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Procedia - Social and Behavioral Sciences 48 (2012) 743 - 752

Transport Research Arena- Europe 2012

Changes of the infrastructure and operation parameters of a railway line and their impact to the track capacity and the volume of transported goods

Martin Kendra*, Matej Babin, Dalibor Barta

University ofZilina, Univerzitna 8215/1, Zilina 010 26, Slovakia

Abstract

The railway transport is considered as a one of the most environmentally friendly type of transport. With future prediction of increasing freight transport there are lines facing problems with demanded capacity. Increase of the track capacity could be achieved by infrastructure constructive adjustments. The contribution shows how the travel time can be minimized and the track capacity increased by changing some of the basic infrastructure and operation parameters, for example the minimal curve radius of the track, the number of tracks, or the usable track length at stations. Calculation of the necessary parameter changes is based on the fundamental physical laws applied to the train movement, and calculation of the occupation time is dependent on the changes of controlling the traffic between the stations.

© 2012 Published by Elsevier Ltd. Selection and/or peer review under responsibility of the Programme Committee of the T ransport Research Arena 2012

Keywords: track capacity; reconstruction; curve radius; speed; travel time; track mass capacity

Nomenclature

g gravitational acceleration [m.s~2] k number of trains in a group/bunch [trains]

I train passed distance [km] m mass [kg]

nmax maximum (theoretical) volume of the track capacity [trains]

* Corresponding author. Tel.: +421-41-513-3429; fax: +421-41-565-5816. E-mail address: martin.kendra@fpedas.uniza.sk.

1877-0428 © 2012 Published by Elsevier Ltd. Selection and/or peer review under responsibility of the Programme Committee of the Transport Research Arena 2012

doi:10.1016/j.sbspro.2012.06.1052

n1 "max maximum (theoretical) volume of the capacity on a i-section [trains]

T ^max resulted maximum (theoretical) volume of the capacity [trains]

p superelevation of the rail track [mm]

max rn Pt maximum normal superelevation of the curve rails [mm] theoretical superelevation of the rail track [mm]

r curve radius [m]

r mm minimal curve radius [m]

s gauge [mm]

^occ occupation time of the track rail per one train [min]

tt train travel time [min]

V train speed [m.s_1]

IA> IB subsequent meantime in the station A and B [min]

hoc length of the locomotive [m]

jf WU average length of a wagon unit [m]

rmax tr maximum train length [m]

Mloc mass of the locomotive [t]

M max maximum track mass capacity [t]

maximum permissible weight per the axle resulting from the track mass capacity class [t]

1^ goods maximum volume of the transported goods [t]

M™ ax maximum mass of the train [t]

M * lyl wu average mass of the wagon unit [t]

m<p! wu m goods average of the mass payload per wagon unit [t]

number of the axles of the locomotive [axles]

■\t max/ tr ^ axle maximum number of the axles in the train [axles]

■\t max/ tr ^ i,wu maximum number of wagon units in the train for the maximum number of the axles in the train, maximum mass of the train and maximum length of the train [wagon units]

■y max/ tr ^ wu maximum transported wagon units in one train [wagon units]

NT wu maximum transported wagon units - the section performance [wagon units]

p max maximum transport capacity [t.km]

T total calculation time - usually one day (1440 min.) [min]

Tad surcharge for the acceleration and deceleration of the train [min]

T ■ mm minimum train travel time [h]

T per time of period [min]

Ti ■ * mm minimum travel time in i-section [h]

total of minimum travel time of the train [h] Vmax maximum track speed limit [km.h1]

maximum admissible speed for the curve ride [km.h_1] ta , tb period of the traversing in the railway stations A and B [min] tab ,tba period of the subsequent drive in the railway stations A and B [min]

1. Introduction

The megatrend of the market globalization brings more and more requirements of transporting goods for the medium and long distances. Nowadays, the most of the goods is transported by the road. Its result is a major negative impact on the environment and a high value of external costs. This trend cannot be sustainable from the long-term point of view. The railway transport is considered as an environmentally friendly mode of the transport. Attempts are expected to move a large part of the freight transport from the road to the railway in the future. There can be problem with the railway lines that they don't have a sufficient track capacity. UIC-GTC report, created by the Kessel + Partner Transport Consultants and KombiConsult GmbH, expects many bottlenecks on the railway lines in the European countries by 2015, especially in the western area, as can be seen in Figure 1. It is necessary to look for the possibilities how to prevent the expected problems.

Fig. 1. Rate of railway line employment by 2015 (source: Study on Infrastructure Capacity Reserves for Combined Transport by 2015)

The tracks capacity can be increased by changing various types of the infrastructure parameters resulting from their modernization. The traffic capacity depends mainly on these two categories of parameters:

• track parameters,

• train parameters.

The basic track parameters are:

• number of the track lines,

• track speed limit,

• traffic signaling system,

• track leaning ratios,

• minimum curve radius,

• track resistance (slope, curvature, crossovers, tunnel).

The basic train parameters are:

load capacity (per axle, per usual loading meter),

maximum train weight,

maximum train length (in meters, in number of the axles), train driver (driving style, driver skills),

pull force of the locomotive engine (indicated, circumference of the drive wheels, at coupler, adhesion).

I ra iri length

Fig. 2. The traffic capacity dependence parameters

Based on the basic knowledge about the examined railway infrastructure, we can derive these two indicators:

• maximum volume of capacity (nmax ),

• maximum capacity of thetransportedwagon units pertrack section (NTWU ).

2. Dependence of the observed indicators on changes of the railway infrastructure parameters

Description of the main parameters, which are taken from the network chart edges analysis:

• minimal transport time ( Tmin):

o maximum of the track speed limit ( Fmax ), o minimum of the track curve radius ( rmin ),

• maximum capacity ( «max ):

o number of the track rails ( TR ), o minimum of the track curve radius ( rmm ), o maximum of the track speed limit ( Fmax )

• maximum capacity of the transported wagon units per track relay ( NTWU ):

o number of the track rails (TR),

o minimum of the track curve radius (rmm ),

o maximum of the track speed limit (Fmax),

o maximum track mass capacity (M max)

o maximum train length (L™ax ),

o maximum number of axles (N™^*),

o maximum train weight (M™ax).

The change of the clearance profile can increase the total volume of the transported goods. But the clearance profile is a very difficult measure for mathematical definitions. In this case we can consider it as the right measure the total number of transported wagon units. Then we just recalculate the total number of the transported wagon units to the transportation performance or the total volume of the transported goods.

3. Evaluating the minimal transport time

3.1. Dependence on the maximum trackspeed limit

If we simplify the train drive just to a drive with a fixed speed and zero acceleration, then the travel time is proportional to the train passed distance and inversely proportional to its maximum speed.

T ■ = —— (1)

mm v y

Than we can calculate the travel time for each track section and the total travel time on the passed track by adding the partial travel times.

3.2. Dependence on the minimum curve radius

In the curve ride with the radius r (m) by a fixed speed v (m.s_1), we must add also the centripetal force to the tractive force acting in the same direction as the curve tangent (Majercak et al. 2008). The centripetal force is directed into the curve center and it makes the trajectory curvature. Then the dimension of the centripetal force is:

p = [N] (3)

This force causes the vehicle response, which is equal to the size of the centripetal force but has the opposite direction - centrifugal force. This force is reflected at the railway vehicle on its wheel flange and gives the vehicle curvilinear movement. The centrifugal force and the vehicle weight together make the resultant into three typical aspects:

• resultant cuts the drive plane in the middle of rails - the equivalence is stabilized,

• resultant cuts the tangent point between the vehicle wheel and head of the rail - the equivalence is labile,

• resultant cuts the drive plane in general out of the rail track - the turnover of the vehicle:

o inside the curve - the track camber is abnormally high, o from the outside of the track - the camber is abnormally low. For the smooth curve ride and also the stabilized vehicle ride position we must eliminate the negatives of the centrifugal force effect:

sin a = —

The dimensions of the superelevation can be figured out of the resultant of the vehicle gravity and the centrifugal force which is perpendicular to the drive plane and axis of it. The pressure on the rails is the same.

The resultant R consists from centrifugal force P and the gravity force (G = m.g) which acts on the ride plane.

The angle a can be described also from the range of the liaison circles of the wheel set and the superelevation

sin a = —

.......V

■ lo

T ^ ^— -i- - * ■■ \ \

Fig. 3. The superelevation of the track in the curve (left: ideal situation; right: common situation)

Because the dimensions of angle a are too small, it can be written with the sufficient accuracy sina = tga and than

P = zL (V

from this situation, the superelevation is

pt = — gr

For the railway needs better suits the using of the superelevation in mm and the speed in km.h'1.

We can describe this superelevation as theoretical and we mark it pt. The theoretical superelevation is

used for the ideal situation - all the trains travel at the same speed. Generally the trains don't ride at the same speed, however, so this equation must be transformed (slower trains can damage the lower rail

in the curve superelevation). The transformation is made multiplying with —. This superelevation can be denoted as normal and sign it pn .

2 s.vz 2 3,6Z Pn =~

2.s.V z

3 g.r 3 9,81 .r 381,41 .r

The superelevation of the curve rails can be stated by each country on its own decision. That's why we can count the maximum speed in the curve ride in the general conditions

2.s.V i

381,41 ,rm

J38M1.W P„ = 13;8Li

The next calculation will be made by (1).

4. Evaluating the maximum capacity volume

Maximum (theoretical) volume of the capacity is proportional to the calculated time and inversely proportional to the occupation time of the track per one train.

7 (11)

n'» = ^

The resulting track volume capacity is given by the volume of the capacity of the constraining section (it is the section with the lowest capacity)

m = minli' „! (12)

5. Calculation of the occupation time tocc

5.1. Single track, simple, matched train diagram RST A

Fig. 4. Single track line, simple, matched train diagram

, _ Tper _ 2.t, +TA +TB + Tad

occ 2 2

= 60.rmi„ = -

The next calculation will be made by (11). 5.2. Single track, grouped, matched train diagram

_ Tper _ 2.k.t, + (k -1 ).(tab +tba ) + ta + tb + Tal

«cc 2.k

= 60.rm

The next calculation will be made by (11).

tt TA tt TAB tt TBA tt

4- r-rGROUP 1 PI lR _^

Fig. 5. Single track, grouped, matched train diagram

5.3. Single track, bunched, matched train diagram

RST A _

IB IB tt TA tt IA IA Tb

UN PER -fe.

Fig. 6. Single track, bunched, matched train diagram

1 per 2.k

t, = 60Jm

. = Tpe^ = 21, + (k -\).(JA + IB ) + ZA +ZB + Tad locc 2.k

The next calculation will be made by (11).

5.4. Double tracktrain diagram

= 2-T = AT

- IA + IB - Ia + IB 2

(20) (21)

The next calculation will be made by (12).

<-► 4-►

Fig. 7. Double track train diagram

6. Evaluating the maximum transported wagon units - the section performance

The basic calculation of the section performance is:

NT = nT Nmaxl tr

wu "maxv wu

7. Calculating the maximum volume of the wagon units in one train

The maximum number of wagon units can be limited by:

• the maximum number of the axles in the train,

• the maximum mass capacity of the train,

• the maximum length of the train.

7.1. Maximum number of the axles in the train

In general double axles wagon is one wagon unit, one bogie wagon (with four axles) are two wagon

*jmax/tr _ *tIoc max/ tr _ ^ axle ^ axle

7.2. Limit of the maximum mass capacity ofthe train

* axle

(A-16,0t/axle; B - 18,0 t/axle; C-20,0t/axle; D - 22,5 t/axle) 7.3. Limit ofthe maximum length ofthe train

max/ tr _ ^ tr loc '

The final maximum number of the wagon units in the train is set by the minimal value of the maximum number of the wagon units which depends on:

• maximum number of the axle in the train,

• maximum mass of the train,

• maximum length of the train, "nte*} (26)

The next calculation will be made by (22).

8. Calculating the maximum value of the transported goods and the transportation capacity

For calculation of the maximum value of the transported goods and the transportation capacity we can use calculation of the maximum value of the transported wagon units - performance section. For the calculation we need:

• average used mass per the wagon unit,

• length of the section.

ft* ™ (27)

(rnnnx v x

0.00% 20,00% 40.00« 60,00» 80.00% 100.00% 120.00% 140,00% The change of the chosen infrastructure parameters in %

Fig. 8. The example of the dependency between the transport capacity and the chosen infrastructure parameters on the chosen 15 km long track section

9. Conclusion

In this century the sustainable transport can be further developed only with the continued support and preference of the environmentally friendly transportation. The railway transport is the transport with relatively low negative external costs to the environment. To remain competitive it must offer quality services with a sufficient capacity. Some railway corridors in Western Europe are not able to offer the required capacity because of the increased demand for the transport. Modernization of the railway lines can change their parameters and increase their performance.

Changes could be made in the infrastructure and operation parameters. In this contribution calculations of the track capacity and the volume of the transported goods are suggested, depending on the minimum radius of curvature changes, the transport organization between stations and train parameters depending on the characteristics of the line. Calculations showed that the same percentage change in the input parameters of the track, train and operation brings a different magnitude of increased traffic capacity. At the same time, the maximum increase of the traffic capacity is bounded above and can not be continuously increased without changing other parameters.

References

Gasparik, J., Peceny, Z.: (2009). Grafikon vlakovej dopravy a priepustnosf sieti, EDIS, Zilina, ISBN 978-80-8070994-5, (Chapter 5)

Majercak, J., Gasparik, J., Kendra, M., Majercak, P., Blaho, P. (2008). Zeleznicna dopravna prevadzka Technologia zeleznicnych stanic, EDIS, Zilina, ISBN 978-80-8070-887-0, (Chapter 2)

Study On Infrastructure Capacity Reserves For Combined Transport By 2015 prepared for International Union of Railways Combined Transport Group (UIC-GTC), Kessel + Partner Transport Consultants, KombiConsult GmbH, Freiburg/Frankfurt am Main/Paris (2004)