Showing papers by "Marcela Munizaga published in 2013"

Estimation of a constrained multinomial logit model

Abstract: Identifying the set of available alternatives in a choice process after considering an individual’s bounds or thresholds is a complex process that, in practice, is commonly simplified by assuming exogenous rules in the choice set formation. The Constrained Multinomial Logit (CMNL) model incorporates thresholds in several attributes as a key endogenous process to define the alternatives choice/rejection mechanism. The model allows for the inclusion of multiple constraints and has a closed form. In this paper, we study the estimation of the CMNL model using the maximum likelihood function, develop a methodology to estimate the model overcoming identification problems by an endogenous partition of the sample, and test the model estimation with both synthetic and real data. The CMNL model appears to be suitable for general applications as it presents a significantly better fit than the MNL model under constrained behaviour and replicates the MNL estimates in the unconstrained case. Using mode choice real data, we found significant differences in the values of times and elasticities between compensatory MNL and semi-compensatory CMNL models, which increase as the thresholds on attributes become active.

Transport Survey Methods: Best Practice for Decision Making

Abstract: This book provides an international perspective on improving information to support transportation decision making. It comprises a selection of papers plus workshop syntheses from the 9th International Conference on Transport Survey Methods in Chile in November 2011. The conference was organized into 14 workshops with both paper presentations and discussions in the workshops forming the majority of the conference activity. The papers reported primarily on research pertaining to continuous improvement in transport survey methods — the backbone of the transportation data pipeline in most countries. But some papers also addressed the new ways in which innovation — notably technological innovation — is being applied to the capture and analysis of data to produce necessary information faster, better, and less expensively. The conference program built on a rich legacy of intellectual pursuits spanning the past two decades, and it is anticipated that the conference will continue into the future. Thus, the contents of this book represent a 5–10 year view through a moving window on the international state of the practice and concerns in transport survey methods.

Validating travel behavior estimated from smartcard data

Abstract: 0 0 1 332 1829 universidad de chile 15 4 2157 14.0 Normal 0 21 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} To obtain travel information from smartcard data is a growing tendency. Many researchers have foreseen the opportunity of obtaining high quality information at very low cost, and therefore have developed tools to obtain valuable information from the original data generated as a side-product of the operation of transit systems. However, most authors recognize that the process of estimating destination, route and activities from smartcard data involves several assumptions, and the results need to be validated. We have conducted such validation for the set of methodologies used to input boarding position, alighting stop and route chosen for the case of Transantiago (public transport system in Santiago, Chile). To do so, we have used three sources of information: information from the same database used to make the estimations (endogenous validation), information from a detailed origin-destination survey applied to a sample of 300,000 metro users, where a small percentage of them provided their smartcard id for validation purposes, and personal interviews to a small sample of volunteers who provided all their travel and personal information. The endogenous validation was mainly used to detect errors and improve the methodology. The large sample of OD surveys was used to compare the route chosen by the users within the Metro network with the route assigned by the model (minimum cost). The small sample of metro users who answer the OD survey and also provided their card id, and the sample of volunteers were used to validate the more strong assumptions of the model: alighting estimation and purpose assignment. The results of this exploratory validation analysis are very promising. The endogenous validation showed very reasonable estimations, and helped to detect some errors that can be easily corrected with slight modifications to the previous methodology. Both the OD survey and the personal interviews showed that the estimation of the boarding site is very precise, and that the estimation of alighting stop is reasonably good in estimating the exact alighting site, and reach levels over 95% of accuracy at a more aggregate level.

Measuring User Satisfaction in Transport Services: Methodology and Application

Abstract: Purpose — New methods of measuring user satisfaction in transport services have been proposed and applied in the literature. In this paper, we compare three alternative measures for estimating user satisfaction: the numerical rating, the ordinal rating and the choice. Approach — We analysed these measures considering their differences and limitations and the models that use these measures as dependent variables. We developed and applied a methodology to build these models. It comprises a preliminary qualitative analysis and a quantitative survey to identify the most relevant attributes of the satisfaction function, and a stated preference survey to obtain information of the alternative satisfaction measures for modelling purpose. Findings — The ordinal rating may be a better user response to estimate satisfaction than score and choice based on its characteristics. The results obtained in the application reinforced this approach. Research limitations — It is assumed that choice, score and ordinal valuation depend upon a latent stochastic satisfaction function of the same attributes. Further research is needed to analyse this assumption and how these responses vary according to the context for decision and exogenous factors, including the response scale of ratings. Practical implications — Gathering alternative satisfaction responses simultaneously from users allowed for the consistency analysis and filtering of data, which greatly benefited the model estimation process. Originality/value — The paper provides a methodology to estimate user satisfaction models in transit services, which can be applied in other transport services. The conceptual analysis and the application suggest that ordinal ratings are key user responses to uncover the underlying satisfaction function.

Towards a Reliable Origin-Destination Matrix from Massive Amounts of Smart Card and GPS Data: Application to Santiago

Abstract: Purpose — Automated fare collection systems implemented in public transportation systems in the last decade have provided a massive, continuous and low-cost source of reliable travel information. A direct and useful application of these data is the estimation of highly representative, although not bias-free, origin-destination (OD) matrices. Methodology/approach — We discuss several issues with current OD matrix estimation methodologies, such as fare evasion and group travel, and their derived biases, specifically focusing on the Santiago (Chile) case. We also propose and apply two methods of validation: endogenous and exogenous validation. We elaborate on some methodological improvements that could be implemented to upgrade the activity estimation mechanics. Findings — Several sources of bias in the estimation of OD matrix estimation from passive data are pointed and some solutions proposed. We apply improvements to existing methodologies and increase the success rate of trip estimations. Practical implications — The reliable estimation of public transport OD matrices from passive data results in a valuable planning tool for both transit authorities and operators, much more representative and with less errors and biases that conventional data collecting techniques. Originality/value of paper — This paper is one of the first works to deal with the subject.

Indirect Measurement of Level of Service Variables for the Public Transport System of Santiago Using Passive Data

Abstract: Purpose — The introduction of new technology to public transport systems has provided an excellent opportunity for passive data collection. In this paper, we explore the possibility of automatically generating level of service indicators that could be used for operation planning and monitoring of Transantiago, the public transport system of Santiago, Chile. Design/methodology/approach — After basic processing of the raw automatic vehicle location (AVL) and automatic fare collection (AFC) data, we were able to generate bus speed indicators, travel time measurements and waiting time estimates using data from 1week. The results were compared with manual measures when available. Findings — The advantage is that these measurements and estimates are reliable because they are obtained from large samples and at nearly no cost. Moreover, they can be applied to any set of data with a selected periodicity. Research limitations — The scope of this research is limited to what can be observed with AVL and AFC data. Additional information is required to incorporate other dimensions, such as personal characteristics and/or more detail in the origin/destination (OD) of the trips. Practical implications — Nevertheless, these results are valuable for the planning and operation management of public transport systems because they provide large amounts of information that is difficult and expensive to obtain from direct measurements. Originality/value — This paper proposes tools to obtain valuable information at a low cost. These tools can be implemented in many cities that have certain technological devices incorporated into their public transport systems.

Cálculo de indicadores de calidad de servicio del sistema de transporte público de Santiago a partir de datos pasivos

Abstract: Quality service measures are calculated for the public transport system of the city of Santiago using smartcard bip! transactions and buses GPS data. After developing criteria to filter atypical trips (that represents less of 10% of the estimated trips), quality service indicators are defined. The results obtained are quite promising, because indicators that are useful for planning, reliable and low cost are obtained. This allows thinking that the traditional measurement methods can be complemented – and in some cases replaced– by these new data sources.

Estimación de zona de residencia en base a sistemas tecnológicos de transporte público

Abstract: Public transport systems with electronic fare collection devices continuously store data related to the trips made by the users, which contain valuable information. However, when the card is not personalized, there is no socioeconomic information, and that constrains the analyses that can be made. This works presents a method to estimate zone of residence of the users behind the cards, which will allow socioeconomic variables imputation by zone of residence, enriching the analysis possibilities. We also show travel time, transfer time and time use profiles by aggregate zone, showing that indeed there are differences.