Regional valuation of infrastructure improvements. The case of Swedish road freight

Is it possible to identify regional differences among shippers in their valuation of infrastructure improvements? The question is analysed within a random utility approach where parameters are estimated by a logit model. Data consists of a Swedish stated preference study from 1992. The results indicate that regional differences may exist but a considerable heterogeneity in the empirical material prohibit robust results in some cases. However, regional differences seem to exist when industrial mix, shipping distance and goods values are held constant. Independent of the limitations, the results should render implications to any infrastructure benefit analysis where parameters from spatial averages are used. The results are based on short term decisions and one should recognise that parameters may vary under mid- and long- term.Regional preferences; road transportation; freight demand; stated preference analysis; random utility models; logit model

Estimation of interregional freight flows with a gravity model by OLS estimation, Poisson and neural network specifications

In this paper we compare three different specifications of gravity models for inter regional freight flow prediction. The most used specification with OLS estimation is compared with a model where data are assumed to be Poisson distributed. We also compare these with a Feed Forward Back Propagation Neural Network. Data consists of freight flows between Norwegian counties. The attribute describing the nodes is population and distance in kilometers gives the friction on transport links. Since we here only are interested in inter regional flows all intra regional flows are excluded. Results are also compared with an earlier study by Bergkvist and Westin (1997) were all data were used. Estimations indicate that OLS compared to Poisson and Neural Network specifications will produce worse predictions. However, the question on how to compare performance is not undisputable and of great importance since different measures can produce quite different results, not just in scale but also in ranking. When non-linear models are used the lack of a simple interpretable R-square measure as in linear regression is evident. We therefore use different measures of performance and discuss their pros and cons. Bergkvist E. and Westin L. (1997) Estimation of gravity models by OLS estimation, NLS estimation, Poisson and Neural Network specifications. Submitted to "Analytical advances in Transportation Systems and Spatial Dynamics." Eds. Gastaldi M. and Reggiani A.

The value of time and forecasting of flowsin freight transportation

This paper gives an overview of the current state of research and present own results in some areas regarding cost benefit analysis (CBA) for road infrastructure investments. It deals with the robustness of the estimated average value of time (VOT) currently used in Swedish infrastructure appraisals and also analyses the estimator in the case of different heteroskedastic errors and functional forms. It finallly consider forecasts of road freight flows in cases where information are scarce and may lack precision. Critical questions are how heterogeneity and non-linearities influences forecasts in the freight market. In detail it consdier the following: The impact of VOT for road freight when the origins of transports are taken into account. VOT is found to be dependent on combinations of region, transported distance, industry bransch and if transports are owned or hired. However, available data does not allow for significant values in each category. Altogether the study indicates a VOT spanning from 0 to 732 SEK, which should be compared with the average value of 80 SEK used today. The results also indicate pair-wise differences in VOT between short and long as well as hired and internal transports. The ownership condition is found to have a significant impact on VOT, although current data not gives significant differences between each of the four ownership/distance categories. It is found that further studies should focus on the hypothesis that VOT for short internal freight flows are significantly higher than the average VOT. The traditional logit model is compared with the semi-parametric weighted average density (WAD) estimator. It is found that the performance for the WAD estimator in terms of bias and mean square error is similar to the logit ML estimator for spherical errors in a latent variable specification. Methods for prediction of road freight flows are also investigated. Three traditional gravity model specifications (OLS, NLS, and Poisson regression) are compared with a neural network specification. On a data set of Norwegian inter-regional freight flows it is found that the Poisson model performs best in terms of root mean square error (RMSE) but also that the size of predicted flows is dependent on the method chosen to evaluate available estimation methods. Finally, we integrate freight flow prediction and estimation of VOT in one analysis. Logit models and neural networks with linear and non-linear profit functions are compared. The study indicates that the average VOT may decrease when prediction improves as models are given more non-linear specifications.

Antisemitismens gensvar - En undersökning av judars utsatthet och otrygghet

Denna uppsats undersöker svenska judars utsatthet, trygghet och upplevda risk. Undersökningen har gjorts genom en kombination av kvantitativ och kvalitativ metod. Syftet med uppsatsen är att presentera deskriptiv statistisk dataanalys och att nyansera och få djupare förståelse för denna genom kvalitativa utsagor. Det empiriska materialet har teoretiserats utifrån en kombination av konventionella trygghets- och stigmatiseringsteorier. Vi har funnit att utsatthet för hot och trakasserier bland våra respondenter är väsentligt högre än bland det nationella genomsnittet. Fyra av fem respondenter uppger dessutom att de känner oro inför att bära judiska symboler och ungefär två av fem uppger att de undvikit en religiös tillställning på grund av deras oro. Beteendeanpassningarna tycks avse att fungera som riskminimeringsstrategier för att undvika att bli utsatt för oönskade handlingar med antisemitiska förtecken. Ur det kvalitativa materialet kunde vi utläsa att våra respondenter skyler sin judiska identitet för att undvika stigmatisering. I praktiken inskränker dessa konsekvenser av otryggheten de judiska respondenternas religions- och yttrandefrihet och utgör ett hot mot den svenska konstitutionen och FN:s deklaration om mänskliga rättigheter

Rhizome Fragmentation by Vertical Disks Reduces Elymus repens Growth and Benefits Italian Ryegrass-White Clover Crops

Tillage controls perennial weeds, such as Elymus repens, partly because it fragments their underground storage organs. However, tillage is difficult to combine with a growing crop, which limits its application. The aim of this study was to evaluate how soil vertical cutting with minimum soil disturbance and mowing affect the growth and competitive ability of E. repens in a grass–clover crop. A tractor-drawn prototype with vertical disks was used to fragment E. repens rhizomes with minimal soil and crop disturbance. In experiments performed in 2014 and 2015 at a field site close to Uppsala, Sweden, the rhizomes were fragmented before crop sowing (ERF), during crop growth (LRF), or both (ERF+LRF). Fragmentation was combined with repeated mowing (yes/no) and four companion crop treatments (none, Italian ryegrass, white clover, and grass/clover mixture). The results showed that in the grass–clover crop, rhizome fragmentation reduced E. repens rhizome biomass production and increased Italian ryegrass shoot biomass. ERF and LRF both reduced E. repens rhizome biomass by about 38% compared with the control, while ERF+LRF reduced it by 63%. Italian ryegrass shoot biomass was increased by 78% by ERF, 170% by LRF and 200% by ERF+LRF. Repeated mowing throughout the experiment reduced E. repens rhizome biomass by about 75%. Combining repeated mowing with rhizome fragmentation did not significantly increase the control effect compared to mowing alone. We concluded that rhizome fragmentation using vertical disks can be used both before sowing and during crop growth to enhance the controlling effect of grass–clover crops on E. repens

Diversification improves the performance of cereals in European cropping systems

In the face of climate change, cropping systems need to achieve a high performance, providing food and feed and adapting to variable environmental conditions. Diversification of cropping systems can support ecosystem services and associated biodiversity, but there is little evidence on which temporal field arrangement affects the performance of crop yields (productivity and stability), partly due to a lack of long-term data and appropriate indicators. The objectives of this study were to quantify the effect of cropping system diversification on yield stability, environmental adaptability, and the probability of diversified systems to outperform less diverse cereal-based systems in Europe. Spring and winter cereal yields were analyzed from long-term field experiments from Sweden, Scotland, and France. We investigated diversification through (i) introduction of perennial leys, (ii) increasing the proportion of ley in the rotation, (iii) varying the order in which crops are positioned in the rotation, (iv) introduction of grain legumes, and (v) introduction of cover crops. The results showed that cereal crops within cropping systems incorporating perennial leys outperformed systems without leys in 60–94% of the comparisons with higher probabilities at low fertilizer intensities. The yield stability of oat did not differ, but mean yields were 33% higher, when grown directly after the ley compared to oat grown two years later in the crop sequence under similar management. Durum wheat grown in a cropping system with grain legumes had higher yields in lower-yielding environmental conditions compared to rotations without legumes. Diversification with cover crops did not significantly affect yield stability. We conclude that diverse cropping systems can increase cereal productivity and environmental adaptability and are more likely to outperform less diverse systems especially when introducing perennial forage legumes into arable systems. Effects of diversification on cereal yield stability were inconsistent indicating that higher productivity is achievable without reducing yield variability. These novel findings can support the design of more diverse and high-performing cropping systems

Diversification improves the performance of cereals in European cropping systems

International audienceAbstract In the face of climate change, cropping systems need to achieve a high performance, providing food and feed and adapting to variable environmental conditions. Diversification of cropping systems can support ecosystem services and associated biodiversity, but there is little evidence on which temporal field arrangement affects the performance of crop yields (productivity and stability), partly due to a lack of long-term data and appropriate indicators. The objectives of this study were to quantify the effect of cropping system diversification on yield stability, environmental adaptability, and the probability of diversified systems to outperform less diverse cereal-based systems in Europe. Spring and winter cereal yields were analyzed from long-term field experiments from Sweden, Scotland, and France. We investigated diversification through (i) introduction of perennial leys, (ii) increasing the proportion of ley in the rotation, (iii) varying the order in which crops are positioned in the rotation, (iv) introduction of grain legumes, and (v) introduction of cover crops. The results showed that cereal crops within cropping systems incorporating perennial leys outperformed systems without leys in 60–94% of the comparisons with higher probabilities at low fertilizer intensities. The yield stability of oat did not differ, but mean yields were 33% higher, when grown directly after the ley compared to oat grown two years later in the crop sequence under similar management. Durum wheat grown in a cropping system with grain legumes had higher yields in lower-yielding environmental conditions compared to rotations without legumes. Diversification with cover crops did not significantly affect yield stability. We conclude that diverse cropping systems can increase cereal productivity and environmental adaptability and are more likely to outperform less diverse systems especially when introducing perennial forage legumes into arable systems. Effects of diversification on cereal yield stability were inconsistent indicating that higher productivity is achievable without reducing yield variability. These novel findings can support the design of more diverse and high-performing cropping systems

Mellangrödor i växtföljden - för kolinlagring och effektivt kväveutnyttjande

Rapporten beskriver mellangrödors funktion för kolinlagring i jordbruksmark i relation till andra funktioner och miljörisker. Den består av en kunskapsgenomgång, en inventering av data från fältförsök samt en sammanfattning av odlares erfarenheter vid en workshop. Vår definition av mellangröda är: En gröda som har sin huvudsakliga tillväxt mellan två huvudgrödor, och där syftet med att odla mellangrödan kan variera.Mellangrödan ger kolinlagring, särskilt rötternaKolinlagringen av en mellangröda har uppskattats till ca 320 kg kol i medeltal per ha och år, men variationen är stor. Vi sammanställde resultat från fältförsök med mellangrödor under 30 år. För insådda gräsfånggrödor skiljer sig biomassaproduktionen i medeltal inte så mycket åt mellan olika regioner, medan variationen är större för eftersådda mellangrödor. Det saknas kunskap för att kunna ge konkreta råd om hur artval och jordbearbetningsstrategier m.m. för mellangröda kan användas för att optimera stabiliseringsprocesserna för kol i marken. Mellangrödans rötter bidrar med ca 2,5 gånger större inlagring än den ovanjordiska grönmassan. Mätningar vi funnit visar en stor variation i viktförhållandet mellan skott och rot, som beror på arters variation, men också på osäkerheter i provtagning och metoder.Utmaningar för odlarnaBåde försök och odlares erfarenheter vittnar om utmaningar med sådd av mellangrödor efter skörd, särskilt på jordar med hög lerhalt. Det handlar om att hinna så direkt efter huvudgrödans skörd för att lyckas med etableringen och för att utnyttja hösten för tillväxt. Att ge sådd av mellangrödan lika hög prioritet som en huvudgröda var ett råd som erfarna odlare poängterade vid en workshop. Det finns olika tankesätt och strategier kring val av arter, beroende på syftet med mellangrödan. Genom artblandningar kan man också kombinera funktioner. Det finns inga tydliga råd för arter som särskilt främjar kolinlagring utan det viktigaste är stor tillväxt, hög kol-kväve-kvot (C/N-kvot), stor rotbiomassa samt baljväxtinslag. Hushållning med kvävet En nordisk sammanställning visade att mellangrödor i medeltal minskade kväveläckaget med drygt 40 %. Tidpunkt för nedbrukning eller kemisk avdödning är metoder för att styra återmineraliseringen och kväveverkan i nästa gröda. För frostkänsliga mellangrödor med låg C/N-kvot finns en risk att kvävet frigörs så snabbt att det hinner utlakas innan våren. Under sådana förhållanden ökar också risken för lustgasemissioner. Mer kunskap behövs om hur kväveomsättning påverkas och hur lustgasemissioner kan minimeras, för att kunna anpassa mellangrödesystemen efter olika odlingskrav och klimatets förändring