Integrated System Planning (ISP) is a multi-step hierarchical process as shown in Figure 1 comprising

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1 Integrated system planning for railways J. Dreier, U. Brockmann IWIngenieurgesellschaftfur Verkehrsplanung und Verkehrssicherung GmbH, Obergstrasse 5, D Braunschweig, Germany Abstract Integrated System Planning (ISP) is a method for optimizing long-term assignment of railway passenger carrying capacity to passenger demand. The three goals of ISP are (1) to increase the market share of railway passenger transportation (strategic area), (2) to balance passenger load on trains by coordinating regional and long-distance traffic to arrive at optimized timetables (capacity area) and (3) to lower production cost by integrating production planning to optimize rolling stock and personnel assignment (resource area). ISP and railway operations are supported by compatible software packages that eliminate manual data reentry. 1 Introduction Integrated System Planning (ISP) is a multi-step hierarchical process as shown in Figure 1 comprising Passenger Demand Determination Supply Planning (Timetable Generation) Production Planning Final Planning Public Transport Process A unified data model enables seamless integration of all parts of ISP. ISP's applicability to freight transportation is limited because freight trains are frequently dispatched on demand rather than according to a timetable. Therefore we limit our discussion to passenger transportation.

2 156 Computers in Railways At IVV we have developed software packages that interactively support supply planning and production planning. These software packages have been deployed successfully at the national rail companies of Germany (Deutsche Bahn AG, DB AG), Switzerland (Schweizerische Bundesbahn, SBB) and the Netherlands (Nederlandse Spoorwegen, NS). Timetables are generated in several stages with mathematical optimization methods. At each stage the results of different planning strategies can be compared. 2 Passenger Demand Data ISP is based on passenger demand data commonly supplied in form of a sourcedestination matrix derived from forecasts or passenger counts. A sourcedestination matrix consists of the number of passengers who want to travel from a railway station A (source) to a railway station B (destination) for all possible combinations of A and B. Line-based passenger demand data is not used because it is unsuitable for line planning. The German federal government regularily compiles passenger demand data covering approximately 1000 German railway stations while preparing the "Bundesverkehrswegeplan" document. Passenger demand data is listed separately for different travel purposes such as commuting and leisure time travel. 3 Supply Planning (Timetable Generation) 3.1 Network Structure Planning Based on passenger demand, supply planners determine which railway stations will be stops for which types of trains. As shown in Figure 2 the resulting network structure influences modal split, the distribution of passengers across the competing automobile, air and rail transport systems, and determines system split, the distribution of passengers across the different types of trains. The German national rail company, Deutsche Bahn AG, distinguishes InterCity, InterRegio, Regional Train and Regional Express train types. Network structure planning determines trip lengths between neighboring stops (running time tables), source-destination matrices and the number of travellers between neighboring stops (edge loads) for all train types. 3.2 Line Planning Since its inception at the end of the 19th century urban public transport has been based on organizing vehicles into "lines" that run the same routes frequently at regular intervals. Public railway transport, traditionally based on infrequent or irregular service, introduced line-based service much later. For

3 Computers in Railways 157 example DB AG did not offer line-based service until the introduction of the InterCity-system in For each line line planning determines the beginning and ending railway stations, the routes and stops and the frequency of runs. IVV's software package PROLOP supports interactive line planning. It evaluates the resulting line networks through load simulation without requiring prior line alignment. Data sets can be but do not have to be timetable-based (line-based). PROLOP's load simulation component uses a sophisticated proprietary graph algorithm to calculate all routes travellers may reasonably choose from any railway station (source) to any other railway station (destination). It then calculates traveller streams based on passenger demand. The output typically includes the passenger loads for all lines and route sections, the transfer flows at all interchanges, the quality of service provided to each railway station and profitability data including expense and revenue kilometers and total waiting time. Profits or losses generated by each line can be calculated. PROLOP can also use line optimization to automatically generate a line network in which the number of times that travellers have to change trains is minimized. Usually an automatically generated line network defines a basic set of passenger service that is used as a starting point for interactive expansion. 3.3 Planning Alignment of Lines Line Alignment Each line is assigned either an arrival time or a departure time at one designated railway station as a handle. For each line the arrival and departure times at all stops can then be calculated for all trips by adding (subtracting) the lengths of trips and stops and multiples of the line interval to (from) the handle. While line planning strives to minimize the number of times travellers have to change trains, line alignment strives to minimize waiting times at interchanges for those travellers who do have to change trains. Lines can be aligned either

4 158 Computers in Railways by adjusting the handle or by increasing the stop length at an interchange to wait for another line. Through iterative line alignment and load simulation, synchronization of lines with large transfer flows can be favored over synchronization of lines with small transfer flows. To support this optimization, PROLOP realistically simulates traveller behaviour by reacting sensitively to line alignment Conflict Checks The following operational restrictions are checked in this planning step: adherence to minimum stop lengths to ensure safe boarding and alighting, adherence to technical minimum trip lengths between network vertices, observation of minimum safe distances between trains (generally based on gantry equipment and block lengths), interdiction of oppositely headed trains on single tracks and interdiction of train crossings at entry areas of railway stations and branch points Optimization For automatic optimization the line alignment problem is transformed into a linear problem that can be solved with standard software for linear optimization. The transformation is based on public transport and operational restrictions that represent timetable internals and ensure that the optimized timetable is free of conflicts. The goal function of the optimization is derived from customer needs. 4 Production Planning 4.1 Train Planning After line alignment changes can be made to individual train runs to account for local and time-of-day conditions. For example additional trains with slightly different routes could be scheduled during rush hour for the duration of the planning period. Additionally standard train configurations are chosen for each train run. Choices include the number of coaches for each class and on-board services.

5 Computers in Railways 159 The resulting individual train runs form the basis for personnel and rolling stock allocation. 4.2 Personnel and Rolling Stock Allocation The allocation of personnel (including motor unit drivers, conveyers, carriage and wagon examiners) and rolling stock (including coaches, motor units, motor train units) which links supply planning and final planning/the public transport process is divided into three periods: long-term allocation, primarily for strategic analysis of capacity, for example in connection with strategic line planning as part of supply planning, medium-term allocation of rolling stock to all regular runs of a timetable period and short-term allocation of rolling stock and personnel to special runs as needed. While both coaches and motor units have to be allocated for runs involving trailing stock, only motor train units have to be allocated for runs of motor train units. At IVV we have developed several software packages for personnel and rolling stock allocation that our customers have deployed successfully: Software Package PRO-DIGEST Traction- Allocation-Planner TAP PROWUD covering motor units motor unit drivers conveyers motor units motor unit drivers carriage and wagon examiners shunters cleaning staff Customer SBB Deutsche Bahn AG

6 160 Computers in Railways PRO-DIGEST PRO-DIGEST is an interactive graphical software package for medium-term allocation of motor units and train crews at the Swiss national rail company (SBB). All regional offices of SBB, Zurich, Bern and Lausanne, have used it successfully and productively since PRO-DIGEST reads the timetable data generated by SYFA, a software package used by SBB for supply planning. PRO-DIGEST comprises a component for motor unit tour planning, a duty roster generator for motor unit drivers and a duty roster generator for convoyers. Motor Unit Tour Planning A motor unit tour may last many days and might for example consist of taking some trailing stock from A to B, running empty from B to C, doing some shunting jobs at C and subsequently pulling the same train back and forth between C and D a couple of times before finally returning from C to A with a few coaches. Tour planners use PRO-DIGEST to interactively and graphically combine runs generated by the supply planning software into tours for all types of motor units. PRO-DIGEST supports this process by automatically finding successor and predecessor runs that can be linked into the current tour. Instead of forcing planners to start from scratch every time, PRO-DIGEST reuses previously generated tours as much as possible. This allows SBB to run PRO-DIGEST on updated supply data every week. The tour planner also analyses stoppages, checks for completeness and guarantees observation of minimal reversing times based on location and motor unit type. Additional runs, not generated in supply planning, such as shunting runs, empty runs, local services and the use of multiple motor units per train can also be entered. Duty Roster Generation for Motor Unit Drivers To ensure inclusion of additional runs, the duty roster generator reads all runs known to the tour planning component rather than only those written by SYFA. Motor unit drivers are grouped by their qualifications. A shift is a sequence of runs that can be executed by one driver in one day. PRO-DIGEST supports interactive graphical shift generation by automatically finding successor and predecessor runs for inclusion in the current shift. After all shifts for a driver group have been generated, shifts are linked together to form shift sequences

7 Computers in Railways 161 with a common length of one week. Finally all shift sequences are assigned to individual drivers to form a duty roster for the driver group. The duty roster generator reuses as much of its last output as possible to prevent operators from having to start from scratch when new runs are read from the tour planning component. PRO-DIGEST checks that all runs have been assigned to shifts, guarantees that enough time is allocated for driver transitions and for preparation and shutdown of motor units and calculates minutes worked per shift. Additional driver duties such as guest runs and preparation and shutdown times can also be entered. Duty Roster Generation for Convoyers Duty rosters for convoyers are generated with the same general method as duty rosters for motor unit drivers. PRO-DIGEST accounts for seasonal differences in work load due to holidays and tourism and provides additional functions including scheduling of passenger counts and intensified ticket controls. The introduction of PRO-DIGEST allowed SBB to compare the results of several alternative planning strategies during a limited planning period for the first time Traction-Allocation-Planner - TAP (Deutsche Bahn AG) Traction-Allocation-Planner (TAP) is the graphical interactive software package for use by the traction division of the German national rail company (Deutsche Bahn AG) for allocation of motor units and drivers to regular and special train runs. IVV has completed detail analysis and design of TAP and is currently implementing the software package which is scheduled for release in the first half of TAP accepts requests for tractive services for both regular and special runs and services them by economically allocating tractive stock and drivers. TAP comprises four main components, order entry, motor unit allocation, motor unit driver allocation and base data and system functions as shown in Figure 3. TAP distinguishes between regular and special runs based on regularity and frequency. Tractive services for most regular runs and a minority of special runs are allocated by DB AG's central office. Tractive services for most special runs and those regular runs, for which tractive services cannot economically be allocated at the central office, are allocated at the appropriate regional office. Almost every run is assigned a public transport day key that determines on which days of the year it occurs. "All mondays", "Mo-Fr", "Sa and Su except holidays" and "May 1" are all valid values for public transport day keys.

8 162 Computers in Railways Order Entry TAP accepts orders for tractive services in accordance with procedures that the traction division of DB AG and its clients have contractually agreed on. Motor Unit Tour Planning TAP includes both a "regular" and a "special" module for generation of motor unit tours. In a first step the regular module is used to combine regular runs into "regular" motor unit tours. In a second step the special module is used in an attempt to add special runs to the regular tours by modifying regular tours only for selected public transport day keys. Where this fails TAP generates "special" motor unit tours associated with special public transport day keys. Motor unit allocation with TAP features selection of runs graphical public transport day key-oriented tour generation graphical day-of-week-oriented tour generation automatic search function for successor and predecessor runs entry of empty runs and run-along non-tractive motor units calculation of minimum reversing times stoppage statistics dynamic incorporation of updated requests for tractive stock completeness checks for unallocated runs hardcopy of tour diagrams statistical analysis TAP provides a graphical user interface featuring block diagrams as shown in Figure 4, for both motor unit driver shift generation (described below) and motor unit tour generation. Shift Generation for Motor Unit Drivers Shift generation, similarily to motor unit tour planning, produces regular shifts from regular runs, adds special runs to regular shifts and creates special shifts where necessary. TAP hands the resulting shifts and other final planning data directly to the TEF final planning software package. TAP's shift generator features include selection of runs graphical public transport day key-oriented shift generation graphical day-of-week-oriented shift generation automatic search functions for successor and predecessor runs guest run entry calculation of preparation and shutdown times calculation of transition times calculation of work, duty and break lengths check for compliance with hour regulations

9 Computers in Railways 163 dynamic incorporation of updated requests for tractive services completeness check for unallocated runs hardcopy of shift diagrams statistical analysis PROWUD (Deutsche Bahn AG) In between runs trains have to be serviced by carriage and wagon examiners, who ensure safety and readiness of trailing stock, and by cleaning staff and shunting gangs. The time allocated to examinations of carriages and wagons differs with type and is determined by DB AG regulations. Planned stoppages usually last longer than examinations thus creating an opportunity for optimization of personnel allocation. The PROWUD software package has replaced manual duty roster generation for carriage and wagon examiners. PROWUD relieves planners of repetitive analyses and calculations with interactive work, decision and planning aids. It provides a convenient graphical user interface for input of base data such as trip lengths and cost centres and represents data in a clear table format. PROWUD automatically calculates job lengths based on carriage type or number of wheel sets per wagon. The planner uses the graphical user interface to easily and efficiently create, modify and print duty rosters as shown in Figure 5. While the lengths of examinations are fixed, their relative positions within the corresponding stoppages can be chosen by the planner. After interactively entering the current values for optimization criteria (hour and break regulations) he choses the optimization function to generate particularly efficient duty rosters. Interfaces to the centralized IFB and PSP databases reduce the need for manual entry of train and tour data as much as possible.

10 164 Computers in Railways Figure 1: Hierarchical Organization of the ISP Process

11 Computers in Railways 165 Figure 2: Supply Definition and Network Structure Planning

12 166 Computers in Railways Traction Allocation Planner Order Entry Representation of the Order Entry Process Resource Allocation - Quotation Generation - Run Generation Tractive Stock and Personnel Allocation Motor Unit Motor Unit -coarse Driver Allocation - medium grain Allocation -fine grain grain - run entry j! J -tour generation ^( Target Data Price List Partial Tours Tours Figure 3: Traction Allocation Planner for Deutsche Bahn AG: Functional Overview

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