Sekhar Somenahalli

Using GIS to Identify Pedestrian-Vehicle Crash Hot Spots and Unsafe Bus Stops

This paper presents a GIS approach based on spatial autocorrelation analysis of pedestrian-vehicle crash data for identification and ranking of unsafe bus stops. Instead of crash counts, severity indices are used for analysis and ranking. Morans I statistic is employed to examine spatial patterns of pedestrian-vehicle crash data. Getis-Ord Gi* statistic is used to identify the clustering of low and high index values and to generate a pedestrian-vehicle crash hot spots map. As recent studies have shown strong correlations between pedestrian-vehicle crashes and transit access, especially bus stops, bus stops in pedestrian-vehicle crash hot spots are then selected and ranked based on the severity of pedestrian-vehicle crashes in their vicinities. The proposed approach is evaluated using 13 years (1996–2008) of pedestrian-vehicle crash data for the Adelaide metropolitan area. Results show that the approach is efficient and reliable in identifying pedestrian-vehicle crash hot spots and ranking unsafe bus stops.

Impacts of Property Accessibility and Neighborhood Built Environment on Single-Unit and Multiunit Residential Property Values

Recent consumer surveys and empirical studies suggest linkages between property accessibility, neighborhood built environment, and residential property values. This paper describes a comprehensive study that was undertaken to understand the impacts of property accessibility, neighborhood built environment, and other contributing factors on single-unit and multiunit residential property values. The study used a sample of more than 4,500 single-unit and 2,300 multiunit residential properties collected in more than 1,800 neighborhoods of Adelaide, Australia. Hedonic house price models were applied to study the similarities and dissimilarities of the impacts of types of property accessibility (property accessibility to retail locations and to social and recreational locations by walking, public transit, and automobile), neighborhood built environment (land use mix, residential density, and intersection density), and other contributing factors (physical attributes of the property, social and economic characteristics of the neighborhood, and public school district quality) on single-unit and multiunit residential property values. The model results suggest that planners should consider land use mix, new social and recreational locations, intersection density, and public transit locations in designing and implementing neighborhood development strategies. The results also indicate that investors should consider the following in developing property investment strategies: the property’s physical condition, its proximity to retail, social, and recreational locations, school district quality, neighborhood development intensity, and residents’ preferred residential property features. Further, the impacts of various contributing factors on single-unit and multiunit residential property values can be used to aid planners in neighborhood design and to assist investors in making more informed residential property investment decisions.

Use of shadow for enhancing mapping of perennial desert plants from high-spatial resolution multispectral and panchromatic satellite imagery

Abstract. Satellite remote-sensing techniques face challenges in extracting vegetation-cover information in desert environments. The limitations in detection are attributed to three major factors: (1) soil background effect, (2) distribution and structure of perennial desert vegetation, and (3) tradeoff between spatial and spectral resolutions of the satellite sensor. In this study, a modified vegetation shadow model (VSM-2) is proposed, which utilizes vegetation shadow as a contextual classifier to counter the limiting factors. Pleiades high spatial resolution, multispectral (2 m), and panchromatic (0.5 m) images were utilized to map small and scattered perennial arid shrubs and trees. We investigated the VSM-2 method in addition to conventional techniques, such as vegetation indices and prebuilt object-based image analysis. The success of each approach was evaluated using a root sum square error metric, which incorporated field data as control and three error metrics related to commission, omission, and percent cover. Results of the VSM-2 revealed significant improvements in perennial vegetation cover and distribution accuracy compared with the other techniques and its predecessor VSM-1. Findings demonstrated that the VSM-2 approach, using high-spatial resolution imagery, can be employed to provide a more accurate representation of perennial arid vegetation and, consequently, should be considered in assessments of desertification.

High-spatial resolution multispectral and panchromatic satellite imagery for mapping perennial desert plants

The use of remote sensing techniques to extract vegetation cover information for the assessment and monitoring of land degradation in arid environments has gained increased interest in recent years. However, such a task can be challenging, especially for medium-spatial resolution satellite sensors, due to soil background effects and the distribution and structure of perennial desert vegetation. In this study, we utilised Pleiades high-spatial resolution, multispectral (2m) and panchromatic (0.5m) imagery and focused on mapping small shrubs and low-lying trees using three classification techniques: 1) vegetation indices (VI) threshold analysis, 2) pre-built object-oriented image analysis (OBIA), and 3) a developed vegetation shadow model (VSM). We evaluated the success of each approach using a root of the sum of the squares (RSS) metric, which incorporated field data as control and three error metrics relating to commission, omission, and percent cover. Results showed that optimum VI performers returned good vegetation cover estimates at certain thresholds, but failed to accurately map the distribution of the desert plants. Using the pre-built IMAGINE Objective OBIA approach, we improved the vegetation distribution mapping accuracy, but this came at the cost of over classification, similar to results of lowering VI thresholds. We further introduced the VSM which takes into account shadow for further refining vegetation cover classification derived from VI. The results showed significant improvements in vegetation cover and distribution accuracy compared to the other techniques. We argue that the VSM approach using high-spatial resolution imagery provides a more accurate representation of desert landscape vegetation and should be considered in assessments of desertification.

Accessible transportation and mobility issues of elderly — how does Australia compare with Japan?

Accessible transportation is a key aspect of independent living. As the impact of population ageing on future transport systems is expected to be increasingly felt over the next few decades in a number of countries, including Australia and Japan, it is logical to recognise the importance of formulating appropriate transport policies in ageing societies. However, few studies in Australia have focussed on this issue as most of them have been devoted to the physical dimensions of health. This paper is based on a recent survey of older South Australians and a series of in-depth discussions conducted with key stakeholders both in Australia and Japan, conducted by the principal author. This paper highlights the accessible transportation and mobility issues in Australia’s ageing society by shedding light on some of the important policies and laws prevailing in Japan, which have already reached the proportion of the older population that Australia is projected to be 10 years from now. Our findings would provide answers and new approaches into the challenges from a policy and legislative perspective to help formulate recommendations for the stakeholders.

The Methodology Development of Railway Level Crossing Safety Systems – South Australia Case Study

This paper describes how railway level crossing accident is one of the major contributing factors of railway related fatalities in many countries. Even though railway level crossing accidents can be considered as a rare event, the impact is often severe. In Australia, safety issues at railway level crossing are not very serious relative to those of developing countries. However, railway level crossing accidents have continuously become a concern in railway industries in especially when it involved fatalities. This paper presents a methodological development proposed for railway level crossing safety systems and South Australia’s situation is used as a testing case. Due to the complex nature of railway level crossing safety systems; Petri Nets approach will be applied in assisting the development of a meaningful evaluation model. The components of basic concept of safety engineering; engineering infrastructure, level crossing surrounding environment and human factors will also be considered in the model.

Investigating Theoretical Development for Integrated Transport and Land Use Modelling Systems

A lack of integration in transport and land use modelling systems has been a major handicap for strategic planning operations in many cities; hence there is a need for a more interactive, flexible and accurate system that can meet various sustainable planning objectives. This chapter discusses the theoretical development of the relationship between transport and land use models. Previous practices show that a combination of bid-rent theory and random utility theory would provide mutual benefits for transport and land use models. Bid-rent models provide the location of activities with households and firms, which helps the estimation of random utility mode choice models in transport models. In turn, the output of transport models can be used to measure accessibility in land use models. This chapter also highlights the importance of using data base manager to include Revealed Preference data, Stated Preference data and Bluetooth data. Two current practices in Adelaide and Perth are analyzed. The application of a combined bid-rent theory and utility function theory are proposed for future empirical studies.