Conceptual Framework

This chapter contains a review on literature for crucial factors and their possible connections to transport diversity. The review ended in the construction of a conceptual framework of transport diversity. The fundamental of transport diversity fits both the concept of quality of life and sustainability in terms of the transport needs. Accordingly, the method used here to assess transport diversity considers the balance between sustainable development and quality of life objectives through consensus among stakeholders, government, and experts.

By setting goal and threshold values, as well as measuring progress towards targets, the framework presented in this study effectively assesses sustainability and quality of life.

Stakeholder needs are determined based on criteria of sustainability as well as quality of life. The emerging consensus is that sustainable transport systems should efficiently provide users with equitable and safe access to basic needs effectively, stimulate economic development, and not cause environmental harm (Pope et al., 2004; Jeon et al., 2006).

Sustainability and quality of life have recently become key planning objectives. Items widely considered in measuring sustainability and quality of life in relation to transport system include social justice, accessibility, safety, universal design, economic health, environmental quality etc. (McMahon, 2002; Pope et al., 2004; Jeon et al., 2006; Ness et al., 2007).

Improving the sustainability and quality of life with regard to transportation requires the support of transport diversity. The conceptual framework used to assess transport diversity for promoting sustainability and quality of life is shown in Figure 2-1 based on the references above. Figure 2-1 shows the stakeholders affecting or affected by subsystems, such as roads, MRT, parking and pedestrian lanes, are. Since transportation needs prevail over those of daily life including diverse socio-economic activities, the constitution of diversity indicates different needs for daily activities based on quality of life.

2.4.1 Economic Efficiency

The construct of economic efficiency is composed of mobility, economic health, and

reliability. Mobility refers to the efficiency of vehicle movements through the road system.

Moreover, mobility describes individual ease of movement (Levine and Garb, 2002; Levinson, 2003). As a result, satisfying the user need for mobility refers to developing the capability to overcome spatial resistance. Besides, both short-term and long-term cost efficiency should be considered in the construct of economic health. Stakeholder needs in this construct include robust public funding, economic growth, technical research and development, and the revenue of operators (McMahon, 2002; Pope et al., 2004; Topolski et al., 2004; Loo and Chow, 2006;

Jeon et al., 2006). Furthermore, reliability describes the consistent, stable and standard outcomes when the experience is repeated under the same conditions. Sanchez-Silva et al.

(2005) addressed the fact that a reliable transport system should provide a stable level of service. Therefore, the key factor influencing needs satisfaction with regard to reliability thus represents whether the extraneous travel time and expenses are invested.

FIGURE 2-1 Conceptual framework 2.4.2 Social Equity

Social equity issues in transportation involve equitable accessibility to major socio-economic centers and equitable level of safety (Jeon et al., 2006). Safety is defined as minimizing risk of hurt, injury, or loss. Traffic accidents are a major socio-economic problem, accounting for millions of fatalities and injuries, as well as billions of dollars of economic losses worldwide. Safety thus is an important criterion in social equity with regard to

(McMahon, 2002; van Kamp et al., 2003; Pope et al., 2004; Steg and Gifford, 2005; Ness et al., 2007). To achieve the need of safety, planners should consider methods of decreasing the traffic accidents and mitigating associated casualties. Additionally, accessibility is utilized to evaluate network development in transportation planning and to measure the potential of regional economic performance in urban planning. In fact, Martellato et al. (1998) demonstrated that accessibility refers to potential opportunities with regard to the interactions among the urban spatial patterns. Levine and Garb (2002) measured accessibility using the ease of interactions between network nodes. Besides, accessibility represents the connection between origins and destinations or between activities (Wachs and Koenig, 1979).

Additionally, accessibility indicates differences in attraction between activities (Burns, 1979).

Moreover, a poverty gap caused by income level and distribution leads to issues of affordability to support socio-economic activities (van Kamp et al., 2003; Steg and Gifford, 2005; Jeon et al., 2006; Loo and Chow, 2006; Ness et al., 2007). Likewise, de Vasconcellos (2005) addressed that the problem of low-income users paying the highest proportion relative to disposable income to make essential trips of any group of public transport users.

Consumption of daily essentials may have to be reduced in the event of transportation becoming unaffordable. Quality of life thus is negatively affected. Therefore, ensuring the affordability of basic trips is necessary for achieving an equitable society. Besides, universal design, otherwise known as barrier-free design, relates to infrastructure and services satisfying the basic needs of vulnerable groups, such as the handicapped, disabled, or elderly users (Loo and Chow, 2006). Furthermore, level of universal design could improve the safety, comfort, and convenience of transportation systems. As a result, the level of universal design should be the critical item in constructing social equity.

2.4.3 Environmental Quality

Governments have traditionally constructed extensive transport infrastructure to enhance transportation efficiency. Motor-vehicle emissions have contributed to the greenhouse effect and ozone hole, and consequently threatened the very ecological system upon which human life depends (OECD, 2001). Emissions also influence health and quality of life. Past research on environmental quality focused on negative externalities, like emissions, noise, waste, water pollution, and habitat destruction (McMahon, 2002; van Kamp et al., 2003; Pope et al., 2004;

Steg and Gifford, 2005; Jeon et al., 2006; Soltani and Allan, 2006; Ness et al., 2007). In response to such research, transportation policies in developed countries have changed during recent years to mitigate adverse environmental impacts. Moreover, excessive use of resources, especially of non-renewable resources, should also be considered in relation to environmental quality (McMahon, 2002; van Kamp et al., 2003; Pope et al., 2004; Steg and Gifford, 2005;

Loo and Chow, 2006; Ness et al., 2007). As a result, the development of green energy and energy-saving vehicles offer means of addressing concerns in this area.

Accordingly, the proposed transport diversity framework represents a long-term planning viewpoint for improving sustainability and quality of life. Nine criteria referring to transportation needs based on transport diversity, such as mobility, economic health, reliability, safety, accessibility, affordability, level of universal design, externality and resource over-utilization, with distinct levels of expected and threshold values for different stakeholder groups are derived from previous literatures. For example, the threshold value of low-income users to deficiently support their basic travel needs might significantly differ from the threshold values of general users. In fact, the improvements of transportation infrastructures and services to assist specific users in achieving their basic needs levels would not negatively impact the perceptions of general users in their trips.

In urban transportation system, an individual belongs to various stakeholder groups in the different space or time. For instance, from the trip chain perspective, an individual utilizing seamless intermodal system might play several roles in the trip. The individual indicates one of residents (non-user) before starting his/her trips, a private vehicle and transit user in park and ride situation, as well as a pedestrian after leaving transit system to the destination. In order to clarify the determinations of following analyses, the criteria identifying the priorities of classifications of stakeholder group are described in Figure 2-2.

FIGURE 2-2 Classification of stakeholder group

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The purpose of this chapter is to introduce the methodologies applied in this study. An optimal indicator system for transport diversity is determined in this chapter. Such a system should identify stakeholder needs and determine appropriate indicators that reflect those needs via the questionnaires and professional information. Section 3.1 discusses the related indicators referring to stakeholder needs based on the determination. A hybrid system simulation method for examining causality in transportation system is presented in Section 3.2. The mathematical programming for optimizing resource allocation within transport diversity is proposed in Section 3.3.