Automation for Bus Operation in Paris

AUTOMATION FOR BUS OPERATION IN PARIS

Jean~aul PERRIN Direction des services techniques. Paris transport authority (R A T P)

ABSTRACT For several years the Paris transport authority (R A T P) has been automatizing operations aimin g to adapt bus traffic to demand or to improve hus control. The various aspects which can he pointed out are - data collection on bus running and passenger fl ow, - assi gnment of buses and es tab lishmen t of hus scheduling and crew duty rosters, - real-time tracking of bus movement and its pe rturb ations , - traffic control, - passenger control and information. The aim of this paper is to make a survey o~ the different devices or processes which are under study, under experimentation or in operational use by RAT P, and to sum up what lessons can he learned and what bene fits have been obtained or are expected. As far as possible, the results and progress of the projects or of evaluations in process are given. The great number of routes of the Paris network and the diversity in traffic conditions make possible different solutions depending on the characteristic features. A global picture of the different means should lead to the definition of a certain policy in their use which depends upon their efficiency with respect to their cost. Automation is heeing implemented, step by step, as fast as principles. are stated and experimental results are ohtained.

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AUTOMATION FOR BUS OPERATION IN PARIS

Jean-Paul PERRIN Direction des services techniques Paris transport authority (R A T P)

1 - Introduction

The use of automatic devices releases the staff from repetitive jobs and supplies precise information through more complete and rigourous computer processing.

With its 1 BOO km of routes and 3 700 vehicles, the Paris transport authority bus system is faced with numerous problems depending upon the type of service and the region of the Paris area served. Several years of research have been devoted investigating into automation and the use of computers and of radiotransmission, means in order to help or to manage bus operations.

Aside from the question of cost, the fundamental problem to be solved concerns the quality of the information obtained. Several test have been attempted to see ~hat precision" could be excepted from the de vice counting the number of revolutions of th! wheels depending on the state of the tyres, grocnd adhesion, variations in running, ..• and from passenger load counting (a double barrage of electric photocells has been retained).

We propose, here, without going into great tech~ nical details, a quick survey of different devices or processes used"or envisaged, and an account of what has been learned and what benefi t has resulted or is excepted from this work. We shall try to draw some conclusions about the applications of our findings which will be adaptable when all the sub-systems have been evaluated from a technical as well an operational point of view:

this basis and after preliminary experiments, the realization of prototypes using microprocessing techniques and cassettes recording started in 1975 in view of preparing equipment of several dozen buses to be put in service for counting campaigns. At the beginning of such campaigns (generally one week long) a conveniently identifiable cassette will be inserted into the device and will automatically record the data. On

The different aspects are : - data collection on bus running and passenger flow, assignment of buses and establishment of bus scheduling and duty rosters, - real time tracking of bus movement and its perturbations, - traffic control, - passenger control and information. 2 - Operational data To establish a service which is coherent with transportation demands and environmental constraints requires a good knowledge of arrivals at stations, origins and destination of passengers, and travel times. This information can, for the most part~ be perceived from the characteristics of running buses, and the number of passengers who get on and off; series of measures, more or less frequent, are sufficient to follow the evolution of parameters and to proceed to an adaptation of service.

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A small computer preprocess data before ft lrther statistical computer processing. In order to implement processing under good conditionE, it is necessary to obtain good fiability of recorded data by each apparatus. Special care must be taken in installing equipment which shoulc" be as automatic as possible so that its operaticn does'nt overburden crews, and manipulation errors are kept down to a minimum. Since breakdown alarm is provided and, at the pretreatment, coherence improvement is made, it is possible to replace the apparatus during the campaign or to eliminate erroneous information. However, unautomated counting and inquiries remain necessary in order to understand origin-destination assesments and waiting times.

3 - Adjustment of operations with respect to demand

- emergency contact in case of security imperatives (this application fortunately without real need in Paris as yet, was the reason for many telephone connections between vehicles and central control in other networks).

Once data has been collected, and at the present time this is done without automation, it must be used to adjust operations (a first step which will only be mentionned here concerns the network's structure the study of which is the first link in the chain we are now describing).

The parisian operating staff has retained two principles for the system's organization - selective call for each route,

The different stages of this adjustment are: setting up a schedule for a given service quality, "dressing" the schedule in terms of crew para-· meters, establishing crew rotation. In practice this results in a work sheet which details crew and bus assignment.

- control center in points instead of routes keeping un to the end of the

one of the line's terminal a single center for all personal contact through route.

Fixed emission-reception installations (16 channels actually in service and more that 30 when the project will be completed in 1977) are however grouped on the last but one floor on the Montnarnasse Tower which dominates the Paris area from its 200 meter height.

At first glance, the much praised power of computerized methods could bring a simple answer to such prob lems, but the combinational analysis involved is so intricate that several studies have been necessary and numerous algorithms tried before any satisfactory solution appeared.

The richness of information from personal conversation is useful in exceptional cases, but can be redundant for such systematic data as bus position on the line; this has brought about the idea of trusting this task to an automatic system.

We shall no develop here these questions which belong to operational research and habe been the subject of many publications ((2), (4), (5), (6)), but we feel necessary to insist upon the fact that the problem is very complicated and that results can now be obtained; the operational appreciation will depend solely upon convenient data collection once the structures are set UD.

The degree of sophistication necessary for such a system and its justification are not as evident as some may think. This is why the RAT P made a study of an exPerimental automatic control system of bus movement (SECAMA) which supervises a 35 vehicle line (route number 52 Opera - Pont de Saint-Cloud). Conceived in 1972-1973, the SECAMA has been technically operational since the beginning of 1975. The technical evaluation was therefore almost finished by the end of 1975.

4 - Real time tracking of bus movement and its nerturb ations In order to have a bus line running satisfactorily, traffic blocks and breakdowns must be knmvn within a determined time delay. Their nature is such that they may cause irregularities which annoy passengers wa~t~ng at stops. This knowledge can be gained in different ways : continuous or spot checking (sampled in time or distance). Terminal point situations, traffic vehicle observations, drivers" reports of acci dents or breakdowns were original traffic information sources. It was thought that some improvement could be achieved by automatic beacon devices installed at critical route points, but cost and maintenance made this idea hardly workable and in 1969, four bus lines were equipped with radiotelephones so t~at drivers could· be in permanent contact with control centers. The results of this experiment were as exPected, and the decision has bee, made to have the entire bus system equipped with them by 1977.

In order to value different aspects, the system permi ts : - the receiving of data by cyclic interrogation of buses (10 second cycle for the 35 buses equipned) concerning : their position, the nlmDer of passengers getting off and on, and to have visual disnlay of these facts, - to transmit certain orders of information by visual display to drivers, - to control telephone connections and even address messages directly from the center by internal or external sonorization of the vehicles,

There are many advantages to this system data recording in order to edit statistics (a collection of date which does not necessarily need, as stated above, real time).

- immediate transmission of incidents or accidents without need for the driver, alone in the bus, to leave his vehicle,

Finally a certain regulation level is foreseeable as it will be later exPlained.

- information at request as to bus positions along the line,

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5 - Traffic regulation

Knowledge of bus location and subsequently knowledge of what extent the buses are early or late versus a reference shedule, led us to support automatic route regulation. But the inherent difficulties will not in most cases bring out noticeable benefi ts for the passengers.

From the knowledge obtained by different means of following buses in operation, it is possible to consider a corrective action at terminal points or at several points on the route in a more or less continuous way. This action is simplified if buses have their own track (such as a reserved lane) or can impose their movement despite traffic (priority at traffic lights).

SECA~A

has been technically working since early 1975. The first ooeration consisted of a technical evaluation of its components quality of date transmission, localization accuracy, cycles deviations, reliability, ... ) in order to define the best solution to be retained for an operational sys tern.

It must be remembered that controlling a bus route in a mainly banalized environment leads to very complicated problems in which the human asoect must be highly considered: chronological constraints are caused by links between rosters and the many drivers' appointments they imply.

The ooerational evaluation be gi nning late 1975 should permit a comparison between the effects on bus traffic and oasqengers satisfaction provided by the different means. The results obtained are ye t to be checked, as to ,.hether they are a general meaning or whether they are restricted to the particular case of route 52.

Terminal departure regulation has been realized for a certain number of lines by means of devices envisaged more than 25 years ago, using punched film the speed of which can be modified by the line superintendent in relation to specific ci rcums tances •

In collaboration with traffic authorities, RAT P has proceeded with a certain number of experiments co ncerning traffic li ght oriority. Such action seems difficult to out into effect due to traffic constraints (traffic li ghts timing, coordination, ... ). Neve rtheless, a few privileged areas can be found, such as one way streets with reserved bus lanes.

The efficiency of these devices has been confirmed by several years of use and now one or more terminal points of 100 routes are equipped; the functional and technical definitions (using computers) of this devi ce provided by recent studies, will permit the renovation of the oldest ones and a wider usage.

Systems using beacon has been installed in Ne uillysur~Seine next Paris (6 crossings, 2 routes (45 buses) on the lane concerned, 3 routes on the oeroendicular axis). Resul ts obtained are encouragi ng : running times throu gh the zone reduced by 20 % and, which is more important looking at re gularity, standard deviation of their fluctuation reduced by 30 %.

However it is clear that the possibilities of re gulation centers are enhanced by an exact knowledge of the buses' (and, of course, of the driver's) availability. The tracking process es, as stated above, form an indispensable complement, the precision of which is essentially a ~e lated to the line's natural ins tabi l i ty.

Global gain (time gain x number of passengers) on the previleged axis was about 84 or 117 hours a day, depending uoon the direction; global loss on the crossing axis was 31 hours.

Present realizations show that radiotelephone bring a fairly satisfactory solution to this pr ob lem in many cases. But for more complicated situations it se ems useful to have more pre c ise data on perturbation develooment in order to reflect their effect on terminal points as soon as possible. A test was made several years ago when two lines were equioped with beacons to detect the passing of vehicles a few minutes before their arrival at terminal. But contraints involved by the use of beacons are such that this solution is not fully satisfactory.

Global gain which could be obtained are related, particularly, to the relative values of buses schedule headways and traffic light cycle duration. Other exoeriences are going on in Paris and corroborates the results above, it can be seen also that the number of bus stops at traffic lights reduces by reduces 30 %. We must notice that complexe regulation problems cannot be solved only by reasonning, and that it is useful to make practical experiments in order to have a powerful implement available: computer simulation. Construction is now under way of a complete model to be supplemented by data collected on the routes.

SECA~A

is a perfect imolement to study line control prob lems. At the present time, we have only reoro-· duced the terminal control principle in the system, the superintendent's action being determined in relation to the information on bus locations given by the display, later an automatic algorithm, not studied yet, should be taken in consideration.

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as SECAMA should permit to see more distincly into the problems involved and to know if users will benefit from investment in more sophisticated systems. The idea of their integration on board must then be discussed, the equipment of a great number of vehicles being a positive factor to such integration.

6 - Passenger control Previously carried out by soe cial attendants who checked passengers' tickets, the reduction of the bus crew to one man, the driver, has made it necessary to automate the task by electromechanical devices. Automatic control (reinforced by soot checking designed to catch fraud) becomes more complicated when various transportation systems with different fares are involved as is the case in Paris speciallv since 1975.

It must be reminded that the 200 bus routes of RAT P are very diversified and the operational difficulties make this diversification obvious. The graph in the appendix gives a characteristic parameter of runs lost due to traffic irregularities; using this graph we could define zones in which the efficiency of different means of following or controling traffic seems the best.

This is why a study \./as be gun to examine the possibilities for use of ma~netic ticket checking like that of the subway system, operational since 1974. These studies are based on an experiment of self-contained devices using microprocessors in two subway stations, a te ch ni ca l process unlike that now operating in the whole of the urban syste'll.

The availability of the system is also a factor which cannot be forgotten. The technical limits of an emb arrassed envi ronment, such as that of a bus, make it necessary to accept a breakdown rate which could be high with respect to the size of the fleet; as comolexity generates fragility, a compromise must be achieved.

7 - Passenger information Several ideas concerning oassenger inf ormation, in real time or not, are under study a ll over the wor ld (visu a l display sh owing the time of the last bus passage or next bus passage, teleph one information on request) but, at first sight, it does not seem simple to find sufficiently general and economical solutions which suit all bus stops and for the moment RAT P uses a telenhone service which should be developed in the next few years as Dart of oublic transportation promotion.

It seem useful to point out that the different processes or systems developed in France (Besan~on, Toulouse, ... ) as well as in many other countries, are efficient in some situations but note in other ones. If the experience of other cities can be beneficial, it cannot be applied directly to a system as complicated and diversified as the Paris bus system. 9 - Conclusion

8 - Synthesis We have just seen that automation is gradually becomin g operational in the Paris bus system. It is being done prudently. The use of equipment such as radiotelephones, whose usefulness seems obvious is being developed. Other techniques however, need further investigation their costefficiency ratio being difficult to obtain. The coming years should bring about conclusions resulting from present experiments.

We have here above jus t reviewed the "panoply " of functions for which automatization is under way or under study. Several different kinds of questions can be distinguished. An imorovement in the quality of public transpor~ tation so as to meet the oublic demands will soon be made easier thanks to computer processing which collects its datas from devices now being tested on a sample part of the fleet.

BIBLIOGRAPHY Cl) - H. DEKINDT

As far as action on the vehicles is concerned, the radiotelephone seems indisoensable to insure the necessary contact between headquarters and driver (in the same way as it proved itself indispensable for the subway system which is entirely equipped since 1974, terminal departure control, which is the basis of re gulation, has also been developed.

"Simulation d 'une ligne d 'autobus" ler Symposium international sur la regulation du trafic VERSAILLES (France) - Juin 1970 (2)

At a more advanced stage is becomes difficult to determine which imorovements are justified, particularly because the economic aspect cannot be neglected and the cost of any equipment needed represents a high percentage of the vehicle global cost. But it can be seen that there exists a potential need of transmittin g and processing data to and from buses. Evaluating a system such

~

RAT P Optimisation des caracteristiques d'exploitation des lignes urbaines du res eau routier - Decembre 1970

(3) - M. CASSY et A. SNITER "Systeme experimental de controle automatique du mouvement des autobus" 2eme Symposium international - Regulation du trafic et systemes de transports MONTE~CARLO - Septembre 1974

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(4) - E. HEURGON et R. HERVILLARD L'habillage par ordinateur des horaires des lignes d'autobus Revue de l'U.I.T.P. - Janvier 1975 (5) - R. FAURE Etablissement automatique des tableaux de marche et feuilles de service dans un reseau de transport 7eme conference I.F.I.P. sur les techniques d'optimisation NICE (France) - septembre 1975

(6) - E. HEURGON et N.

P~ESENT

Construction automatique des horaires d'une ligne d'autobus 7eme conference I.F.I.P. sur les techniques d'optimisation NICE (France) - Septembre 1975 (7) - M. CASSY

Les systemes d'aide a la regulation Journees de l'Association pour le developpement des techniques de transport, d'environnement et de circulation (A.T.E.C.) PARIS (France) - Decembre 1975

~ runs percentage on RA TP bus sys tem (december 1975) L05t

Number of routes

Routes on which operation is fairly easy

60

Radiotelephone

Route! for which a wilful action on traffic is necessary

Terminal points control

40

•Priority on

traffic lights

Precise trackin g of buses

20

0,2

0,6

1,4

2

3

% lost runs

72