Innovations in Travel Demand Modeling, Volume 1: Session Summaries (2008)

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an individual’s personal world, and technologies for con- ducting surveys. The following points were covered in his presentation. • A number of trends can be identified relating to transportation, travel, and telecommunications in Switzerland. The number of people or locations that can be reached within 1 hour of travel time on the roadway system in Switzerland has quadrupled in the 50 years from 1950 to 2000. This trend has “shrunk” the coun- try. The trend in the real cost of telecommunications has declined dramatically over the past 70 years. The real cost of driving an automobile has also declined, although it is difficult to believe. Switzerland has experienced the suburbanization trend. Since 1980, the catchment areas of the largest 10 cities have increased in size. The fore- cast is for continued suburbanization and the overlap- ping or growing together of some regions. • A number of elements can be used to help explain travel behavior at the microscopic level. These elements include the generalized cost of the route- mode- location alternative, as well as budgets and longer- term commit- ments. Other elements include values, attitudes, and lifestyles by sociodemographics, an individual’s personal world or mental map, and an individual’s social network membership. Individuals are influenced by these ele- ments, which are not easily captured in travel diaries and other survey methods. Examining methods to obtain information on these elements is important to help advance activity- based travel models and other new fore- casting techniques. • A number of elements might be considered in the generalized cost of a route- mode- destination alternative. These elements include the time spent traveling, includ- ing schedule delays relative to the intended arrival time, monetary expenditures, the time spent at the location by type, activity expenditures, and the social content. Some of these elements address comfort and risk, while others are decision and time frame relevant. Including ques- tions in surveys to obtain information on these elements would be beneficial. For example, the risks associated with being late on trips for some activities may be higher than for others. • Considering individuals as “network actors” in a dynamic social context represents one possible approach. An individual’s personal world is influenced by his or her background and learning. Household location, social net- work geography, and mobility tools are linked to an indi- vidual’s personal world. One individual’s personal world is linked to the personal worlds of others through social capital, which includes elements related to stock of joint abilities and shared histories and commitments. • This concept raises a number of new research ques- tions. These questions relate to the ability to measure the social content of travel, the social network of geography, and the activity spaces. Other potential research ques- tions focus on techniques to measure the personal world and mobility biographies and on assessing changes in the transportation systems and the social costs associated with these changes. • The personal world may include local, national, and international transportation links. One possible approach to measure an individual’s personal world focuses on the personal world as a mental map and an expectation space. Potential techniques to measure these elements include sketching, think- aloud protocols, and spatial tasks. The personal world may also be thought of in terms of the activity space of visited locations. Potential techniques to measure activity space include diaries and Global Posi- tioning System tracing. Tracing by other techniques, such as payment methods, closed- circuit television, and tele- phone and computer use, raises privacy issues. • Travel surveys have been used to collect information on individuals’ trips and travel patterns. For example, a 6- week travel diary of a 24- year- old single woman, employed full time, reported a total of 216 trips. Possible techniques for collecting information on social network geographies include name generators and interpreters, diary- based prompting, and tracing contacts through e- mail, letters, telephone records, and other technologies. Obviously there are privacy concerns associated with the use of these tech- nologies. Measuring social content will also require new questions on travel surveys to obtain information on the individuals participating in the travel and activity and who is paying. Questions to obtain information on when the trip and activity were planned, who was responsible for making the arrangements, and if the activity has been undertaken previously are also needed. It is also important to obtain information on pets being taken on trips. One study found that a dog altered the travel behavior of a household. It is also important to obtain information on repetitive activities and trips, such as work, and infrequent or new activities and trips. Experience with the initial sur- veys indicated a 10% response rate for the long- duration travel diaries and a 10% response rate to the social net- work interviews, with the use of incentives on both the diary and the survey. A 15% response rate was obtained on mobility biographies without motivational calls, whereas a 30% response rate was obtained with motivational calls. No difference in travel and trip behavior was detected between the mobility biographies completed with and without the motivational calls. • A number of further efforts are being pursued and considered. These activities include semiautomatic extraction of data from e- mails and other written traces, experiments with social content questions in travel sur- veys and diaries, and integration of social network ge - ographies and mobility biographies. Experiments with activity and travel summary questionnaires represent another future effort. 61THE FUTURE OF TRAVEL BEHAVIOR AND DATA COLLECTION