Capacity Increase through Optimised Timetabling

1
Capacity Increase through Optimised Timetabling

• Deregulation impact on timetabling
• Definition and variation of capacity
• Means of timetable optimisation
• A. Harmonisation of train speeds
• B. Estimation of capacity consumption
• C. Quality Management
• Mining, filtering and analysis of train
  detection data
• Stability analysis of network timetables
• Conclusions

AGRRI Network Capacity Seminar 28 November 2003
London
Ingo A. Hansen, Professor for Design of Transport
Facilities Faculty of Civil Engineering and
Geosciences Transportation and Planning
Dept. i.a.hansen_at_citg.tudelft.nl
2
Deregulation impact on timetabling

• Fragmentation of railway industry and capacity
  use
• Franchise contracts specified minimal train
  frequencies
• Lack of standard and know-how for timetable
  design
• application of running time supplements
• estimation of minimal headway times
• determination of time margins between train paths
• network impact of corridor and franchise area
  timetables
• train path assignment in case of conflicts

3
Definition and variation of capacity

• Route capacity Maximum traffic flow per track
  ( trains per day and peak hour
  respectively)
• Transport capacity Maximum transport volume per
  route ( passengers and tons respectively per
  time period)
• Capacity variation due to different
  characteristics of
• route infrastructure (alignment, single/double
  track, station spacing, power supply, signalling)
• rolling stock (weight, speed, length,
  acceleration)
• timetable (speed differential, frequency, time
  margins)

4
Capacity consumption according to Draft New UIC
Leaflet 505-1
5
Means of timetable optimisation

• Definition of optimality depends on targets
  e.g.
• throughput
• max. speed
• max. punctuality
• Determination of evaluation criteria and
  indicators e.g.
• occupancy (trains, tracks)
• delays (primary, consecutive)
• Modelling based on single-server queueing systems
  
• Measurement and assessment of impact (costs)
• Comparative and sensitivity analysis of options

6
Means of timetable optimisation

• A. Harmonisation of train speeds (Fleeting)
• dedicated lines for high-priority/high-frequency
  train services
• reduction of speed differential between lines on
  routes with mixed operation
• reduction of acceleration/deceleration time loss
  and dwell times by means of
• use of powerful electric multiple units (EMU)
• rolling stock with level boarding/alighting and
  wide doors
• automatic train departure/speed/dwell time
  supervision

7
Means of timetable optimisation

• B. Precise estimation of capacity consumption
• blocking time
• Definition Time needed by each train for
  running over a certain track section without
  hinder under prevailing speed and safety
  constraints (blocking time gt track occupation
  time!)
• running time margin
• depending on priority and occupancy of train
  service
• based on numerical calculations/empirical data
• time margin (buffer time) between blocking time
  stairway graphs

8
Estimation of blocking time
9
Blocking time stairway graphs

• minimal time headway depends on
• blocking times and speed differential
• between each pair of train paths
• critical track section where the time
• margin between the end of blocking
• time of the preceding train and the
• begin of blocking time of the following
• train is minimal
• route conflict where the scheduled
• blocking times of a sequence of trains
• overlap (theoretically) and leads in practice
• to bend of
• time/distance curve (deceleration) of
• hindered train
• increase of blocking times
• decrease of buffer times

10
Blocking time stairway graphs of double and
single track route
Source Draft New UIC Leaflet 505-1 Capacity
11
Blocking time stairway graphs of double and
single track route after compression
Source Draft New UIC Leaflet 505-1 Capacity
12
Relative timetable sensitivity
Differentiation of waiting time curve
Sources Hertel (1994), Pachl (2002)
13
Traffic energy
Product of number of trains and speed
Sources Hertel(1994), Pachl (2002)
14
Optimal capacity utilisation index
Source Hertel (1994), Pachl (2002)
15
Estimation of running time margins

• Different standards applied by each
  TOC/infrastructure manager ranging from 3 to 7
  supplement of the minimal running time in order
  to cope with minor delays
• Estimated running times applied by timetable
  designers are rounded-up and often historically
  infected
• Numerical calculation of minimal running times
  should
• be based on traction force/ speed diagram of type
  of rolling stock
• include alignment (grade) resistance and
  consistent train resistance function
• vary with weather condition and expected/recorded
  train load
• be verified by tests and measurements

16
Estimation of optimal buffer times

• Definition Time margin by which a train run may
  end later without pushing away a following
  (delayed) train
• Distinction between routes and timetables with
• variable headway times (mixed operation)
• constant headway times (dedicated high-frequency
  lines)
• Statistical analysis of operations performance
• recorded train speed (distribution)
• measured arrival and departure delay
  distributions
• realised headway and buffer times
• Modelling of realised capacity, recorded delays
  and evaluation of timetable options

17
Means of timetable optimisation

• C. Quality management
• (Historical) records of performance data
• failures of rolling stock and infrastructure
  (MTBF, MTTR, RAMS)
• primary delay statistics (routes, stations,
  lines, trains)
• caused by technical failures
• due to excess of running time/dwell time
• consecutive (knock-on) delay statistics (minutes
  per day)
• total delay (propagation, fading out time)
• reliability/availability/punctuality trends

18
Means of timetable optimisation

• C. Quality management (cont.)
• monitoring of operations performance per
  line/unit/ group indicating reasons and
  responsibilities
• development of improvement strategies/measures
• incentive for achieving a better level of service
• train drivers
• dispatchers
• timetable designers
• other staff

19
Conclusions

• Identification of critical network arrangements
  and train sequences
• Estimation of optimal buffer times between
  critical train paths at bottlenecks according to
  observed train speed and delay distributions
• Application of scheduled running times including
  effective margins and headway times between route
  conflict points in fractions of minutes
• Verification of impact of running time supplement
  and length of buffer time on punctuality/level of
  service
• Modelling of railway resources and operations as
  single-server queueing systems
• Determination of optimal capacity utilisation
  needs further research

20
Selected references

• Hansen, I. (2001), Improving railway punctuality
  by automatic piloting, In Proc. IEEE
  Intelligent Transportations Systems Conf. Aug.
  25-29, Oakland (CA), 792-797
• Yuan, J., Goverde, R.M.P., Hansen, I.A. (2002),
  Propagation of train delays in stations, In
  Allan, J., Hill, R.J., Brebbia, C.A., Sciutto,
  G., Sone, S. (eds.), Computers in Railways VIII,
  WIT Press Southampton, 975-984
• UIC (2003), Leaflet 405-1 Capacity, Final
  draft, March
• Hertel, G. (1994), Leistungsfähigkeit und
  Leistungsverhalten von Eisernbahnbetriebsanlagen
  (English Capacity and performance of railway
  operations facilities), In DVWG Schriftenreihe,
  B 178, Bergisch-Gladbach, 120-156
• Pachl, J. (2002) Railway Operation and Control,
  VTD Rail PublishingMountlake Terrace, USA, ISBN
  0-9719915-1-0
• Schwanhäußer, W. (1994), The status of German
  railway operations management in research and
  practice, Transp. Res.-A, Vol. 28A, No. 6,
  495-500
• Wendler, E. (2001), Quality management in the
  operation planning process by means of harmonized
  modelling, WCRR Cologne, 25-29 November, CD-ROM,
  paper no. 302