closures for the frequent maintenance interventions need to be provided. Additionally, through-going track quality runs beyond the safety limits. A standard deviation of more than 5 mm does not allow for safe train operation anymore, implying that the scenario 2a result in 2028 needs a line tamping action anyhow. This analysis also indicates that the short-term savings can only be achieved for a limited period of time. We show the long-term effects in applying the 4 tamping-algorithm. In both scenarios, the line tamping in 2018 provides a sound quality level, a SDLL of 0.61 mm in case of scenario 1 and of 0.825 mm for scenario 2. Looking at Figures 7 and 8, we can easily see that track quality deteriorated much faster in scenario 2, leading to shorter tamping intervals even though the intervention level is lower. Service life reaches 43 years (33.42 years forecasted by 4 tamping plus 10 years from 2008 to 2018) for scenario 2 and 49 years for scenario 1. Comparing ballast maintenance, ten line tamping actions are executed in both cases, so that the additional spot tamping of some 240 m between 2008 and 2018 in scenario 2 is the only difference. Scenario 1 ends up with 8210 m of line tamping equal to 164,200% for 49 years, scenario 2 needs 8700 m line tamping and the 240 m of spot tamping summing up to 198,000% for 43 years. Note: the costs of spot tamping that occur in both scenarios are not considered as they disappear in the comparison. Per year, the maintenance costs therefore amount to 33516 (scenario 1) and 4605% (scenario 2). It turns out that the short-term savings of 16.3% in the 10 year period turn into additional maintenance costs in the long run of 37.4% (average annual maintenance costs). The maintenance cost delta of 1254% per year for 43 years totals 53,906%. Compared to the short-term savings (18,400%) this means that every \"saved\" Euro in the short term is paid back with three Euros in the long term. Still, this is not the entire economic truth. As track service life is significantly shorter in scenario 2, additional extra costs occur: calculated depreciation (track re-investment costs divided by the service life) also increases for scenario 2 by 14%.