MODELLING OF INTEGRATED BUS ROUTES WITH RAPID TRANSIT SYSTEM

Abstract

The migration of population from rural areas to urban areas has put a severe pressure on the infrastructure of urban cities. In India, according to 1991 census, out of the 230 million urban population, 65 percent live in cities with more than 0.1 million population and nearly 35 percent live in 23 metropolitian cities each with a population more than one million. Besides the heavy concentration of population in urban areas, the population of vehicles has greatly increased and continues to increase. In 1970, the registered motor vehicles in Delhi was 0.24 million which increased to 1.8 million in 1991 and 3.0 million in 1998 resulting in the-.present level of congestion on Delhi roads. The population of Delhi was 9.37 million in 1991 which is expected to rise to 12.2 million by the Year 2001. The number of accidents is highest in Delhi amongst all metropolitan cities in India. On an average, 5 persons are killed in Delhi every day in road accidents. The current public transport demand is met mainly by bus services which carry about 4.5 million passengers daily. This demand is expected to grow to 11 million trips by the Year 2001 which cannot be met by increasing the buses and bus routes. Therefore, other modes of public transport are required to cope with the needs of the future. A properly planned Mass Rapid Transit System (MRTS) has always played a vital role to relieve the congestion level on roads although it requires high initial investment. It is evident that even MRTS fails, in absence of proper urban public transport planning. The obvious Delhi example is the Ring Railway (35 km length having 23 railway stations) with limited EMU services. The present utilization of Ring Railway by urban commuters is even less than 25 percent of its designed capacity. Most of the stations on this rail-route remain deserted with very limited travel demand. (i) To provide relief to the commuters, best possible use of the available public modes of transport must be made through an adequate interface of rail based and road based public transport system. An integrated approach consisting of bus route and RTS corridor can be the only panacea if it can transfer commuters from road based bus transit to rail based transit through convenient and efficient connections of bus and railway stations with feeder bus services. The objectives of the present study was, (i) to identify the existing bus routes parallel to RTS corridor, (ii) to formulate the concept of connectivity of bus stops on the route to RTS stations by feeder services, (iii) to develop a simulation model for the operational analysis of bus routes, (iv) to develop a model for the operational analysis of RTS, (v) to develop a methodology for integration of bus routes with RTS, (vi) to validate the developed models and (vii) to demonstrate the applicability of the methodology. The concept of integration which leads to the development of methodology consist of a bus route connected with RTS corridor through feeder bus services. The two options for a commuter are, (i) a direct bus route from origin to destination (ii) disembarking from bus stop to catch the feeder bus to reach the starting point of RTS station and (iii) disembarking at end point of RTS station to reach the desired destination by feeder bus. A questionnaire has been designed to estimate the transfer of commuters from road based bus transport mode to integrated system. A computer simulation model for operational analysis of bus route has been developed and designated as 'BRSM'. The computer program is written in FORTRAN 77 language and consists of a main program and eight subroutines. The input parameters considered for the above model are; link details, type of traffic control on the intersection, traffic signal settings, details of traffic system, details of bus system, origin of random numbers, length of simulation period, number of simulation periods, processing intervals, time in hours and minutes at which the simulation run (ii) starts. The outputs of the model are bus overall average speed, passenger waiting time, number of passenger boarding and alighting and total travel time of each bus. The model also predicts the effectiveness of the bus operation in terms of Passenger Waiting Index (PWI), Running Index (RI) and Efficiency Index (EI). Thecomputer program of RTS is written inFORTRAN 77 language. Themodel has been designated as 'RTSM'. The inputs required for the program are the number of lines, coaches per train, coach capacity, RTS passengers per day, surface served area, average trip length, number of stations, operating speed, population served and total stations with Park-n-Ride facility. Outputs of the model are printed in terms of average interstation spacing, operating speed, frequency of services and the total travel time between origin and destination. The model for integrated transport system has been designated as 'IBRTS'. The inputs of the model are the schedule time of feeder bus, schedule time of RTS, frequency of feeder bus, frequency of RTS, average speed of feeder bus/RTS, capacity of coach and number of coaches. The model predicts the travel time of feeder bus to the origin of RTS station and vice versa including the waiting time of commuters at RTS stations with total travel time and overall average speed. Suitable field studies and data collection prorgamme are designed to test the above models. A section of Ring Road of Delhi has been identified as bus route which starts from ITO bus stop and ends at Africa Avenue (Bhikaji Cama Place) bus stop. The identified section of RTS corridor (Ring Railway) adjacent to the bus route is from Tilak Bridge railway station to Sarojini Nagar railway station. The details of the bus route i.e., number of bus stops in each link, traffic volume (at mid block and at intersections), passenger boarding and alighting at each bus stop, signal timings at each intersection, capacity of the bus, traffic speed, bus overall speed, delay and headway at each intersection has been collected. The frequency, schedule of trains, number of passengers using RTS and the capacity of (iii) coaches were also collected. Passenger opinion survey for studying the switching of commuters from bus route to integrated system has been carried out using the stated preference questionaire. The bus route section from ITO to Africa Avenue consists of 19 links. The total distance of the section is 14.75 km. The section of the route passes through congested areas. Large travel time and long queues are formed at the intersections. The model predicts overall average speed, mean passenger waiting time and total travel time. Since, bus feeder services to connect bus stops to RTS stations are not available, the frequency of buses presently is too low and the service does not match the train schedule, therefore, suitable assumptions have been made with respect to operational parameters of feeder buses. The average speed of the feeder bus service is taken as 30 kmph. The transfer time between bus stops and railway stations has been taken as 2.5 minutes. The length of feeder bus route at the two ends has been taken as 1.45 km and 1.90 km, respectively. The average speed of RTS is assumed to be 30 kmph with a frequency of 10 minutes. The overall average speed and total travel time are computed using the above three models for the three systems separately. The Passenger Waiting Index (PWI), Running Index (RI) and Efficiency Index (EI) are computed for the bus route, RTS and Integrated System separately. From the analysis, it is observed that the integrated system is found to be more efficient in comparison to the use of bus route and RTS separately. To test the the efficacy, the validation of the above three models have been done. The validation of the BRSM model has been done with respect to total passenger boarding and alighting, time distance diagram of the buses, overall average speed and total service time of operation of buses on the route. The validation of the RTSM and IBRTS models have been carried out with respect to computed and observed values of overall average speed and total travel time. The variation in the computed and observed (iv) values of the above parameters are well within the tolerable limits and considered appropriate in such complex field situations. Applicability of the integrated model has been demonstrated by evaluating the impact of different operational strategies. The various strategies cover the changes made in the speed of feeder buses and RTS and frequency of feeder bus services. Evaluation of options through modelling not only saves the cost of avoidable experimentation causing inconvenience to the public. It also provides a quick and inexpensive way to evaluate several schemes and helps in developing new schemes to decongest the bus route sections and improve the level of service. It is expected that the concept and modelling on integration of bus routes with rapid transit system developed and presented here would be useful to developing strategies in solving the acute urban transportation problems. (