458
1,568.41
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Recent PublicationsView all

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    ABSTRACT: Tour or trip chain based travel analysis has been a feature of transportation research for several decades, but has largely been the preserve of developed countries. Furthermore, the important associations between urban form and trip-chaining behaviour have received little attention. Based on detailed land use data and an activity dairy survey for workers in Beijing, China, this paper investigates how socio-demographic attributes of households, individuals and urban form characteristics at both residence and workplace, correlate with the tour-based travel decision process. We focus on tour frequency, tour scheduling (type and order of stops made) and tour interdependence mechanisms. Empirical results show that socio-demographic attributes and commuting time strongly correlate with tour decisions, but that there is no significant gender difference in tour frequency, as seen in developed countries, although women tend to make more stops within a tour. Urban form characteristics at home and at workplace are significantly associated with tour frequency, but differ with respect to tour complexity. For example, higher residential density is associated with more home-based tours with fewer stops, while mixed land use at workplaces having higher density and accessibility is associated with more stops within one work tour, or a more complex tour pattern. The research also reveals, for the first time, a tour interdependence effect for workers who undertake multiple tours.
    No preview · Article · Jul 2014 · Habitat International
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    ABSTRACT: Developing low carbon cities is a key goal of 21st century planning, and one that can be supported by a better understanding of the factors that shape travel behaviour, and resulting carbon emissions. Understanding travel based carbon emissions in mega-cities is vital, but city size and often a lack of required data, limits the ability to apply linked land use, transport and tactical transport models to investigate the impact of policy and planning interventions on travel and emissions. Here, we adopt an alternative approach, through the development of a static spatial microsimulation of people’s daily travel behaviour. Using Beijing as a case study, we first derive complete activity-travel records for 1026 residents from an activity diary survey. Then, using the 2000 population census data at the sub-district level, we apply a simulated annealing algorithm to create a synthetic population at fine spatial scale for Beijing and spatially simulate the population’s daily travel, including trip distance and mode choice at the sub-district scale. Finally, we estimate transport CO2 emission from daily urban travel at the disaggregate level in urban Beijing.
    No preview · Article · May 2014 · Computers Environment and Urban Systems
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    ABSTRACT: The evolution in number, area and volume of ice-marginal lakes in western Greenland is very poorly documented or understood. It is important to understand ice-marginal lake evolution because they provide an element of meltwater retention, affect ice-margin character and behaviour, and potentially glacier dynamics. This study uses repeat satellite imagery acquired between 1987 and 2010 to reveal a net 44 % (± 6.5 %) increase in the number of lakes, a net 20 % (± 6.5 %) expansion in total lake surface area and an increase of 12% (± 3.3 %) in the estimated volume of meltwater retained along a 1300 km length of the ice margin in western Greenland. Whilst ~ 12 % (± 1.6 %) of the ice margin holds lakes at any one time there is considerable complexity in lake evolution; many lakes have coalesced, drained partially or fully, or become detached from the ice margin. The total lake volume equates to 144 % of the annual runoff combined from Gothab and Jakobshavn hydrological catchments. The rate of increase in meltwater retention between 1987 and 2010 was similar to the rate of increase in ice sheet surface runoff over the same time period. If the study region is representative of the whole Greenland ice sheet margin then as a first-order estimate ~ 5 % of the increased runoff over the last 25 years has been intercepted enroute to the oceans by the increased ice-marginal lake capacity. Interactions between these ice-marginal lakes, the western Greenland ice sheet and climate should be determined to provide insight into future land-terminating ice-marginal conditions, runoff retention and meltwater and sediment fluxes to the oceans.
    Full-text · Article · May 2014 · Global and Planetary Change
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