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General information
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Description
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Open freight cars have a higher air resistance than covered ones. This is especially true for empty freight cars.
On services with a high share of empty cars, car covers could substantially reduce air resistance. |
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General criteria
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Status of development: research & experiments |
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(no details available) |
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Time horizon for broad application: 2 - 5 years |
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(no details available) |
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Expected technological development: basically exploited |
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(no details available) |
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Motivation:
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Energy saving |
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Benefits (other than environmental): small |
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Freight protection
In some cases the additional protection offered by covers could be an added
value to service quality. |
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Barriers: high |
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Freight handling
A major obstacle for covering freight cars will not be a technological one
but rather one of organisation, since such a measure will be difficult to adapt
to given operation patterns. The covers would complicate the loading and
unloading process.
Availability
A major challenge could be the storage of the covers when they are not
needed. For example a train transporting freight from A to B will not need any
covers on the way from A to B but will need them on the way back since the car
will be empty. A possible long-term solution could be flexible covers
permanently installed on the freight car. |
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Success factors:
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A convincing concept for the logistics and storage of the covers to ensure availability could eliminate organisational hurdles and scepticism. |
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Applicability for railway segments: low |
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Type of traction: electric - DC, electric - AC, diesel
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Type of transportation: freight
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This measure is only applicable to open freight cars. |
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Grade of diffusion into railway markets:
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Diffusion into relevant segment of fleet: (no data) |
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Share of newly purchased stock: (no data) |
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(no details available) |
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Market potential (railways): medium |
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(no details available) |
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Example:
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(no details available) |
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Environmental criteria
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Impacts on energy efficiency:
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Energy efficiency potential for single vehicle: > 10% |
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Energy efficiency potential throughout fleet: (no data) |
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It has been known for some time that open empty cars have a much higher air drag than full ones. In many cases this difference will be big enough to compensate the additional energy needed to transport the additional weight of full cars as compared to empty cars. Vollmer 1989 gives the aerodynamic values for a number freight cars including empty and full cars. Using the data for the freight car of type Eaos 106, one finds that full cars have 65% less air resistance than empty ones. - It is safe to assume that providing a cover for open freight cars will at least give the same aerodynamic advantage as filling the car since a cover will normally have a smoother surface than the load (e.g. gravel or coal).
- Therefore for trains consisting of open cars only (which is typical for long trains transporting mass goods such as coal etc.) the air resistance on the routes where the trains run empty would be cut by 65%.
- Since air drag accounts for about 50% of the total energy demand of a freight train and assuming that the additional weight of the cover is negligible for energy considerations, one gets an estimated saving potential of up to 30% - 35%.
- It is difficult to assess the relevance of empty open cars for freight operation in a general manner and their contribution to total energy consumption, because it varies strongly between different fleets.
As a conclusion, covering freight cars could cut air drag by one third in specific trains. An assessment of the overall potential in freight service is difficult. |
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Other environmental impacts: neutral |
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(no details available) |
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Economic criteria
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Vehicle - fix costs: low |
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Costs for cover are likely to be moderate. |
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Vehicle - running costs: significant reduction |
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(no details available) |
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Infrastructure - fix costs: (no data) |
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It is not clear whether additional infrastructure would be required for the storage and provision of the covers. This would not be the case for flexible covers permanently integrated into the freight car. |
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Infrastructure - running costs: increased |
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The provision of covers at the right spot at the right time would cause additional costs. This would not be the case for flexible covers permanently integrated into the freight car. |
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Scale effects: not applicable |
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(no details available) |
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Amortisation: (no data) |
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(no details available) |
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Application outside railway sector (this technology is railway specific)
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Overall rating
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Overall potential: promising |
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Time horizon: mid-term |
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From an energy point of view, covering empty freight cars is a highly promising measure. Since the covers will not be easily compatible with existing operational patterns, process complexity could be a critical barrier. The potential of the measure however justifies a more detailed assessment on possible lanes of implementation. |
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date created: 2002-10-17
