Track Service Life Driven by Ballast Quality

Transcription

1 Graz University of Technology Institute of Railway Engineering and Transport Economy Track Service Life Driven by Ballast Quality Dipl.-Ing. Armin Berghold Paris, 6. December 2013 slide 1 TU Graz I Institute of Railway Engineering and Transport EconomyI DI Armin Berghold, Univ.-Prof. DI Dr. Peter Veit Paris, 6. December 2013

2 System Approach traffic load and volume alignment speed rail sleeper with USP ballast sub layer sub soil drainage Foto: Franz Piereder the whole track must be considered to evaluate one component, as the one component acts within the system slide 2

3 Technical and LCC Approach An integrative approach for track quality: A good track behaves well, a bad one deteriorates faster. The track deterioration depends on the current quality level. Differential equation: Q (t) Q = const. Q b t = Q 0 e Initial quality delivered by Investment Track deterioration fought by Maintenance slide 3

4 Source of Input Data Track Quality Behaviour In the following long term behaviour is discussed based on the e-function. slide 4

5 Investment re-investment Technical and LCC Approach Primary target is the support of LCC based strategies in demonstrating its economic benefits (including costs of operational hindrances) track quality track quality in -σ H initial quality maintenance economic life time critical track quality service life [a] the whole life span of track must be considered LifeCycleCosting cost consequences of track quality must be considered COH slide 5

6 Life Cycle Cost of Track Superstructure The aim of any track strategy is to reduce total costs of superstructure. Knowing the cost distribution (straight section, high loaded line) assumptions can be made: Depreciation is the dominating cost fraction (re-investment cost/service life) 50-80% up to 30% max 25% Costs of Operational Hindrances (COH) can be quite high Maintenance costs reach some 25% in maximum (in straight sections) All these cost proportions have interactions and therefore cannot be treaded separately! slide 6

7 decreasing track quality Renewal Track Quality Behaviour Time Intervention level slide 7

8 decreasing track quality Renewal Track Quality Behaviour Time Intervention level The better the initial quality the less the maintenance demand. slide 8

9 decreasing track quality Renewal Track Quality Behaviour Time Intervention level slide 9

10 decreasing track quality Renewal Track Quality Behaviour Time adequate maintenance fights causes Intervention level inadequate maintenance fights symptoms Just maintenance solving problems is sustainable. slide 10

11 decreasing track quality Reality in Track Looking homogeneous sections of one parameter set should result in the same track behaviour. time normal variation? Nothing special - just a drainage problem. Quelle: Diss. J. Holzfeind slide 11

12 quality figure Source of Input Data Technical Evaluation Measured data since ,800 km continuous track data including almost the whole main network of the Austrian Federal Railways Regression model based on MDZ-A value or standard deviation every 5 meters time track work Q(t) = Q n e b n t slide 12

13 Source of Input Data Behaviour of Track Section Investment Characteristics of the Standard Kilometre Service Life good subsoil conditions 400<R<600 double track Gross tons/day and track Rail Profile Sleeper Rail Steel E1 concrete R260 Life Span Relaying 1 Levelling-Lining-Tamping Spare Part Exchange 1 1 Rail Grinding Rail Exchange 0,3 Joint Maintenance Rail Pad Exchange Spot Repair 0,5 0,5 0,5 0,5 0,5 0,5 0, ,5 1,5 1,5 1,5 1,5 1,5 1,5 Planned Maintenance Small Maintenance (reactive) Calculating of all track work given in the working cycle including their costs of operational hindrances LIFE CYCLE COSTS slide 13

14 Source of Input Data Life Cycle Costing track section life cycle costs investment and maintenance strategy transport load sub soil sleeper profile steel grade R > 3000 m > gross/day, track good concrete 60E1 260 double track track work track laying $ 1 levelling-lining-tamping $ 1 $ 1 $ 1 $ 1 $ 1 1 $ $ 1 $ 1 $ 1 $ 1 grinding $ 1 $ 1 $ 1 $ 1 $ 1 rail exchange sleeper exchange exchange of rail pads joint maintenance small maintenance 0,5 $ 0,5 $ 0,5 $ 0,5 $ 0,5 $ 0,5 $ 0,5 $ 0,5 $ 0,5 $ 1,0 $ 1,0 $ 1,0 $ 1,0 $ 1,0 $ 1,0 $ 1,0 $ 1,0 $ 1,0 $ 1,5 $ 1,5 $ 1,5 $ 1,5 $ 1,5 $ 1,5 $ 1,5 $ 1,5 $ total costs Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ Σ dynamic costs evaluation principle (5% net rate of interest): minimum of dynamic average annual costs including costs of operational hindrances slide 14

15 Track Quality Behaviour Research Research: Analysis of b-rates under various boundary conditions Prognosis: From the past into the past from the past into the present from the present into the future The intervention level is stricter at the beginning! Due to ballast wear the b-rate rises. The tamping interval shrinks; at the end: more than one tamping a year. Slow order! Intervention level, deterioration rate and reachable quality (Q and b) show a stable correlation. Prognosis of track alignment and therefore also tamping demand is possible. slide 15

16 Track Quality Behaviour Research In this case: The ballast is the limiting element for the service life! slide 16

17 Cosequences of Ballast Wear Polluted ballast bed missing elasticity (breaking); inefficient drainage Vertical alignment failures single failures Concrete sleepers: Rail pads: high wear rail foot is pressed into the concrete, parts are chipped (rail inclination signal) Traffic load (flexing) and frequent tamping wear of sleeper edges (round edges stability) Wooden sleepers: Natural wear Rotting (transmission power) Pressed-in ribbed plates Shearing, Transmission power (gauge, rail inclination signal) slide 17

18 Example slide 18

19 Options to better the situation A working drainage system and a load bearing subsoil is assumed. There are at least two preventive possibilities to better the situation and extent service life and to prolongate maintenance demand: Increase ballast quality Use of basalt or granite and not weak limestone ballast Soft limestone compared to granite: Reduction of 20% track service life Reduction of 33% turnout service life Reduce forces in ballast Use of under sleeper pads slide 19

20 Investment Strategy Higher quality of materials Concrete sleepers with Under Sleeper Pads (USP) Getzner slide 20

21 Under Sleeper Pads contact areas sleeper - ballast after tamping 9% after tamping and stabilizing with Under Sleeper Pads (USP) up to 35% 3% to 5% after tamping before tamping up to max. 12% slide 21

22 Under Sleeper Pads reference track: 60E1 rails CW on concrete mono bloc sleepers 60E1 rails CW on concrete mono bloc sleepers with USP 1484 sections behaved like this But 16 did not? 12 section had no USP and 4 section showed very poor sub soil slide 22

23 Under Sleeper Pads Input Data due to 1500 Sections Actual Data Set Sleeper price + 30% initial quality increased by 18% proven b-rate reduced by 63% proven prolongation of tamping cycle by the factor of 2.75 proven prolongation of service life + 38% calculated (limited to maximum 50 years) All comments reflect a required internal rate of return of real 5%. Note: In general concrete sleepers are not in use at lines carrying less than 10,000 gross tons per day. slide 23

24 Basic Results Internal Rate of Return (IRR) for Under Sleeper Pads 25% Basic Evaluation (straight section) 20% 15% 10% 5% 0% Transport Volume [gross tons/day, track] Assuming a required internal rate of return of real 5% USP can be proposed independently from the transport volume. However, the higher the transport volume, the higher the benefits. slide 24

25 Basic Results Track Zusammensetzung der normalisierten Jahreskosten ung der normalisierten 140% Jahreskosten 140% of Normalized Average Annual Costs % 120% 100% 80% 60% 40% 113% 113% 100% 100% Average Gesamt Annual LCC Costs 120% Depreciation Abschreibung 120% Costs Betriebserschwerniskosten of Operational Hindrances Costs of Maintenance Instandhaltung 100% 68% 68% 68% Durchschnittliche Jahreskosten 80% 60% 40% 113% 100% 100% Zusammensetzung der normalisierten Jahresko Turnout EW 1200, Mn Herzstück starr, Bt/Tag, Betonschwe Gesamt LCC Abschreibung Betriebserschwerniskosten Instandhaltung 79-82% 82% 68% IRR up to 20% for high loaded sections 40% Ge Ab BE Ins 20% 20% 0% dauerverlängerung durch rlangsamfahrstellen ged Service Life due manent Slow Orders reference Minimalinstandhaltung Basis 2007 Minimized Maintenance 0% with Liegedauerverlängerung USP durch Schwellenbesohlung durch Prolonged Dauerlangsamfahrstellen Service Life due to Unders Sleeper Pads reference with USP Minimalinstandhaltung Basis 2007 Liegedauerverlängerung Schwellenbesohlung besohlt ohne zusätz durch Schwellenbesohlung Herzstück alle Auswertungen mittels statisc Rate of Interest = 0% slide 25

26 Variation of USP Cost Internal Rate of Return (IRR) for Under Sleeper Pads 25% 20% Basic Evaluation (straight section) USP: Sleeper Price +30% Variation USP: Sleeper Price +25% Variation USP: Sleeper Price +40% Variation USP: Sleeper Price +50% Variation USP: Sleeper Price +100% 15% 10% 5% 0% Transport Volume [gross tons/day, track] The economic efficiency increases with decreasing investment and increasing traffic load. However, the internal rate of return shows positive results in any case even independent form the traffic load. slide 26

27 Variation of Maintenance Demands and Service Lifes Internal Rate of Return (IRR) for Under Sleeper Pads 25% 20% Basic Evaluation (straight section) LLT x2,75; SL +38% Variation: LLT x2,00; SL +20% Variation: LLT x2,75;, SL +0% 15% 10% 5% 0% Transport Volume [gross tons/day, track] The evaluation shows that less technical effects on tamping (prolongation of tamping cycle by the factor 2 instead of 2.75) and the service life (prolongation of 20 per cent instead of 38 per cent) influences the results marginal. However, if service life could not be prolonged at all, USP can be proposed for lines carrying more than 12,000 gross tons per day, only. slide 27

28 Summary 25% 140% 120% 120% Internal Rate of Return (IRR) for Under Sleeper Pads 100% 100% Basic Evaluation (straight section) Zusammensetzung der normali Zusammensetzung der normalisierten 140% Jahreskosten Gesamt LCC 120% 120% Abschreibung 113% Betriebserschwerniskosten 100% 100% Instandhaltung 20% 15% 80% 60% 80% 60% 68% 10% 40% 40% 5% 20% 0% % Transport Volume [gross tons/day, track] Basis % 0% Liegedauerverlängerung durch Dauerlangsamfahrstellen Minimalinstandhaltung Basis 2007 Base Case without USP Liegedauerverlängerung USP durch Schwellenbesohlung durch Dauerlangsamfahrstellen Due to the basic evaluation every concrete sleeper should be equipped with USP, independently from the transport volume on the line. slide 28

29 Outlook Further researches in the next two years at the Institute of Railway Engineering and Transport Economy will be done: Laboratory test to measure the initial and long term settlement behaviour of five different ballast types using sleepers with and without under sleeper pads. Measuring the load distribution magnitudes under the ballast bed during the tests. Determining the material wear after the testing cycle. slide 29

30 Graz University of Technology Institute of Railway Engineering and Transport Economy Thank you for your attention! DI Armin Berghold slide 30

31 Back-Up slide 31

32 Under Sleeper Pads Track Zusammensetzung der normalisierten Jahreskosten of ung Normalized der normalisierten 140% Average Annual Jahreskosten Costs % Average Gesamt Annual LCC Costs 120% 120% Depreciation Abschreibung 113% 113% 100% 100% 100% 80% 60% 40% 140% 120% Costs Betriebserschwerniskosten of Operational Hindrances Costs of Maintenance Instandhaltung 100% 68% 68% 68% Durchschnittliche Jahreskosten 80% 60% 40% Zusammensetzung der normalisierten Jahresko Turnout EW 1200, Mn Herzstück starr, Bt/Tag, Betonschwe Gesamt LCC Abschreibung 113% Betriebserschwerniskosten 100% 100% Instandhaltung 79-82% 82% 68% 40% Ge Ab BE Ins 20% 20% 0% dauerverlängerung durch rlangsamfahrstellen ged Service Life due manent Slow Orders reference Minimalinstandhaltung Basis 2007 Minimized Maintenance 0% Liegedauerverlängerung with USP durch Schwellenbesohlung durch Prolonged Dauerlangsamfahrstellen Service Life due to Unders Sleeper Pads reference with USP Minimalinstandhaltung Basis 2007 Liegedauerverlängerung Schwellenbesohlung besohlt ohne zusätz durch Schwellenbesohlung Herzstück Rate of Interest = 0% additional investment in initial quality pays back alle Auswertungen mittels statisc slide 32

33 Quality Figure Δ Acceleration (MDZ) The quality figure MDZ describes the differences of accelerations in a fictive car caused by the geometry of track. The higher these differences the worse the riding quality. As failures in all directions (x-, y-, z) cause accelerations, the figure automatically sums up these influences by the physical laws. MDZ = v 0,65 1 * * L L 0 Diff. v 2 2 ( h ü) 2 impact of speed evaluation length impact of track geometry As this quality figure is speed dependent it allows calculating the acceptable speed possible for a certain real track quality. Moreover it allows comparing line quality with different speeds based on a given riding quality. slide 34

34 Total LCC Depreciation Cost of Operational Hindrances Maintenance Cost 100% 100% 90% 80% 80% 70% 60% 59% 50% 40% 30% 20% 10% 48% 42% 0% Trains per Day and Track slide 35

35 Total LCC Depreciation Cost of Operational Hindrances 160% Maintenance Cost 159% 140% 120% 123% 127% 100% 100% 80% 60% 40% 20% 0% Basic Strategy Permanent Slow Orders Minimized Maintenance Permanent Component Exchange Different Strategies (160 Trains per Day and Track) slide 36

36 decrease of track quality Technical and LCC Approach Calculation of e-functions for quality behaviour track work quality behaviour slide 37