This article is the first episode of a series that I am already excited about for the next one. I hope that the last episode will not arrive too soon. The series aims to offer an oral history of travel behaviour modelling. Inspired by the IATBR conference in Santiago, Chile, two eminent professors who have significantly contributed to the field of travel behaviour research have been nominated for this episode. They have jointly and independently shaped the field, making their stories quite intriguing. Due to the considerable time difference between Sydney and Santiago, we discussed personal and professional topics through an online meeting. With the help of Sebastián Raveau, I hosted the interview, which was heated at some points with a pinch of humour, politics, and signals of deep friendship. Juan de Dios and I joined the meeting first. When Sergio joined, he was welcomed by Juan de Dios with a comment about not being punctual; Sergio rebutted, reminding a personal story about him and his mother both always being five minutes early for whatever meeting they had, not to make the other person wait. Before the meeting, I had shared my questions with them, and they both prepared their answers with some stress on whether their responses would match across shared memories and events by the other.
I started my questions about their preceding and proceeding families. Born in 1949, Juan de Dios grew up in a well-off family, and later, when he was an adult, his father became extremely wealthy. Unlike Juan de Dios, Sergio was born in the second half of the 20th century (as he jokingly stated), to a medical doctor and a nurse, both from the University of Chile with two younger sisters. Expectedly their children are highly educated. Juan de Dios married a professor of architecture who also studied in the UK. His parents were not university educated, and a nurse educated his mom at their farm. On the other hand, his father was the son of a wealthy dad but ended up being poor initially. Like Juan de Dios, Sergio entered the university at 16 andwas always the youngest among his peers, which was not quite attractive when finding a girlfriend was the concern. After marriage, Sergio and his wife – a professor of structural engineering - applied to UC Berkeley and MIT with the condition that they would accept the one offering them both admissions. MIT was the “lucky” institute to have them both eventually.
Both interviewees confirmed that they would have gone through the PhD path if they would go back in time. When they graduated from undergraduate between 1971 (Juan de Dios) and 1973 (Sergio), their undergraduate degree was heavily loaded with mathematics and basic sciences, a French style. As a reference Transportation Science and the Transport Research series were born in 1968. There was no transport engineering training then, only a bit about infrastructure planning and design. The first three years of civil engineering were rather dull for Juan de Dios until he was introduced to industrial engineering and operations research. After graduating, he visited Pilo Willumsen in London (he had created the year before the now Department of Transport Engineering at PUC and was doing an MSc at Imperial College), who convinced him to join this new Department. In 1973 he ente red a Master of Science at Leeds University, where Huw Williams supervised his three-month thesis leading to a paper in Transportation Research. He came back to do a PhD at Leeds in 1977, but as a research officer (with the luxury of even having a secretary) instead of a student. In 1980, when he ended his PhD, he organised a discrete choice modelling conference in Leeds, which many important outside scholars, such as Hensher, Manheim and Sheffi attended. This is something for younger academics to think out of the box and be creative about initiatives that may becomemajor achievements if persistently pursued. At that conference, he rejected a paper identified to be out of the scope and theme of the conference, which was authored by a Nobel Prize winner, although the author was unknown to Juan de Dios then; otherwise, it would have indeed been accepted, he says.
Like Juan de Dios’s journey to the UK, going to MIT with his wife and his 1.5 years son led Sergio’s journey to learnsolid foundations of microeconomics, operations, research, statistics, and probabilities from transport engineers and economists who were well knowledgeable in these areas. Sergio commented that his PhD panel included future Nobel Prize winner Daniel McFadden, soon-to-be head of the Economics Department at MIT Ann Friedlaender, and Yossi Sheffi, then a rising star in the field of transport networks analysis known for being tough. Building theories and concepts nurtured and reinforced by both fields of knowledge synthesise Sergio’s research history. Looking back to those days, he recalls that as a couple, he and his wife produced three theses and a second child in a little more than two and a half years, something that was not intended as a record (but that very likely is).
In the view of the two scholars, research appears to be more inclined toward tool development than observing people’s behaviour and developing theories and models to interpret and explain the observed behaviour. Like the case of time use modelling and understandingthe supply side, the theory is still slim. Many tools and formulations have been developed for measuring demand, although the tools are not shaped based onpeople’s behaviour. Tools should never be on top of the concepts and theories. Tools and algorithms are developed as needed when theory needs them. However, this phenomenon has changed, especially with the advent of data analysis “tools”.
In addition to economics, operations research and fundamentals of transport engineering, both scholars happened to be talented musicians. Juan de Dios feels he inherited it from his mother, an excellent guitarist and singer. The guitar was the first instrument Sergio also started, as he was also trained with his family and ended up writing many songs, which have never stopped emerging. They started performing together during the famous PTRC Summer Annual Meetings, now the European Transport Conference.
They also performed at the 1994 IATBR conference in Chile, where attendees were isolated in the Andes,and some guitarists got together and performed and sang. Hani Mahmassani joined Sergio and Juande Dios and received high praise from the attendants. This motivated DavidHensher to organise a party at the next WCTR conference in Sydney, handling Sergio and Juan de Dios, a couple of guitars. Sydney’s music performance appeared to outperform the readership of the presented papers, and Sergio suggested that his writings started getting read after their performance. Later Dan McFadden also praised them for their show at an IATBR conference, and they are still hoping he could equally praise their work (which McFadden actually did when presenting Sergio’s book in 2007).
Perhaps the best story about their singing duo comes after they performed a song by Joaquin Sabina, a famous Spanish love songwriter, at the European Transport Conference at Brunel University. Sergio sang,and Juan de Dios did a simultaneous translation for the huge audience in the bar. They both absolutely loved this translation idea, possibly because they were a bit drunk, as Juan de Dios suggested. In England, bars close at 23:30,s o a young waitress politely asked them all to leave, but instead, they started singing Elvis’ Devil in Disguise“… you look like an angel; walk like an angel; talk like an angel”, and the girl left the bar. The day after, Kay Axhasuen invited Sergio to the bar where the same girl served them beer before saying, “oh no, you again” when she recognised Sergio. On another exciting occasion, both guitarist professors were invited to perform in Leeds with the famous Australian band “Super Trump”, only to realise later that it was the ITS Leeds “Super Tram” band, superb but not as famous as the Australians; this performance by the Red Hot Chile Professors is available on YouTube.
Music appeared not to be the end of the fantasy of these two grand scholars when I realised Sergio had been hosting a radio show for 33 years and was selected as the second-best host in 1993. He started a show about music with a mixture of discussions and commentson serious matters in plain language, e.g. thephilosophers of the Frankfurt School of thought, becoming a vitalstation radio show. Then in 2002, he moved to the University of Chile’s radio station, keeping his pseudo name (Argos Jeria, an anagram) with commentaries on daily life, including travels, politics, love and music. The commentaries were later transcribed into articles and eventually into five books of chronicles. Argos interviews people on his show. Once, he interviewed himself as Prof Sergio Jara-Diaz. At the end of the show, the host (Argos) asked the professor (Sergio) what you do besides being a professor, and he responded, “I have a radio show”.
Switching gears to more professional topics, we discussed the benefits and drawbacks of the NorthAmerican and British PhD education systems, where one puts more emphasis on the thesis, and the other has a heavily loaded start with the course work. The combination of both seems to be the preferred system proposed and implemented in Chile, each borrowing the best of what they got from MIT and Leeds. Another exciting aspect of North American universities is sending students to other institutes to learn from others. On a separate note, Juan de Dios explicitly shared his dislike of the MIT system for hiring a new academic where a few were hired, and only one may be promoted. Interestingly, Juan de Dios and Sergio returned to Chile due to a role they felt they had in their own country. Their return created a culture and prestige for the transport community of Chile. Still, they recommend that their students explore the best universities worldwide. However, they have strong academics like Marcela, who stayed in Chile due to family reasons. Sergio advises PhD students to select the right person for a thesis, not just the best university. Juan de Dios added then that his final advice for his students going out of Chile is to come back as they are more needed in Chile than outside.
In 1978, they started collaboratingon research, which ended in their first publication, although they do not have many together, on the sensitivity of the value of time to the model specification, which was a by-product of a project financed by a Canadian foundation. They are both immensely proud of that work as one of the first models accounting for the non linearity involved in the utility function and correcting for the impact of income.
In response to my question on the future of travel behaviour, they alluded to the significance of environment, micro-mobility, sustainability and time use in future studies. Sergio commented that he strongly believes that people will still value their time and will pay to reduce it. So, time use is a crucial topic that will stay essentially the same as land use, as we should note that we can travel in time without changing location, while as we change our location, time elapses. Further, a transformative shift in people’s behaviour is expected to be observed regarding environmental aspects of transport. Nonetheless, properly pricing the system to assist this paradigm shift is crucial. Sergio added that those lending institutions investing money into building new highways have significantly contributed to the field but horribly negatively.
My last question was about their opinion on which scholars significantly contributed to the travel behaviour field. We joked that we have two of the best on the call, so we have fewer candidates to nominate. Juan de Dios named Moshe Ben-Akiva, Michel Bierlaire, David Hensher, Hani Mahmassani, and Kenneth Train from his own area. Further, he added Huw Williams, Daniel McFadden and David Hensher as those who significantly changed the field. Sergio concurs with those names recalling as well that Hani Mahmassanieven made his views known through an editorial of the New York Times. Further, he added to his list Chandra Bhat who significantly contributed to the econometric field for deriving tractable modelling specifications for the utility function. They both nominated David Hensher as a great candidate for my interview for the next series, especially as Sergio commented that David is a workaholic who responds to your email in five minutes regardless of the time zone the email is sent from.
If David accepts, I will come back with another article on the oral history of travel behaviour with Prof Hensher.