5. Strategy elements of railway infrastructure modernization
1.1 The effects of the increase of maximum speed and maximum admitted tonnage as a result of investments
In the following, the considerations will be focused on investment strategies in railway infrastructure through modernization works. Regarding the aim of investments, the infrastructure manager has to choose between two directions:
• The increase of the maximum traffic speed, specific to the high speed lines or passenger transport networks and operators;
• The increase of the maximum tonnage, a strategy dedicated to the networks with freight traffic superior to passenger traffic (for example, the railway networks in USA, Canada and Australia).
The concepts “increase of the maximum speed” and “tonnage” are related only to the direct effects of investments. Generally, through a modernization process that increases the value of the main parameters projected for the running track, superior values of maximum admitted speeds and tonnage are obtained. Their values vary according to the specificity of the activity and fundamental strategies.
The indirect effects of railway operation as a result of investments that aim to increase the maximum speed, maximum admitted tonnage respectively, are schematically presented in figures 25 and 26. The two situations are different, being specific to passenger, respectively freight transport networks. Regarding the railway networks dedicated to mixed traffic, the efficient option between the two directions of development through investments is difficult to choose.
No matter which option is adopted, the negative effects for the other area of activity are induced.
The excessive development of a railway network \primarily dedicated to passenger traffic (high speed and mobility) generates disadvantageous operational conditions for freight traffic. Firstly, tonnage and/or length limitations for trains are imposed. The lack of sorting units and technical stations with sufficient lines affects the level of mobility and connectivity of freight flows. The available maximum lengths of the delivery/dispatch lines of a passenger traffic network do not provide the possibility to operate freight trains of adequate length. Thus, the probability that this mode of freight transportation will become energy efficient is low. A similar situation, with difficulties registered in both directions (passengers and freight) is identified on the CFR network in the rehabilitated area of the pan-European Corridor IV.
In other train of thought, directing investments strictly to the freight railway transport, considering the existent mixed traffic, creates significant limitations for the passenger railway transport. In such a scenario speed restrictions and limitations are the main problems that could appear.
The value of work execution duration ( ) is influenced by the type of equipments and technologies used, the professional background/number of the personnel and the factors related to the amplitude of the structure, the category of the railway line (its importance and positioning within the railway network, the traffic, the maximum traffic speed etc.) and the geographic conditions. The cases when the railway traffic is totally suspended during the modernization\rehabilitation works on a specific section of a railway line are rare. Such a situation would be the most advantageous, because operations can be interrupted and will not be obstructed by the (minimum) traffic that must be maintained. Not all railway networks allow this. Often, practice has revealed that the bypass possibilities (without implying excessive extensions of the train routes – a fact that implies additional energy consumption, the increase of the transit time, significant cost increase etc) are insignificant. For this reason, the modernization\rehabilitation works are carried without the total interruption of railway traffic.
The aspects mentioned above determine prolongations (sometimes significant) of (Tr ) durations. Thus, works can extend on intervals ranging between a few days (in the case of easy works) and several years (in the case of complex rehabilitation works – for example: the rehabilitated sections of the pan-European Corridor IV Bucharest – Ploiesti and Bucharest – Constanta). Moreover, the timetables necessary for such works are influencing particular traffic conditions, such as: the occurrence of speed restrictions for the protection of the site areas, cancellations of trains, difficulties in railway traffic, the complete closure of a particular traffic section (in the case of double track lines), the adoption of temporary traffic systems etc. These disadvantages that cannot be avoided during work execution period are represented with dotted line in figures 24 and 25.
In other words, the beneficial effects of the modernization/rehabilitation of a railway line are observed after the complete fulfilment of related works, representing a “compensation period” (noted Tc in figures 24 and 25). In order to simplify figures 24 and 25 Tc is constant for all the indirect effects presented. In practice, the compensation time is different, its duration being determined similarly to case Tr. The main indirect effects related to infrastructure (running track) investments that aim to increase the maximum speed are the following (figure 24):
• The increase of the mobility level (M1->M2). This is the main advantage related to the increase of the maximum traffic speed. Decreases of the transit times occur, including transit periods that passenger trains register from the station in cause to the end station. A high level of mobility significantly attracts passengers towards the railway transport system. For the majority of individuals, the time concept has an important significance in the context of economic, social, industrial and cultural activities;
• The decrease of the transit times (T1->T2). This aspect is advantageous in the operation of passenger trains;
• The decrease of energy consumption (Co1->Co2). A running track that allows high speed operation without speed restrictions and limitations provides the conditions for an optimal and efficient exploitation regime for the traction equipments. In these conditions, the quantity of consumed energy corresponding to the number of carried passengers has low values. The resulted beneficial economic effects are significant;
• The environmental impact (I1->I2) decreases as a result of reduced energy consumption and silent running. The traffic of the trains with high and constant speeds reduces the powder resulted through repeated braking processes. The breaking processes make the high speed trains more environmentally friendly. Generally, the high speed trains use electromagnetic or electric breaking systems. Systems based on mechanical friction are used only in exceptional or emergency cases;
• The increase of passenger flow (F1->F2). It is a result of the increase of traffic speeds and mobility level;
• The increase of incomes (Î1->Î2). The increase of the passenger flow determines the increase of incomes.
There is a strong interconnectivity between all the aspects mentioned above. The variation (increase or decrease) of one aspect has influence on the others.
Figure 24. The indirect effects of railway infrastructure investment that increases the value of maximum admitted speed
For the investments that aim to increase the maximum tonnage, the indirect effects are the following (figure 25):
• The increase of freight volume (Vol1->Vol2). A high value of the maximum tonnage admitted on a certain network or section offers the possibility of using trains with greater length and higher freight volume. Moreover, the increase of the maximum axle load allows the increase of the effective load for freight wagons.
Remark: On the railway networks in North America, the mass of a four-axle railway vehicle can exceed 120 tonnes and the mass of a six-axle load vehicle can reach 180 tonnes. The economical advantages, from the point of view of the carried effective load, are vehement.
• The increase of energy consumption (Co1->Co2). At first analysis, this aspect can be considered a disadvantage. The increase of energy consumption is insignificant in comparison with the increase of the volume of freight. Against the road sector, in railway traction the values of energy consumption have not the same shares in report with carried tonne. In other words, if in the road traffic the aim is to double the freight traffic, the value of fuel consumption is also doubled at a certain moment. In the railway system, the doubling of the actual volume (by increasing the number of wagons or using heavy load wagons) does not lead to an increase of energy consumption in the same proportion, due to low mechanical resistance (significantly lower compared with a similar carried volume). Compared to other surface transport systems, the change of energy consumption is significantly lower related to freight volume variation;
• The increase of incomes (Î1->Î2) is related to the increase of freight volume. Longer and heavier freight trains generate increases of incomes;
• The increase of transport efficiency (E1->E2). The efficiency of the railway transport is a characteristic resulted by combining the variation of the other factors mentioned above. For example, the increase of efficiency occurs when a freight operator puts in operation very long trains (for example over 200 wagons – USA), or vehicles with high axle load (25 or 30 tonnes per axle). A highly efficient railway transport system is provided when the quantity of the consumed energy corresponding to each effective tonne carried is as low as possible. Moreover, the efficiency of this transport system is related to the optimal driving of the train.
Figure 25. The indirect effects of a railway infrastructure investment that increases the value of maximum admitted tonnage
2. The connection between the characteristics of the railway transport system and the economic development of certain states
The available statistics and the history of railway networks reveal that the economic and industrial development (for the majority of states) is strongly related to the extension and characteristics of these networks. The unprecedented industrial development registered in the 19th century was based mostly on the invention of the steam car – in fact, the steam locomotive. In comparison with road transportation, the ground transportation possibilities (economic and safe) of large freight volumes and a significant number of passengers offered by railway transport, have provided vast opportunities of rational distribution of industrial capacities as well as major implications in land planning. Often, large human settlements (and areas of industrial activity) have been created and developed as a result of the existence of railway transport facilities (railway hubs, connections with ports or areas of exploitation of main energy resources, etc).
The aspects mentioned above generally refer to the 19th century (the beginning of which marks the creation of the railway transport system). History after the “railway revolution” has proved that neither the 20th century has drifted from these international “trends”. The multiple advantages offered by the railway transport (especially military – important during that period) have determined the contemporary decision-makers to undertake ample policies for the development of railway networks. In fact, the major share of the total amount of kilometres of railway lines currently available to mankind was constructed in the 20th century. The fast evolution of the road transport system during the last 50 – 60 years has not led to the “eradication” of railway networks. The railway sector continued its strategic and economic role in the highly industrialized states, even after 23 years from the transition to the 21th century. The level of extension and development of the railway system in the highly industrialized states confirms this affirmation.
In order to confirm the aspects mentioned above, a comparison between the railway transport systems of several states from and outside the European Union is presented in the following. The analyzed states are: Japan, Russian Federation, United States of America, Argentina, Brazil, Germany, France, Great Britain, Italy, Sweden, Switzerland, Netherlands, Poland, Romania and Czech Republic. Their sequence is not based on aspects related to the development or importance, representing the order of their presentation in the sources. The main characteristics related to the railway transport system of these states (territory, the length of the railway network, the relation between the length of the network and territorial surface, the volume of carried freight, the number of carried passengers and the modal distribution in freight and passenger railway transport) are presented in table 1.
According to the data presented in table 1 it is observed that in addition to the direct proportional dependency between the territorial surface, the volume of carried freight, the number of passengers and the length of the railway network, the level of economic development has a significant influence on these characteristics. This aspect is revealed especially by the volume of transported freight and the modal distribution share (columns 6, 8 and 9 in table 1). Of all the 15 analysed states, it is known that the highest levels of economic and industrial development are in the United States, Japan, the Russian Federation, Brazil and Germany.
The parameters corresponding to columns 2,3,4,5,6,7,8 and 9 in table 1 are graphically represented in next figures .
The density of the railway network [km of railway line/km²] presents an atypical situation. It is observed that, of the analyzed states, the ones with a small territorial surface present the highest values (Czech Republic, Romania and Switzerland). Practically, the density of the railway network has a tendency of distribution inversely proportional to the territorial surface. Such a situation occurs as a result of two factors:
1. The scaling characteristics of the parameters in table 1 do not present connections on a proportional scale from a state to another. The differences between the extreme values (especially regarding the territorial surface) are significant. For example, in order to equalize Germany’s railway network density with the one of the United States it would be necessary to create a railway network measuring almost one million km – an aspect difficult to achieve from the economic perspective and considering the opportunities, even for the USA’s economic potential.
2. From the historic perspective, the construction and development of most of the current railway networks have been undertaken in the context of different configurations of the borders between the states, this issue corresponding to different administrative situations. Most of such administrative mutations took place in the 20th century. For example: the split of former Czechoslovakia, the disintegration of Austro-Hungarian Empire and Soviet Union etc.
The aspects presented above reveal that the economic development is compulsory connected to the existence of an appropriately maintained railway system and railway networks efficiently distributed on the territory.
3. Conclusions
The behaviour in time of the railway infrastructure is influenced by the level of stress generated by the traffic of trains. Any exceeding of the projected stress level causes significant accelerations of the wear-out process and the premature degradation of particular constituent elements.
The carried gross tonnage on a particular railway line can have different values defined through specific regulations and rules. This indicator is measured in hundreds of millions of gross tonnes (carried) and represents the quantity of cumulated tonnes (vertical load) carried on a particular running track section. Exceeding the designed length of trains or tonnage determines significant transversal or vertical efforts that accelerate the degradation and wear-out process. This creates possibilities for the occurrence of defects that generate speed restrictions or limitations.
The adoption of efficiently implemented investment strategies for railway infrastructure has significant positive effects on a medium and long term. The subsequent maintenance costs can be significantly reduced through higher values of the initial investments.
The lack of financing implies the adoption of compromise solutions, as introducing speed restrictions and limitations, closure of lines etc. All these aspects lead to the amplification of the negative consequences and losses caused by the decrease of the traffic, as well as the traffic capacity of the network. Finally, the efficiency of the railway transport system is affected in modal competition.
Figures
Marian CIOFALCĂ – Head of Service, Romanian Railway Safety Authority – ASFR ]
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