Factors influencing privatization of urban solid waste collection: some evidence from Spain

In this paper we analyse some of the organisational aspects of the urban solid waste collection and, in particular, the privatization modality of contracting out. We start by discussing some of the theoretical aspects of contracting out. We then specify and estimate an explanatory model on a sample of municipalities that we surveyed. Our purpose is twofold: on the one hand, we identify the economic factors at work when deciding to contract out the service and, on the other hand, we analyse the role of ideological factors in choosing between the public production of the service or contracting it out. The results show a significant effect of the demand for waste collection on contracting out. There also appears to be a neighbouring effect as the municipalities close to other cities that contract out are also more prone to do so. Finally, the decisions to contract seem to have been motivated by pragmatic rather than ideological reasons.

Classification of urban multi-angular image sequences by aligning their manifolds

When dealing with multi-angular image sequences, problems of reflectance changes due either to illumination and acquisition geometry, or to interactions with the atmosphere, naturally arise. These phenomena interplay with the scene and lead to a modification of the measured radiance: for example, according to the angle of acquisition, tall objects may be seen from top or from the side and different light scatterings may affect the surfaces. This results in shifts in the acquired radiance, that make the problem of multi-angular classification harder and might lead to catastrophic results, since surfaces with the same reflectance return significantly different signals. In this paper, rather than performing atmospheric or bi-directional reflection distribution function (BRDF) correction, a non-linear manifold learning approach is used to align data structures. This method maximizes the similarity between the different acquisitions by deforming their manifold, thus enhancing the transferability of classification models among the images of the sequence.

Educational expansion, intergenerational mobility and over-education

[eng] There is a vast literature on intergenerational mobility in sociology and economics. Similar interest has emerged for the phenomenon of over-education in both disciplines. There are no studies, however, linking these two research lines. We study the relationship between social mobility and over-education in a context of educational expansion. Our framework allows for the evaluation of several policies, including those affecting social segregation, early intervention programs and the power of unions. Results show the evolution of social mobility, over-education, income inequality and equality of opportunity under each scenario.

Inter-firm labor mobility and knowledge diffusion: a theoretical approach

[cat] Analitzem una economia amb dues característiques principals: la mobilitat dels treballadors implica transferència de coneixement i la productivitat de l’empresa augmenta amb l’intercanvi de coneixement. Cada empresa desenvolupa un tipus de coneixement que serà trasmès a la resta de la indústria mitjançant la mobilitat de treballadors. Estudiem dues estructures de mercat laboral i utilitzant un anàlisi comparatiu derivem les implicacions del model. Els resultats revelen com la mobilitat de treballadors depèn en la varietat i nivell del coneixement, la presència de costos de mobilitat, les institucions, la capacitat d’absorvir coneixement per part de les empreses i la mida de la indústria. Els resultats no depenen de l’estructura del mercat laboral.

On the industry experience premium and labor mobility

[cat] Hi ha evidència que l'experiència es remunera diferentment segons la indústria. Proposem un model teòric que explica aquestes diferències. Suposem que la mobilitat de treballadors aporta coneixement extern a l'empresa i això augmenta la seva productivitat. Els resultats mostren que l'experiència és millor remunerada en les indústries amb costos de mobilitat baixos, amb molt aprenentatge (learning-by-doing) i alt nivell tecnològic. A més, trobem una relació en forma de U entre la remuneració de l'experiència i el nivell d'absorció de coneixement extern, la substitutibilitat entre diferents tipus de treballadors i la varietat de coneixement dins la indústria. Els resultats són consistents amb l'evidència que les indústries intensives en I and D remuneren millor l'experiència.

A Review of Urban Geocoding,1973.

The purpose of this report is to describe and evaluate recent efforts in spatial referencing problems and to assess the utility of the developments for urban research, particularly. and to speculate on future developments in the field attempting to structure the issues and review literature and directions of what has become known as "geocoding."

Effects of urban development on the flood-flow characteristics of the Walnut Creek Basin, Des Moines Metropolitan area, Iowa,1978.

This report deals with the probable impact of urban development on the magnitude and frequency of flooding in the lower reach of the Walnut Creek Basin.

Evaluation of Temporary Ramp Metering for Work Zones, 2012

Ramp metering has been successfully implemented in many states to improve traffic operations on freeways. Studies have documented the positive mobility and safety benefits of ramp metering. However, there have been no studies on the use of ramp metering for work zones. This report documents the results from the first deployment of temporary ramp meters in work zones in the United States. Temporary ramp meters were deployed at seven urban short-term work zones in Missouri. Safety measures such as driver compliance, merging behavior, and speed differentials were extracted from video-based field data. Mobility analysis was conducted using a calibrated simulation model and the total delays were obtained for under capacity, at capacity, and over capacity conditions. This evaluation suggests that temporary ramp meters should only be deployed at work zone locations where there is potential for congestion and turned on only during above-capacity conditions. The compliance analysis showed that non-compliance could be a major safety issue in the deployment of temporary ramp meters for under-capacity conditions. The use of a three-section instead of a traditional two-section signal head used for permanent ramp metering produced significantly higher compliance rates. Ramp metering decreased ramp platoons by increasing the percentage of single-vehicle merges to over 70% from under 50%. The accepted-merge-headway results were not statistically significant even though a slight shift towards longer headways was found with the use of ramp meters. Mobility analysis revealed that ramp metering produced delay savings for both mainline and ramp vehicles for work zones operating above capacity. On average a 24% decrease in total delay (mainline plus ramp) at low truck percentage and a 19% decrease in delay at high truck percentage conditions resulted from ramp metering.

Evaluation of Variable Advisory Speed Limits in Work Zones, TPF-5(081), 2013

Variable advisory speed limit (VASL) systems could be effective at both urban and rural work zones, at both uncongested and congested sites. At uncongested urban work zones, the average speeds with VASL were lower than without VASL. But the standard deviation of speeds with VASL was higher. The increase in standard deviation may be due to the advisory nature of VASL. The speed limit compliance with VASL was about eight times greater than without VASL. At the congested sites, the VASL were effective in making drivers slow down gradually as they approached the work zone, reducing any sudden changes in speeds. Mobility-wise the use of VASL resulted in a decrease in average queue length, throughput, number of stops, and an increase in travel time. Several surrogate safety measures also demonstrated the benefits of VASL in congested work zones. VASL deployments in rural work zones resulted in reductions in mean speed, speed variance, and 85th percentile speeds downstream of the VASL sign. The study makes the following recommendations based on the case studies investigated: 1. The use of VASL is recommended for uncongested work zones to achieve better speed compliance and lower speeds. Greater enforcement of regulatory speed limits could help to decrease the standard deviation in speeds; 2. The use of VASL to complement the static speed limits in rural work zones is beneficial even if the VASL is only used to display the static speed limits. It leads to safer traffic conditions by encouraging traffic to slow down gradually and by reminding traffic of the reduced speed limit. A well-designed VASL algorithm, like the P5 algorithm developed in this study, can significantly improve the mobility and safety conditions in congested work zones. The use of simulation is recommended for optimizing the VASL algorithms before field deployment.

Integrated Risk Management for Improving Internal Traffic Control, Work-Zone Safety, and Mobility during Major Construction, TPF-5(081), 2012

Highway construction is among the most dangerous industries in the US. Internal traffic control design, along with how construction equipment and vehicles interact with the traveling public, have a significant effect on how safe a highway construction work zone can be. An integrated approach was taken to research work-zone safety issues and mobility, including input from many personnel, ranging from roadway designers to construction laborers and equipment operators. The research team analyzed crash data from Iowa work-zone incident reports and Occupational Safety and Health Administration data for the industry in conjunction with the results of personal interviews, a targeted work-zone ingress and egress survey, and a work-zone pilot project.