Multimodal accessibility modeling from coarse transportation networks in Africa

Abstract

Accessibility is a key driving factor for economic development, social welfare, resources management, and land use planning. In many studies, modeling accessibility relies on proxy variables such as estimated travel time to selected destinations. In developing countries, estimating the travel time is hindered by scarce information about the transportation network, making it necessary to take into account off-network travel coupled with considerations of multimodal options available within the existing network. This research proposes such a hybrid approach that computes the travel time to selected destinations by optimizing together a fully modeled multimodal network and off-network travel. The model was applied in a region around Kisangani located in northeastern Democratic Republic of the Congo. Travel times to Kisangani from the hybrid approach were found to be in close agreement with field-based information (R 2 = 0.98). The developed approach also proved to better support real-world transportation constraints (such as transfer points between travel modes or barriers) than cost-distance-based travel-time modeling. Demonstration results from the hybrid approach highlight the potential for impact assessment of road construction or rehabilitation, development of secondary towns or markets, and for land use planning in general.

Forest cover dynamics of shifting cultivation in the Democratic Republic of Congo: a remote sensing-based assessment for 2000–2010

“…Low rates of deforestation mask the real threats to forests in the DRC, with much higher rates than the national average in heavily populated regions with a strong agricultural sectors and subsistence farming (DeWasseige et al 2012). Landscapes in the DRC remain relatively inaccessible compared to other tropical regions, providing a unique opportunity to avoid future forest deforestation by also employing models to predict future forest loss and degradation, its drivers and impacts (Potapov et al 2008, Bwangoy et al 2010, Defourny et al 2011, Kibambe Lubamba et al 2012. As the country hopefully regains stability in the coming decades, well-informed strategic land use planning will continue to be crucial for sustainable development.…”

“…In many areas existing roads are expanded and connected to improve the transit of goods for livelihood and towards accessible markets (Wilkie et al 2000, Kibambe Lubamba et al 2012. The road between Bwafalinga and Opienge is an example of a transit route expanded during the study period.…”

“…In many cases, observable forest cover loss remains associated with the forest clearing necessary for the shifting cultivation that feeds worker populations involved in the natural resource extraction. Sometimes agricultural clearing follows the development of new transportation and logging roads which are used to access the interior forest and sometimes connect trade routes and villages (Wilkie et al 2000, Russell et al 2011, Kibambe Lubamba et al 2012. These areas can become connected in new rural complex areas.…”

Measuring spatial accessibility to urban services for older adults: an application to healthcare facilities in Milan

“…i refers to the smallest territorial unit, a 50-m-side hexagonal cell [ 37 ]. The use of hexagonal grid (rather than a square one or census track) is recommended for dealing with problems related to the connectivity of different space units and identifying shorter paths for calculating travel distances [ 38 ]. On the supply-side, the land-use component is described by the combination of healthcare structures ( j ) locations and their resources— S j —described, for instance, by the number of working physicians, available beds or surface of buildings (mq) [ 39 ].…”

Multimodal Accessibility to Primary Health Services for the Elderly: A Case Study of Naples, Italy

“…The use of grid frames is crucial for experimental and observational science, as well as for providing the most common framework for spatially explicit models [33]. The hexagonal cell, which is the minimum spatial unit into which the study area is divided, and its sides, may have dimensions previously selected by the user based on the area to be analyzed [34]. In the literature, the use of a hexagonal cell rather than a square is advised for areas that have problems related to the connectivity of different space units and the identification of shorter paths for calculating travel distances [35].…”