COST-effectiveness has always been crucial to operators of track construction and maintenance machines. However, all too often today operators are only looking for short-term savings so that, aside from the minimum technical requirements, only the acquisition costs are compared when acquiring a new machine. As a result, important factors such as the quality performed, annual output and annual operating costs are neglected.
Even though short-term savings are achieved, significant costs arise in the long-term that could easily be prevented. Every experienced railway engineer is aware that track construction and maintenance requires long-term thinking. Only by using machines properly can costs be reduced. So a long-term view is crucial to achieve maximum savings.
A calculation model has been developed to enable infrastructure managers to make a proper long-term assessment of the merits of different machines based on the following parameters:
- operation period: nine months, five days per week
- average duration of track possession: 120 minutes
- average number of track possessions per day: 1
- average length of work site: 2000m
- average distance to machine parking place: 10km, and
- approximate machine output: 60% of the maximum.
High-performance tamping machines are more expensive to purchase than lower-output machines, but one investment could save up to 66%, while annual cost savings of around 60% are possible. At first sight, these savings seem very attractive and often form the basis for acquiring new machines.
However, it is fair to ask whether it is possible to use high-performance tamping machines cost-efficiently for the long-term apart from the quality of the tamped track.
Tamping machine output has increased from 120m/h in 1955 to more than 2600m/h today, while work quality has improved. As a result it was possible to extend the intervals between tamping cycles from once a year to at least five years.
Track possessions are becoming shorter to minimise operational hindrance costs. This shows that not only is machine output critical, but also the time needed to transfer to the work site as well as the time required to set up and shut down the machine. Figure 1 compares the output of various machines.
Annual costs
The annual costs for an average work site length of 2000m and 2-hour track possession, range from 100% for an 09-3X tamper, to 74% for an 09-32 CSM, 55% for an 09-16 CAT, and 43% for an 08-16 SH. Figure 1 shows how both the high annual costs and the high cost per track possession incurred by the high-performance tamping machines stand out. However, when multiplying the cost incurred per track possession by the number of track possessions needed the savings potential is more than six-fold compared with lower-output tampers. This is due to the output of the machines: when 60% of the maximum output of every machine is used, low-output machines are much more expensive than high-performance machines.
Based on a required annual output of 517km, the annual costs incurred by all track tamping machines would double compared with the 09-3X (Figures 2 and 3). This, again, is due to the output with more low-output machines required to achieve the same output (Figure 4).
Looking at the actual costs incurred for a 2000m-long work site and a 120-minute track possession in detail, depreciation and interest as well as annual overhaul are the main cost factors. Compared with high-performance machines, machines with lower outputs require more staff which leads to higher costs.
Although high-performance machines require higher engine outputs they consume less fuel. As these machines work more efficiently, they need both less time and fewer entry and exit runs.
If the maximum output required is not needed or used, the high-performance machine is not always the most cost-effective option. The second fastest tamping machine, the 09-32 CSM, is the most cost-efficient option for a required output of 350km, followed by the fastest tamper, the 09-3X, and then other machines as several machines of these types are necessary to achieve the required output.
The higher the output of the machine, the faster a certain length of work site can be worked on during one possession. Therefore, high-performance machines are the more cost-efficient solution for short track possessions. Fewer track possessions result in a more cost-efficient work site.
Operational hindrance costs have not been taken into account for this example. However, when included, it is evident that high-performance machines are even more cost-efficient as they avoid the significant extra costs that additional track possessions would cause.
Moreover, in most cases, high-quality machines produce high-quality results. This leads to a higher initial quality of the tamped track and, when taking lifecycle costs (LCC) into consideration, results in an extended service life of the track, although this has not been part of this economic efficiency calculation either.
Not only is the machine's quality decisive but also its output. The latter can be judged by the annual maintenance costs. Machines manufactured to a high quality have lower maintenance costs. When serviced carefully, their service life is even extended, which in turn reduces annual depreciation and interest charges.
Another aspect is that longer possessions significantly reduce work site costs per metre of track. Depending on the machine, the cost reduction can amount to a threefold value.
It might appear that on/off-track machines are more cost-efficient than high-performance on-track machines since, in most cases, they can be parked relatively close to the work site. However, this is not the case, as on/off-track machines need a lot of time for set-up and shut down. Given the work site requirements defined in this example and regarding their working output, they work less cost-efficiently.
Today, environmental protection is of major importance, and attempts are being made to reduce CO2 emissions. Despite higher engine outputs, high-performance machines emit less CO2 than machines with lower outputs due to the smaller number of track possessions needed.
Despite the trend to relatively short track possessions, high-performance tamping machines definitely pay off when used for a realistic minimum output of 350km per year. Depending on the work site length, the most efficient machines need not necessarily be used. The right tamping machine meeting any requirement is available not only in terms of technology but also in terms of cost-efficiency.
Therefore, it is of utmost importance to compare the costs for both track possession and complete work site and to set these costs in relation to the annual output and the service life of the machine.
