Shifting based on this approach include dollars

Shifting Trends From Mobility to Accessibility and Evaluation of Accessibility based Measures – A Review and Comparative Case Study Bincy Mariam Koshy, UIN – 663340959 The mobility – based perspective has been dominating the transportation world and is also prominent among the general public. Common indicators based on this approach include dollars wasted while waiting in traffic and Level of Service (USDOT). Transportat ion engineers, planners and the public view ‘rapid movement’ as the ultimate success. However, this perspective has its drawbacks – movement is not the desired outcome by people rather interaction with people and places they want to engage with at destinat ions.

Thus, speed is not imperative and significant. Accessibility – based model includes measuring the level of interaction with people and places; this implies that at lower speeds, high interactions are possible in nearby destinations. Accessibility is defined as the ‘potential of opportunities for interaction’ (Hansen) or the ‘ease of reaching places’ (Cervero) while mobility is defined as the ‘ease of movement’. Accessibility is used as an evaluation criterion and is a function of both land – use patt erns and performance of transport systems. One predominantly useful feature of accessibility is its ability to pinpoint areas or groups that are underprovided and hence influences plans and sometimes only requires spatial reallocation of resources. But the debate on whether accessibility or mobility should be the objective in transportation planning is still ongoing despite many advantages of accessibility -based evaluation. A shift from mobility to accessibility is crucial for improving transportation syste ms as it is the primary criterion by which transportation policy is evaluated.

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The demand for transportation is a derived demand – this demand is due to the need for people to reach destinations which implies that people do not travel for the pleasure of m otion but to reach destinations and this derived nature yields that accessibility is the service provided by mobility. Hence the shift from mobility to accessibility is required to be consistent with the consensus that the demand for transportation is deri ved and the ultimate goal is to reach destinations. This is why the research on shifting to accessibility -based evaluations is crucial in the transportation world. So far, the need for a shift from mobility to accessibility has been discussed and is yet t o be discussed further in detail. Mobility, proximity and connectivity are different means of attaining accessibility. But mobility and proximity exist in tension with one another and therefore exert conflicting influences on accessibility as they have a n egative relationship.

Therefore, mobility and proximity are means of attaining an end, accessibility, which is why it is essential to evaluate the components, mobility and proximity as it directly influences accessibility. In order to evaluate accessibili ty, two metropolitan regions, namely Washington DC and San Francisco are chosen. The effects of mobility and proximity are analysed separately to understand accessibility -based measures. While San Francisco has greater accessibility due to high speed roadw ays, central Washington has closer proximity advantages. This comparativestudy will also help us better understand why the shift from mobility to accessibility is important and strategies to enhance accessibility in the context will be discussed.

Summary of Work This pa per will help us investigate few questions: • Q) What caused the shift from mobility to accessibility based on impacts of mobility -based evaluations? (Done) • Q) What are the obstacles to accessibility -based evaluations and what approaches have been adopted to overc ome it? (In the process of completion) • Q) What are the effects of proximity and mobility on acce ssibility in different contexts? (To be done) So far a detailed study has been conducted on the reason for shift from mobility to accessibility which helps answer the first question in this paper. Follow ing is a summary of the explanation. Importance and Reaso n for Shifting Trends – From Mobilit y to Accessib ility The transp ortation world has been experiencing a shift in trends from traffic – based analysis to mobility – oriented analysis to accessibility – based analysis. These concepts are all related in such a way that traffic is a subset of mobility and mo bility is a subset of accessibility.

(Litman 2013) Fig 1 A huge dilemma on vehicle and driving policies revolved around whether mobility or accessib ility should be enhanc ed. Should policies fulfil what the public wants which is increased driving by accommodating growing levels of vehicle travel or should these policies focus on limiting driving so as to reduce environmental impacts and other costs? The former policy that is under consideration is far more politically palatable but is becoming increasingly unaffordable. The latter implies reversing tr end s and going against American tr aditions of freedom of movement. So the pract ical approach is to improve vehicle and fuel te chnologies tha t will reduce e nvironmental impacts without limiting driving but this will lead to increased driving that will surpass capacity in the future. Another ongoing problem is that a significant AccessiblityPerspectiveMobility PerspiectiveTraffic Perspectivepart of the population cannot drive and do not have acc ess to a car due to income, age and ability issues.

An alternative approach that is increasingly attaining support is reducing driving needs by bringing activities closer to home and improving transit , biking and walking facilities by enhancing accessibility . This approach forms the basis for the shift from mobility to accessibility through road building. Scholars argue that accessibility metrics reflect the purpose of transportation best – to reach destinations rather than t o be in motion which is what mobi lity metrics is mainly focused on. Accessib ility metrics also involves mobility and proximity which is an advantage as it widens the scope for detailed analysis, as seen in fig 1, mobility is a subset of accessibility.

Acces sibility – based planning offers a wide range of solutions to transportation problems and also changes how we think – this shift changes what we consider the systems ‘ center – traffic – based planning places a utomobiles at the center w hile accessibility – based planning places people at the center of the transportation system. Planning practices su ch as evaluations based on travel speed and distance which favour faster modes over slower modes, travel statistics that ofte n undercount and undervalue non -motorized modes of transportation by ignoring short trips , children ‘s travel etc., recognition of benefits of increased vehicle traffic volumes and speeds and overlooking walkability and land use accessibility result in decisions that increase mobility but reduce accessibility but do not provide optimal solutions. They are not detail oriented leading to distortion and skewed results which do not provide accurate and up to date information. Differ ent planning issues require differen t methods to account for users, mod es, perspectives etc. Accessib ility – based analysis takes into consideration all these factor s and offers a range of possible solutions to transport p roblems.

Example 1 – Neighborho od planning requires more walkability analysis while regional planning requires more facilities analysis like, transit, rail and automobi le analysis. Example 2 – Consider a school experiencing congestion, traffic an parking problems. Traffic – based analysis would suggest expansion of road and parking facilit ies, mobility – based analysis wou ld suggest improving school bus facilities while accessibility – based analysis would consider alternative factors and suggest walking an d cycling impro vements and provide incentives to encourage students and staff to reduce vehicular tr ips and also try to reduce dista nce between homes and schools.

These measures are cost effective a s they consider ben efits and costs. Obstacles to Accessibility – Based Evaluations Some of the obstacles are – • Theoretical soundn ess (Weakness of tools) • Communication • Political c hallenges • Local land use control • Lack of constituency Work To Be DoneThe next sect ion will deal with how the obstacles of accessibility – based evaluations can be overcome with a detailed explanation of each obstacle. The final question that focuses on effects of mobility and proximity on accessibili ty in different contexts will be explained by referring to a case study on evaluating accessibility in two regions – San Francisco and Washington D.C. by analysing the effects of mobility and proximity separately on accessibility – based eva luations. Expected findings include – • Central Washi ngton D.C. is a high accessibility zone but due to land use restrictions there are constraints on population thus limiting the i mpact of accessibility zones on accessibility .

(Accessibility zones ensure that significant shares of population have the opportunity to reside in zones such that facilities are accessible equally) • Only 5% of Washington ‘s populat ion lived in the most accessible zones as compared to 9% for San Francisco • Transit facilities are better in Washington D.C. in comparison to San Francisco as it offers large number of people with the opportunity to live in high – accessibility to transit zones • Mobility outweighs proximity in its effects on accessibility in San Francisco due to high speed road s while the case is the rever se in Washington D.C. However, accessibility to destinations is higher in San Francisco as the effects of mobility positively influencing accessibility is higher than the positive effects of proximity in Washington D.C. The data for comparative studies is obtained from US Census Bureau, US Department of transportation database, Federal Transit Administration and National Transit Database. References Geneviève Boisjoly, A.

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