Copyright
IIT Kharagpur
Chapter 1 Introduction
1.1 MOTIVATION 1.1.1 General
An efficient transportation system acts as a catalyst for accelerating the economic growth and development of a country. The growth in population and travel demand over time necessitates the up-gradation or improvement of the transportation system from time to time. A transportation system is normally described by a set of attributes and their levels.
Several alternatives for improvement can be formulated by suitably changing the levels of some or all of the attributes. The two major aspects in evaluation of alternatives for improvement are the demand to be served and the benefits to be offered to the users. The demand modeling is an integral part of improvement planning as the revenue generation directly depends on the demand served, which in turn influences the viability of the system. The demand, again, depends on the nature of improvement and the socioeconomic characteristics of the users that influence the choice decision. Often, an improved transportation system is offered with an increase in the direct cost of travel to users (e.g. toll for road improvement, higher fare for mode improvement etc.). In such cases, the additional user charges should be related to user benefits. Sometimes user may not be charged in spite of the benefits offered. In either case, user benefits become vital inputs in evaluating the alternatives for improvement. Moreover, the possibility of attracting users would be high when the benefits offered by a system are more. Altogether, estimation of user benefits is a crucial component in improvement planning of transportation systems.
The saving in travel time is recognized to contribute to user benefits arising from transportation improvements as majority of the transportation infrastructure projects offer savings in travel time. However, an improved transportation system may also provide benefits to user by improving the qualitative attributes of travel such as comfort, aesthetics, vehicle condition, etc. Though the qualitative attributes may contribute to a great extent, their role is often ignored in the estimation of user benefits and evaluation of alternatives. The exclusion of such benefits may lead to a bias against improvement plans, especially in developing countries where the qualitative aspects (ex. condition of vehicles, comfort etc.) of transportation systems are generally poor. Therefore, it is vital to consider all the relevant attributes, both quantitative and qualitative, for rational estimation of user benefits resulting from transport improvements.
Copyright
IIT Kharagpur
User benefits in the context of transport improvement may be perceived as a reduction in the disutility of travel. Disutility of travel is expressed using relevant quantitative (e.g.
travel time, waiting time) and qualitative (e.g. travel comfort, internal appearance) attributes. These attributes generally have different measuring units, and therefore need to be transformed to have a common unit for comparison or aggregation purpose. When monitory attribute is involved, the transformation is simple and the transformed value associated with each attribute is generally termed as Willingness-to-Pay (WTP) value.
Aggregation of such WTP values, for the attributes describing an alternative or system is Generalized Cost (GC).
Modeling GC is a complex exercise as it involves valuing of quantitative and/or qualitative attributes. Valuing of attributes depends on several aspects such as type of data, response technique used, modeling technique and specifications, socioeconomic characteristics of users, trip characteristics of users, etc. Several attempts have been made by researchers for valuing travel time savings (Bradley and Gunn, 1990; Carlsson, 1999; Hensher, 1994;
Hensher, 2001; Hess et al., 2005). On the contrary, only a few works have been documented in the literature on valuing qualitative attributes (Hensher and Sullivan, 2003;
Hunt, 2001). Moreover, majority of the works reported in the literature are based on data from developed countries. Therefore, there is a need to initiate attempts to explore the significance of both quantitative and qualitative attributes in user benefits especially in the context of developing countries.
1.1.2 Scenario in Developing Countries
The operating conditions of transport systems in developing countries are generally poor with longer travel times, over-crowding inside vehicles, age old vehicles with high noise level, unpleasant interiors and exteriors of vehicles etc. as common features of transportation system. Increasing investments are now being made in transportation sector for the improvement of roads and transportation systems in developing countries, like India, in an attempt to improve the mobility of the people and transportation of goods. It is essential at this stage to have rational estimation of user benefits while evaluating alternatives for improvement of roads and transportation systems.
In the developing countries, valuing of travel time and other attributes is not done extensively due to insufficient empirical evidences to support the conventional models.
Copyright
IIT Kharagpur
with an exception to a couple of works in urban India (e.g. Arasan et al. 1996; MMPG 1998; Praveen and Rao, 2002) and the recent works by I T Transport (2005) in Bangladesh, Ghana and Tanzania. Most of these works that have attempted valuing of travel time using either revealed preference (RP) or stated preference (SP) approach.
Generally, an approach close to the “transfer price” or bidding process is used (e.g.
Thomas, 1983; MMPG 1998; Hine, Pangihutan & Rudjito, 1998). These approaches are considered to be irrational and hence the results produced could also be erroneous in some cases. This might have resulted in an apparent lack of interest among the transport professionals in developing countries to use estimated values for improvement planning of transportation systems (Ministry of Communications, 2001). Moreover, there are several practical challenges for carrying out travel behaviour experiments effectively in developing countries as the literacy rate is generally low and participation in such experiments is a new experience for participants which could lead to biased estimates. For adopting and customising the key design decisions on suitability of type of data, elicitation technique, attributes and their levels, size and number of choice sets, technique for data collection, locations, number of interviews, etc. to the local conditions, several rounds of pre-pilot discussions (focus groups) and pilot studies might be required which would prove the projects expensive. In the absence of extensive research in developing countries for estimating travel time and other benefits, savings in vehicle operating cost are used to assess improvement plans/investments. This emphasizes the need to investigate and suggest a rational methodology for estimating user benefits arising out of transportation improvements especially in developing countries.
In general, the WTP values are estimated by analyzing preference data collected using traditional rating or ranking or choice techniques. Application of stated choice (SC) experiments for estimation of WTP values is yet to be explored adequately in developing countries. Moreover, when the SC experiment is prepared with a view to collect repeated responses to improve the richness of the data (with multiple choice sets in a questionnaire), it is necessary to investigate the possible correlations among repeated responses obtained from the same individual. In addition, the socioeconomic characteristics of individuals such as age, income, household size, etc. and/or trip characteristics such as trip purpose, trip length etc. may have influence (preference heterogeneity) on the mean estimates. These issues such as correlations among repeated responses, taste heterogeneity, etc. are generally not well addressed during estimation of WTP values around the world with few exceptions in developed countries.
Copyright
IIT Kharagpur
1.2 OBJECTIVES AND SCOPE OF THE WORK
The broad objective of the present work is to investigate and demonstrate rational approaches for improvement planning of transportation systems while addressing several practical challenges in carrying out travel behaviour analysis in developing countries. The work also aims to evaluate improvement alternatives with due regard to user costs/benefits emerging from the travel behaviour analysis expressed as generalized cost (GC) of travel, and operational viability with respect to two specific real world transportation problems.
Estimating WTP values for various attributes of travel is an integral part of GC modeling exercise. One of the interests of the present study is to understand the preferences with respect to the qualitative attributes in the developing country context. For valuing attributes it is necessary to design a suitable survey instrument, collect behavioral data, analyze the same using suitable modeling techniques and model specifications. Although behavioral data can be analyzed using several modeling techniques, the scope of the present work is limited to using logit modeling techniques namely the Multinomial Logit (MNL) and the Random Parameter Logit (RPL). The literature indicates that distributional assumption of random parameters, decomposition effect of socioeconomic and trip characteristics on mean estimate(s) of random parameter(s), correlations among choice responses, etc. are important considerations in the process of developing RPL models.
Accordingly, all these aspects would be investigated in the present work in order to understand their effects, if any, on model goodness-of-fit and WTP values.
The scope of the present work is summarized below.
• Designing of Survey Experiment
• Conducting Revealed Preference and Stated Preference (Choice) surveys, traffic surveys, etc. for collecting data
• Developing Utility equations using Logit models o Multinomial Logit model
o Random Parameter Logit model
Assuming no correlations among responses
Assuming correlations among responses from each individual
Accounting for heterogeneity around mean of random parameter(s)
• Developing Generalized Cost of Travel model
• Application of Generalized Cost of Travel for improvement of transportation systems
Copyright
IIT Kharagpur
The two specific transportation problems considered in India are distinct due to their nature and region of operation. A brief description of the two case studies considered is given below.
1.3 CASE STUDIES SELECTED
Two specific problems considered in the present work include a bus transportation system in a rural region and a taxi system in an urban region.
1.3.1 Rural Bus System
In majority of the developing countries like India, private vehicle ownership is low in rural regions and rural passengers are generally captive to bus transportation system for their travel needs. As rural population constitutes more than 70% of the country’s total population (Census, 2001) and bus is the most common and only form of public transportation in rural regions, the rural bus system has a vital role to play for the economic growth. However, the rural bus transportation system generally exhibits poor operating conditions in the form of low travel speeds, longer headways, relatively high discomfort levels (i.e. crowding inside buses) and low reliability. In addition, in the recent years, bus fares have been increased at regular intervals due to frequent increase in the price of petroleum fuels all over the world. However, poor quality of operations in bus transportation system continues. Despite poor operating conditions of rural bus transportation in India over several decades, adequate attention has not been paid for improvement of rural bus services. No attempts have been made to study the rural bus system users’ preferences with respect to travel time, headway, comfort conditions inside the bus etc. and use the same for improvement planning. While improvement of rural bus service has become a major issue in the context of rural transportation in India, investigation on trip makers’ willingness to pay (WTP) with respect to attributes of rural bus service and improvement planning with due regard to user behaviour and operational viability has become a pertinent research problem.
In order to study rural bus users’ preferences for improvement in the attributes of bus system and demonstrate their use for improvement planning, a rural bus route which connects a district headquarter (Medinipur) and a tourist place (Digha) in West Bengal, India is considered. The travel demand along the study route is served by bus services.
The buses generally take about 4.5 to 5 hours to cover a distance of 137 km. and serve about 16 major stops and around 35 intermediate stops. About 42 services run between
Copyright
IIT Kharagpur
these two places with several other overlapping services. The study route is shown in Figure 1.1.
Figure 1.1 Map showing the Bus route considered for the study
1.3.2 Urban Taxi System
Intermediate Public Transportation (IPT) i.e. Taxi system is one of the many facets of urban transportation system which cater to a significant part of travel demand. Taxi system in several developing countries largely consists of age old vehicles. With low acceleration/deceleration capability and maneuverability, these vehicles aggravate congestion and take more travel time. In addition, these vehicles are less fuel efficient, more polluting and prone to frequent breakdowns. In the recent years, taxi fare has been increased at regular intervals due to the frequent increase in price of petroleum fuels.
However, with no attempts made to improve the attributes of taxies, the poor quality of service continues with a resulting declining trend in patronage. Increased fares and less attractive operations are leading to the loss of patronage. Policy makers and practitioners are presently in search of measures for improving the system not only for the system’s survival but also for greater social benefits. Of late, researchers/policy makers are coming up with an idea of replacing age-old vehicles with new ones which are fuel efficient, comfortable, less polluting etc. Though, the governments have been successful in restricting the use of age old buses and private vehicles, replacement of age old taxis has become a major challenge in most of the cities primarily due to socioeconomic constraints.
Copyright
IIT Kharagpur
the government bodies are now in dire need for an acceptable mechanism of implementing the same.
Replacement of an age old taxi with a new one is expected to bring some benefits to users.
The knowledge of such benefits is essential as users are expected to pay an increased fare level in lieu of the vehicle replacement. However, no database is available to understand such benefits in a quantitative manner although poor vehicle condition of taxis is a concern in many countries. Therefore, quantifying user benefits and suggesting a rational mechanism for replacement of old taxies with due regard to user benefits, operational viability, etc. has become a pertinent area of research.
In order to understand taxi users WTP for different attributes of taxis, a taxi system in Kolkata, where more than 34,000 taxies are operational is considered. Around 45% taxies in Kolkata are aged beyond 15 years with some even beyond 30 years (WBPCB, 2001) and only 15 to 20 per cent of the taxis operating in the Kolkata, are relatively in good condition.
It was observed that, in Kolkata, average travel speeds vary between 7km/h to 10km/h.
Longer travel time, poor appearance (both internal and external), high noise level, and high air pollution are common features of IPT system in Kolkata. A typical Kolkata taxi is shown in Figure 1.2.
Figure 1.2 Typical Kolkata Taxi
1.4 CONTRIBUTION
The present work contributes in investigating and laying out a rational mechanism for understanding the user preferences and quantifying the same in the context of a developing country where several practical challenges are encountered in adopting and customising the key design decisions on suitability of type of data, elicitation technique, selection attributes and their levels, size and number of choice sets, technique for data
Copyright
IIT Kharagpur
collection, locations, number of interviews, etc. and utilising the same in the evaluation of alternative improvement plans for two specific transportation problems i.e. (a) improvement of rural bus service, and (b) improvement of taxies in urban areas.
The application of the knowledge of WTP for improvement planning is a practical challenge addressed in the present work. Though specific, improvements to rural bus transportation system and replacement of old taxis are two crucial but different problems. In the case study of rural bus service, the travel behaviour analysis is used for demand modelling as well as for obtaining optimal parameters (i.e. number of buses under two different services, fares, etc.) with due regard to user costs (obtained from WTP values) and operational viability of both the services. For the case study of taxies in Kolkata, the travel behaviour analysis is used for estimating the benefits resulting from the replacement of old vehicles with new ones and the estimated benefits are utilized for evaluating replacement schemes.
1.5 ORGANISATION OF THE THESIS
The Motivation, objectives and scope of the present work along with brief description of the case studies are discussed in Chapter 1. Chapter 2 deals with the approach and methodology followed for the present study covering preference elicitation techniques, type of data, selection of attributes and their levels, generation of alternatives, data collection and analysis. Chapter 2 also includes a brief discussion on the theoretical background of econometric models such as multinomial logit (MNL) and random parameter logit (RPL) for analyzing the preference data. Analysis of the behavioral data using MNL and RPL models, estimation of WTP values and Generalized Cost of travel models with respect to two case studies is presented in Chapter 3. Chapter 4 covers the application of GC models for improvements in transportation system with reference to the two case studies. Finally, Chapter 5 presents some conclusive remarks and the findings from the work, with a note on future works to be carried out. Chapter 5 is followed by References.
1.6 SUMMARY
The importance of user benefit estimation in improvement of transportation systems, the role of quantitative and qualitative attributes in user benefits, aggregation of user benefits to form generalized cost of travel and utilization of the same for improvement of transportation systems are the motivation for the present study. Objectives and scope of the present work along with a brief description of each of the case studies considered, in a
