«Technical Report Documentation Page 1. Project No. 2. Government Accession No. 3. Recipient's Catalog No. SWUTC/11/161127-1 4. Title and Subtitle 5. ...»
The growing number of dual-earner households raises challenges to the conventional interpretation of individual's commuting behavior, which assumes a single or main earner in a household and the household makes decision on residential location based on the household's housing needs and the single- or main earner's commute. However, the commuting decisions for two workers in a household are interdependent; and a dual earner household would attempt to minimize the overall commuting cost in terms of travel time, money and energy of two partners (Badoe, 2002). In reality, dual-earner households face more complex situations than single earner households in determining residence locations and accepting job offers since they have to make decisions on careers for both partners along with the considerations of family lives (Sultana, 2006). Living near the work place of one partner may cause a longer commute for the other (Hjorthol, 2000; Turner & Niemeier, 1997). In some other cases, journeys to work by couples in a two earner household may be jointly chosen to be longer or shorter due to the household preference of housing and neighborhood amenities (Plaut, 2006). Researchers have also found that dual earner households tend to move less than single worker households (J. N.
van Ommeren, Rietveld, & Nijkamp, 1998). In the situation that the job market in one region cannot satisfy both partners, one partner may choose to commute a long distance in other regions (Green, 1997).
As more women participate in the job market, researchers have paid an increasing attention to the gender difference in commuting behavior. General findings suggest that women remain to bear more house work responsibilities than men, especially in households with children, despite they are playing a more and more important role in the workforce; women usually also receive relatively lower wages and returns to commuting then men. They typically take shorter commute time and distance than men (Clark, Huang, & Withers, 2003; Hjorthol, 2000; Plaut, 2006; Turner & Niemeier, 1997). In addition, women are more likely to use public transportation and have trip chains in the journey to work (Hjorthol, 2000; Rose, 2009). Although women usually dislike long distance commuting, they may attempt to "make a negative into a positive" by using the commuting trip as "a mental shift, contemplation and relaxation" (Blumen, 2000; Lyons & Chatterjee, 2008, p. 194, Rose, 2009).
While most partners in dual earner households are making great efforts to coordinate their work and family life, a "living apart together" (LAT) relationship has also emerged in many dual earner households in a way that the partners do not choose to cohabitate as the traditional family form does. LAT allows the couple to pursue careers in different regions with more employment options while maintaining a desired degree of interdependence (Levin, 2004). The LAT relationship brings women a greater sense of autonomy and leads to a more balanced division of household work. It helps both partners well divide work from leisure and increases the quality of their time together (Holmes, 2009). Not traveling on a daily basis, LAT partners tend to commute in long distances.
2.2. New Information and Communications Technologies
The emergence of LAT relationships benefits from the advance of Information and communications Technologies (ICTs) (Levin, 2004). With ICTs people become connected to each other when they are not physically together. ICTs includes five broad application categories;
they are telecommuting, teleconferencing, teleservices such as teleshopping or telebanking, mobile communications, and electronic message transfer (Mokhtarian, 2002; Salomon, 1986).
These applications could greatly affect people's face-to-face interaction and people's need for travel.
Researchers have long realized the connection between ICTs and transportation (Gold, 1979; I.
Hardill & Green, 2003; Mokhtarian, 1990, 2002; Salomon, 1985, 1986; Walls, Safirova, & Jiang, 2007). The possible effects of ICTs on transportation include (1) substitution, the application of ICTs could reduce people's physical travel; (2) complementary, the application of ICTs could either stimulate people to travel more or could help people make travel more efficiently, and (3) modification, the application of ICTs could change the time when people decide to travel without either reducing or increasing the number or length of trips (Mokhtarian, 2002).
There has not been an agreement on the actual effect of transportation and ICTs. For example, based on several surveys in North America on teleconferencing, Gold (1979) concluded that teleconferencing would not facilitate a reduction in intercity travel in the 1980s, but it could eventually substitute some intercity trips if more ICT systems were provided. In contrast, by examining people's attitudes towards ICTs and travel for different purposes including work, shop and business, Salomon (1985) believed that people's desire of mobility would counterweight the substitution of telecommunication for travel. A more recent nationwide survey conducted in Finland about the impact of telecommuting on commuting distance and frequency showed that the effects varied depending on the actual commuting distance (Helminen & Ristimaki, 2007). In addition, job types could also affect people's choice in telecommuting. Walls et. al. (2007) claimed that jobs in sales, education and training, and architecture and engineering appeared to be more likely to have telecommuters based on a survey in Southern California.
Despite the inclusiveness in the relationship between transportation and ICTs, both telecommunication and travel are believed highly likely to continue to grow in the future.
Telecommunications do permit great flexibilities in making travel decisions such as whether, when, where, and how to travel (Mokhtarian, 2002). In terms of commuting, the option of telecommuting provides people the possibility to work in places other than the office and during the time other than regular working hours. Thus long distance commuting could become more acceptable when people have the choice to work at home for some time or even some days in a week.
While ICTs continue to advance, there are also new technological breakthroughs in passenger transportation technologies, such as higher fuel efficiency cars, electronic cars, and high-speed rail (HSR). HSR is noteworthy as one of the most significant new travel modes. HSR has a speed ranging from more than 100 mph to more than 300 mph. Since the beginning of year 2008, there have been about 10,000km of new HSR lines in operation around the world (Campos & Rus, 2009), most of them were distributed in Europe and East Asia. HSR is regarded as an effective transport mode for linking places that are 100 to 500 miles apart (Leinbach, 2004; Nash, 2003).
Compared to the automobile, HSR has the advantage of being able to move passengers at a much higher speed and enables a far higher throughput of passengers per hour than roads. Compared to the air mode, HSR can free passengers from checking in and going through security screening at airports and is more flexible in expanding capacities than airplane (Nash, 2003). Additionally, HSR are believed to be more environmental friendly than auto and aircraft since it operates mainly on electricity and produces little CO2 emissions. It consumes about 17% and 21% less energy per passenger mile than aircraft or automobile respectively, and is specially designed for noise abatement to reduce negative impacts on sensitive habitats (Ross, 2008; Zaidi, 2007).
The advantages of HSR have attracted many supporters who consider HSR a mode with a great potential to serve the needs of megaregions, in which the typical distance between metropolitans falls in the ideal operating length range of HSR. In turn, HSR could also largely shape the interregional commuting images. For example, if HSR were implemented in the Texas Triangle connecting the four major metro areas at a speed of 430 miles per hour, it would reduce the travel time by more than 70%, enabling people to commute between any pair of cities in the Triangle Area within a reasonable daily commuting time (Zhang, et al., 2007). In such a scenario, both households and companies could enjoy the benefit of being able to access more opportunities and resources in the megaregional environment than those available in individual metropolitan areas.
2.3. New Concept of Arranging Work Time
In recent years, employers have begun to allow employees greater flexibilities in arranging their work times. In this case, employees do not have to follow a set "9-to-5" pattern but can vary the actual time they arrive and leave the office. In 1997, 27.6% of full-time workers, or more than 25 million workers in the US somewhat varied their work hours (Beers, 2000). This flexible work hour arrangement is more common for workers whose work can be conducted efficiently regardless of their start and end times, such as executive, managerial or professional occupations (Beers, 2000). As employees enjoy the flexibility work hours, they tend to work longer when the work time is not fixed (Irene Hardill, 2002). Furthermore, some employers have scaled down office facilities and equipped employees with laptops and ICT equipment to let them work from home, during travel or any places possible in order to reduce real estate costs (I. Hardill & Green, 2003).
Except varying the start and end work time daily, there is another type of work time arrangement different from the traditional work schedule - a compressed workweek (CW). CW allows workers to work fewer days in a week but a longer work day to compensate the hours lost because of the additional free days (Hung, 1996). For employees, CWs result in fewer commuting trips and better utilization of leisure time. Thus CWs are especially attractive for long distance commuters. Actually, some research has claimed that in the US most employees prefer CWs to the standard 5-day workweek (Hung, 1996; Ronen & Primps, 1981; Zhou & Winters, 2008). On the other hand, employers also benefit from CWs. Most US firms that implemented CWs reported increased morale and work efficiency (Hung, 1996).
As people gain more flexibilities in arranging work time and space, the day-to-day variability in commuting and work behavior could become enlarged. Then the "typical work day" picture that is used in the current travel demand analysis may not be able to capture the true activities of many workers. For example, a person may vary his or her work arrival time and departure time the first and last day of a week and keep a regular schedule the rest of a week; a person who adapts CWs will actually have a "typical work week" instead of a "typical work day". Thus, the concept of allocating time weekly should be discussed. Researchers have indeed realized the existence of longer than daily cycle of travel activities (Doherty, Miller, Axhausen, & Garling, 2002; Hanson & Huff, 1988; Hirsh, Prashkea, & Ben-Akiva, 1986; Jones & Clarke, 1988).
Generally speaking, one-week time period could capture a proper collection of an individual's different daily patterns (Hanson & Huff, 1988; Hirsh, et al., 1986).
2.4. People's Changing Attitude Towards Travel
Travel has been traditionally deemed as "derived demand". That is, people travel in order to fulfill the need to engage in activities at various locations. For instance, the purpose of commuting is to get to the office and work. However, Mokhtarian & Salomon (2001) challenged this concept and argued that human has the intrinsic to travel and travel itself could be the actual demand. According to them, the positive utility of travel includes "the sensation of speed, the exposure to the environment and movement through that environment, the ability to control movement in a demanding and skillful way, the enjoyment of scenic beauty or other attractions of a route"(p. 699). Sometimes, the desire to travel may encourage people choose a longer route to get to their destination, or even induce the demand for an activity. In their research, Mokhtarian & Salomon conducted a survey with more than 1900 samples in three communities in the San Francisco Bay Area and confirmed the positive utility of travel. More than half of the respondents reported having experience of traveling "just for fun of it" and agreed that journey itself was part of the good thing when traveling somewhere (Mokhtarian & Salomon, 2001).
Not only traveling itself brings enjoyment to people, people can also do many activities while traveling (Lyons & Urry, 2005; Mokhtarian & Salomon, 2001; Ohmori & Harata, 2008). The survey conducted by Mokhtarian & Salomon(2001) found that travel time was not generally considered only as wasted time. Rather, people can do a variety of things on a journey, such as sleeping, reading, listening to music, playing electrical games, and working while riding a bus or a train. The application of ICT further enriches the activities by enabling people to communicate with people in any other places and access the internet using mobile devices. An on board survey in Japan conducted on normal trains and high-grade rains, the "liner trains", which provide larger space and better services and privacy at an extra charge, indicated that people tend to pay more to be able to better utilize travel time on liner trains; the survey also found that passengers were engaging in numerous types of activities on the trains, and some passengers with flexible work hours used the journey as working time(Ohmori & Harata, 2008). Commuting time thus could become productive. In this case, public transportation would be valued higher than driving.
On the other hand, traveling offers people a period of "anti-activities", a period of purely relaxing and thinking, and a mental transaction between origin and destination activities (Lyons & Urry, 2005; Mokhtarian & Salomon, 2001). In term of commuting, some people may prefer the buffer created by the journey and having the time to switch roles from work to family life. Both the activities and the "anti-activities" brought by the commuting time lead some commuters to consider the long trips that "represent the only time for thinking or the chance to catch up on reading or other neglected but important tasks" (Mokhtarian & Salomon, 2001, p. 702).
3. Studies on Long-Distance Commuting (LDC) / Trans-Regional Commute (TRC)