Determining the effect of land use characteristics on trip rates in residential areas : (a case of Jaipur)

Abstract

As per census of India 2011, 31% of the total population lives in Cities and Towns of India and constitutes the World’s second largest Urban System. Based on current trends, 50% of the population of the country would be living in Urban Areas by 2060. Quite evidently, the cities and towns of emerging India, are in the midst of fundamental economic restructuring, through the major initiatives of the present Government in the Centre, these cities will play a pivotal role as the centres of economic activity competing with each other to attract global investment, capital and businesses. As a consequence of uncontrolled urbanisation in India, degradation of the quality of life is rampant with numerous underlying issues and its repercussions. These are manifested as e.g., land insecurity, affordable shelter, congestion, traffic fatalities, declining water quality, exorbitant air contamination and the issues of waste disposal. Despite multiple negativities of unplanned urbanisation in India, urbanisation is continual and efforts are needed to aid urbanisation in a sustainable manner. The Tier II cities are competing with the metropolitan cities and they are being successfully upheld by forward-looking state governments. The positive economic development will result in increased urban population, which will further result in increased pressure on city governments in providing infrastructure (like transportation, sanitation, water supply, etc). At present various central and state government schemes are in operation like AMRUT, Smart Cities, Green Urban Mobility Scheme, etc. The importance of transportation in such plans is highlighted in setting provision as well as transportation supply without full consideration on the existing land use and transport interactions. This has resulted in issues of optimal usage of transport, despite, increase in transport infrastructure through new development schemes. Without full consideration of the proposed developments and its effects on transportation systems, such schemes could fail many social and transport objectives. The road infrastructure plays an important role in the socio-economic growth of a city and without a proper understanding of urban development impacts on the transport system, the intent of the such developments which are to bring economic and social benefits could be easily defeated through unanticipated traffic congestion and other negative impacts such as air & noise pollution, vibrations and a degraded quality of life at large. It is well known if new developments are not carefully executed with prior consideration of existing provision and services w.r.t. urban transport systems, they will generate new complexities leading to poor economic returns due to poor speeds, travel delays, air pollution and high fuel consumption leading to higher travel costs and an increase in the total number and severity of accidents. New developments, if not planned properly, pose a great threat to the accessibility and mobility of travellers. In other words, the additional traffic generated from the new urban developments will have an adverse impact on the Level of Service (LOS) of the road network. Therefore, it is essential to conduct a transport assessment during the planning stage of the new development to determine the amount of traffic that will be generated from the new development and to determine, if the existing road network is capable of sustaining the combination of both, the present as well as the new development traffic. If the existing road network is unable to accommodate the development induced traffic, ways of mitigation can be planned based on the results obtained from such transport assessments, when necessary modifying the road geometrics, adding an additional lane, providing roundabout or configuring traffic signal among others that seem appropriate to the local conditions. In many developing countries, including India, it is not viable to do transport assessments for every upcoming development, due to lack of professionals and capital resources. Similarly, there is an absence of mechanisms and procedures to estimate the Gross Floor Area, Floor Space Index, Floor Area Ratio etc. Furthermore, the relationships between the FSI, FAR, and other development control regulations with the available road infrastructure are absent. This is crucial to identify future needs of transport infrastructure in maintaining the same Level of Service (LOS) or better w.r.t proposed developments. Therefore, there are significant gaps in understanding of land use and transport impacts in Indian context specially pertaining to land use types & composition, location proximity to urban centres and transport characteristics. The United States has many versions of Highway Capacity Manual to address these interrelationships. Similar attempts are made many western and eastern counterparts such as Malaysian highway capacity manual, Germany highway capacity manual, etc. In the absence of a comprehensive trip generation manual for Indian cities, transport planner presumes the trips rates either directly from HCM or similar studies conducted elsewhere. Thus, there is a need for estimating trip rates for Indian scenario, which can be used as a reference by transportation and traffic engineering scholars, transport planners, urban planners and other urban management practitioners, during the assessment of the new developments. This can reflect truly, the complex inter-relationships that a diverse county like India poses pertaining to trip generation in a localised manner. There is a further need to develop a mechanism by which Gross Floor Area, Floor Space Index and Population Density can be determined and permitted based on the threshold road infrastructure & its effect on the neighbouring road network at large. Moreover, there is a need to ascertain optimum land use type, scale and composition, which can ascertain the transport supplies in near and -long term. The transport system configuration may suggest in case of inadequate transport supply, the reduction in the total traffic demand in long, medium and short term as well as promotion of non-motorised modes of transport such as walking and cycling. In this study, four residential societies were selected having different socioeconomic characteristics and varying distances from central business district. Surveys were conducted in gated societies to cover the following factors: average income, auto ownership, household size, type of house structure, distance from central business district. Trip characteristics and volume counts were taken at the entrances and on neighbouring road networks (both upstream and downstream of the gated societies). The analyses were based on three types namely Trip Rate Analysis, Cross-Classification and Regression Analysis techniques.  Trip Rate Analysis: Trip Rate Analysis can be said as the easiest of the three where the general procedures are to count the total number of people and/ or vehicle coming in and out of the prescribed area within an allocated time frame. Then these traffic volumes are divided by a variable that make the characteristics of the prescribed area namely the total of parking spaces, gross leasable area, gross floor area, occupancy rate, number of employees and others to obtain the trip attraction rate per any of the used variable. (Uddin, M. M., et al., 2012).  Cross-Classification: It is used to shows the number of trips produce per household with characteristics such as car ownership household size and/ or other variables seems fit. Each element of the table is multiplied by the number of households in the same category, and the product is summed up for all categories in the table to obtain the number of total trips generated in the traffic analysis zone. (Rhee, J., 2003). Cross-Classification takes into account the important elements which are the variables contribute number of trips but the limitation of this method is that there is no method to determine whether the independent variables are truly independent and no statistical test to support the end results.  Regression Analysis: The number of trips is assumed to be linear to the variables used. The variables used can be combination of few independent variables to produce a multiple regression or one independent variable to produce a single regression. Vehicle ownership, household size, gross floor area, number of parking spaces, travel distance and other factors that contribute to the number of trips can be use as the variables. All the variables can be checked for the dependency of each other by using a statistical analysis to ensure a goodness of fit from the available data. The problem with this method is that trip generation is dynamic in nature which means it changes every time and again irrespective to any variables which makes the trips as non-linear. Major findings as obtained from the study are:  This study was able to estimate the trip rates per 100 m2 Gross Floor Area of the gated societies especially in the Indian context. These trip rates provide reasonable estimates of the current transport supply thresholds with respect to the effect of upcoming residential developments.  Furthermore, the relationships between Gross Floor Area (GFA) & Level of Service (LOS) of the neighbouring network were established. These relationships were used to check the sensitivities of the transport infrastructure with respect future proposed developments. These relationships could provide indispensable aid in decision making while performing reverse planning. After careful examination of the effects of new residential developments (expressed in GFA units), the urban local bodies may consider development of only allowable total GFA based on the transportation thresholds at present and in the future.  This study examined the relationships of land use composition with trip rates and trip lengths. The understanding of the obtained relationships can be used to suggest allowable population densities. This would implicate land use planning provisions focusing on reducing the trips that have longer trip lengths. Likewise, such relationships would suggest reduction of the overall travel using private transport. Such land use and transport synergies would provide enormous gains in terms of transport system efficiency, including healthier communities. Such policies would promote the use of nonmotorised transport modes and its full integration into inter-modal and multimodal transport. Such interventions increase propensity to mobility and accessibility, while ensuring environment and ecology of the urban agglomerations of the future.  This study also advocates the need for additional revenues for municipal operations by charging the private developers. These responsibilities could be charged based on need of transport interventions accordingly. These interventions could be as simple as modification of the traffic signal, traffic signal phasing etc. or may involve widening of the existing right of way to accommodate the induced traffic.