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| 2. |
- Zhao, Xiaoyun, et al.
(författare)
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An Evaluation of the Reliability of GPS-Based Transportation Data
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- GPS-based data are becoming a cornerstone for real-time transportation applications. Tracking data of vehicles from GPS receivers are however susceptible to measurement errors. The assessment of the reliability of data from GPS receiver is a neglected issue, especially in a real road network setting and in the phase after data transfer but before information identification. An evaluation method is outlined and carried out by conducting a randomized experiment. We assess the reliability of GPS-based transportation data on geographical position, speed, and elevation from three varied receivers GlobalSat BT-338X, Magellan SporTrak Pro and smart phone for three transportation modes: bicycle, car, and bus. The positional error ranging from 0158 meters, and 74% to 100% with an error within 5 meters depending on the transportation mode and route, there is also a non-negligible risk for aberrant positioning. Speed is slightly underestimated or overestimated with errors around 5km/h except for SporTrak Pro which had an error
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| 3. |
- Carling, Kenneth, et al.
(författare)
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A compelling argument for the gravity p-median model
- 2013
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Ingår i: European Journal of Operational Research. - : Elsevier. - 0377-2217 .- 1872-6860. ; 226:3, s. 658-660
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Tidskriftsartikel (refereegranskat)abstract
- The p-median model is used to locate P facilities to serve a geographically distributed population. Conventionally, it is assumed that the population always travels to the nearest facility. Drezner and Drezner (2006, 2007) provide three arguments on why this assumption might be incorrect, and they introduce the extended gravity p-median model to relax the assumption. We favour the gravity p-median model, but we note that in an applied setting, the three arguments are incomplete. In this communication, we point at the existence of a fourth compelling argument for the gravity p-median model.
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| 4. |
- Carling, Kenneth, et al.
(författare)
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An empirical test of the gravity p-median model
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A customer is presumed to gravitate to a facility by the distance to it and the attractiveness of it. However regarding the location of the facility, the presumption is that the customer opts for the shortest route to the nearest facility.This paradox was recently solved by the introduction of the gravity p-median model. The model is yet to be implemented and tested empirically. We implemented the model in an empirical problem of locating locksmiths, vehicle inspections, and retail stores ofv ehicle spare-parts, and we compared the solutions with those of the p-median model. We found the gravity p-median model to be of limited use for the problem of locating facilities as it either gives solutions similar to the p-median model, or it gives unstable solutions due to a non-concave objective function.
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| 5. |
- Carling, Kenneth, et al.
(författare)
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Measuring CO2 emissions induced by online and brick-and-mortar retailing
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We develop a method for empirically measuring the difference in carbon footprint between traditional and online retailing (“e-tailing”) from entry point to a geographical area to consumer residence. The method only requires data on the locations of brick-and-mortar stores, online delivery points, and residences of the region’s population, and on the goods transportation networks in the studied region. Such data are readily available in most countries, so the method is not country or region specific. The method has been evaluated using data from the Dalecarlia region in Sweden, and is shown to be robust to all assumptions made. In our empirical example, the results indicate that the average distance from consumer residence to a brick-and-mortar retailer is 48.54 km in the studied region, while the average distance to an online delivery point is 6.7 km. The results also indicate that e-tailing increases the average distance traveled from the regional entry point to the delivery point from 47.15 km for a brick-and-mortar store to 122.75 km for the online delivery points. However, as professional carriers transport the products in bulk to stores or online delivery points, which is more efficient than consumers’ transporting the products to their residences, the results indicate that consumers switching from traditional to e-tailing on average reduce their CO2 footprints by 84% when buying standard consumer electronics products.
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| 6. |
- Carling, Kenneth, et al.
(författare)
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Measuring transport related CO2 emissions induced by online and brick-and-mortar retailing
- 2015
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Ingår i: Transportation Research Part D. - : Elsevier BV. - 1361-9209 .- 1879-2340. ; 40, s. 28-42
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Tidskriftsartikel (refereegranskat)abstract
- We develop a method for empirically measuring the difference in transport related carbon footprint between traditional and online retailing (“e-tailing”) from entry point to a geographical area to consumer residence. The method only requires data on the locations of brick-and-mortar stores, online delivery points, and residences of the region’s population, and on the goods transportation networks in the studied region. Such data are readily available in most countries. The method has been evaluated using data from the Dalecarlia region in Sweden, and is shown to be robust to all assumptions made. In our empirical example, the results indicate that the average distance from consumer residence to a brick-and-mortar retailer is 48.54 km in the studied region, while the average distance to an online delivery point is 6.7 km. The results also indicate that e-tailing increases the average distance traveled from the regional entry point to the delivery point from 47.15 km for a brick-and-mortar store to 122.75 km for the online delivery points. However, as professional carriers transport the products in bulk to stores or online delivery points, which is more efficient than consumers’ transporting the products to their residences, the results indicate that consumers switching from traditional to e-tailing on average reduce their transport CO2 footprints by 84% when buying standard consumer electronics products.
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| 7. |
- Carling, Kenneth, et al.
(författare)
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Out-of-town shopping and its induced CO2-emissions
- 2013
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Ingår i: Journal of Retailing and Consumer Services. - Borlänge : Elsevier. - 0969-6989 .- 1873-1384. ; 20:4, s. 382-388
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Tidskriftsartikel (refereegranskat)abstract
- Planning policies in several European countries have aimed at hindering the expansion of out-of-town shopping centers. One argument for this is concern for the increase in transport and a resulting increase in environmental externalities such as CO2-emissions. This concern is weakly founded in science as few studies have attempted to measure CO2-emissions of shopping trips as a function of the location of the shopping centers. In this paper we conduct a counter-factual analysis comparing downtown, edge-of-town and out-of-town shopping. In this comparison we use GPS to track 250 consumers over a time-span of two months in a Swedish region. The GPS-data enters the Oguchi’s formula to obtain shopping trip-specific CO2-emissions. We find that consumers’ out-of-town shopping would generate an excess of 60 per cent CO2-emissions whereas downtown and edge-of-town shopping centers are comparable.
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| 8. |
- Carling, Kenneth, et al.
(författare)
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Testing the gravity p-median model empirically
- 2015
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Ingår i: Operations Research Perspectives. - : Elsevier. - 2214-7160. ; 2:124
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Tidskriftsartikel (refereegranskat)abstract
- Regarding the location of a facility, the presumption in the widely used p-median model is that the customer opts for the shortest route to the nearest facility. However, this assumption is problematic on free markets since the customer is presumed to gravitate to a facility by the distance to and the attractiveness of it. The recently introduced gravity p-median model offers an extension to the p-median model that account for this. The model is therefore potentially interesting, although it has not yet been implemented and tested empirically. In this paper, we have implemented the model in an empirical problem of locating vehicle inspections, locksmiths, and retail stores of vehicle spare-parts for the purpose of investigating its superiority to the p-median model. We found, however, the gravity p-median model to be of limited use for the problem of locating facilities as it either gives solutions similar to the p-median model, or it gives unstable solutions due to a non-concave objective function.
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| 9. |
- Håkansson, Johan, et al.
(författare)
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Is the spatial scope of agglomeration economies on wages the same across the wage earnings distribution?
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We investigate the spatial scope of employment density across the wage distribution within four distance bands around each individual’s place of work. Observable and unobservable individual and workplace characteristics are controlled for. Remaining endogeneity in the wage model framework is assessed with an IV approach. Results indicate a positive effect of employment density on wages within 5 kilometres. The effect is negative beyond 50 kilometres. The spatial scope of employment density is larger at the higher end of the wage distribution but the effect closest to the establishment seems larger at the lower end of the wage distribution.
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| 10. |
- Håkansson, Johan, 1966-, et al.
(författare)
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Regionförstorande effekter av höghastighetståg : visualisering av SAMPERS-resultat
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hur kan den geografiska storleken på individers arbetsmarknad öka i olika områden om man inför nya höghastighetsbanor för tåg? Den här studien syftar till att visualisera den potentiellt ökade storleken på arbetsmarknaderna i områden där det finns tankar om att investera i banor för höghastighetståg i Sverige. I studien har forskarna använt prognoser över antal arbetsresande med kollektivt färdmedel, som tagits fram med det nationella prognossystemet SAMPERS, för tre olika scenarier. Två av dem inkluderar investeringar i höghastighetsbanor men de skiljer sig något åt i termer av var banorna skulle byggas. Det tredje scenariot utgörs av ett jämförelsealternativ utan banor för höghastighetståg. Analysen tyder på att de största effekterna av höghastighetsbanor ligger i Västsverige, närmare bestämt i stråket från Göteborg via Borås bort mot Jönköping och i området runt Linköping och Norrköping. Men i allmänhet tyder resultaten från prognoserna på relativt små ökningar av potentialen
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