The Texas Department of Transportation (TxDOT) uses the Pavement Management Information Systems (PMIS) to store and analyze pavement data, and to summarize information needed to support pavement-related decisions. The information on overall condition of the pavement is stored in PMIS, measured with various scores based on visual distress and ride quality surveys. However, a direct measure of the pavement structural condition is currently not in use. A network-level index that can distinguish pavements that require Preventive Maintenance (PM) from those that require Rehabilitation (Rhb) is required, because, it is not cost-effective to apply PM treatments to pavements that are structurally inadequate. The necessity to use an index to improve pavement treatment selection process, especially under financial constraints has motivated this research. The objective of this research is to validate the pavement Structural Condition Index (SCI) developed under a previous Research Project 0-4322, and to develop guidelines for implementing the SCI at the network level. / text

In countries with severe winters such like Canada, winter road maintenance (WRM) operations, such as plowing, salting and sanding, play an indispensible role in maintaining good road surface conditions and keeping roads safe. WRM is, however, also costly, both monetarily and environmentally. The substantial direct and indirect costs associated with WRM have stimulated significant interest in quantifying the safety and mobility benefits of winter road maintenance, such that systematic cost-benefit assessment can be performed. A number of studies have been initiated in the past decade to identify the links between winter road safety and factors related to weather, road, and maintenance operations. However, most of these studies have focused on the effects of adverse weather on road safety. Limited efforts have been devoted to the problem of quantifying the safety benefits of winter road maintenance under specific road weather conditions. Moreover, the joint effects of and complex interactions between road driving conditions, traffic and maintenance and their impact on traffic safety have rarely been studied. This research aims to determine the effect of WRM on road safety during snow storm events and develop models that can be used to quantify the safety benefit of alternative winter road maintenance policies, strategies and practices. Two integral aspects of collision risk were investigated, namely, collision frequency and severity. Collision frequency models were developed using winter storm collision data compiled for six winter seasons (2000 to 2006) for a total of 31 highway routes across Ontario. A comprehensive measure, namely, road surface condition index (RSI), was proposed to represent the road surface conditions during a variety of snow events. RSI was used as a surrogate measure to capture the effects of WRM. Other factors related to weather, traffic and road features were also accounted for in the analysis. Problems associated with data aggregation were also investigated. For this purpose, two different datasets were formed, namely, event-based data (EBD) which aggregates data by snow storm events and hourly based data (HBD) which includes hourly records of collision counts and other related factors. These two data sets of different aggregation levels were then used to investigate the effects of data aggregation and correlation (within – event) as well as to develop models for different purposes of benefit analyses. For EBD, Negative Binomial models and Generalized Negative Binomial models were calibrated whereas for HBD, Generalized Negative Binomial models and multilevel Poisson Lognormal models were calibrated. Generalized Negative Binomial models were found to best fit the data for both datasets. It was found that addition of site specific variables improves model fit. RSI and exposure were found significant for all the models and datasets. Weather factors such as visibility, wind speed, precipitation, and air temperature were also found to have statistically significant effects on collision frequency. All the models were consistent in terms of effects of different variables. The EBD models are useful to quantify the effect of different maintenance service standards and policies with limited information on the details of the weather events and traffic. On the other hand, HBD models have a higher level of reliability capable of providing more accurate estimates on road accidents. As a result, they are useful for determining the effects of different treatment operations. Several examples were employed to demonstrate the application of the developed models, such as quantifying the benefits of alternative maintenance operations and evaluating the effects of different service standards using safety as a performance measure. To enable a comprehensive risk analysis, collisions under both all-weather conditions and snow storm conditions over the six winter seasons were analyzed to identify the relationship between collision severity and various factors related to road weather and surface conditions, road characteristics, traffic, and vehicles etc., on collision severity. A multilevel modeling framework was introduced to capture the inherent hierarchy between collisions, vehicles and persons involved within the collision data. For each collision data set, three alternative severity models, namely, multinomial models, ordered logit models and binary logit models, were calibrated and compared. It was found that multilevel multinomial logit models were best fit to the data. Moreover issues related to different levels of aggregation were also discussed and results from occupant based data were found to be more reasonable and in line with general literature. Different individual, vehicle, environment and accident location factors were found to have a statistically significant effect on the injury severity levels. Contributing factors at the individual and vehicle levels include driver condition, driver sex, driver age, position in vehicle, use of safety device such as seat belt, vehicle type, vehicle age and vehicle condition. Roadway and environment factors include number of lanes, speed limit, road alignment, RSI/road surface condition, wind speed, and visibility. Other factors include light, and traffic volume. Two case studies were conducted to demonstrate the application of the developed models in conjunction with the accident frequency models for cost benefit analysis. This research was the first to investigate the direct link between road surface conditions and collisions at an operational level. It has been shown that the developed models are capable of evaluating alternative winter road maintenance policies and operations and assessing the safety benefit of a particular winter road maintenance strategy or decision. This research is also the first to conduct an in-depth analysis on the problem of winter road safety at a disaggregate level that captures detailed temporal variation (e.g., hourly and by storm event)) within small spatial aggregation units (road sections corresponding to actual patrol routes). The safety models developed from this research could be easily incorporated into a decision support tool for conducting what-if analysis of alternative winter road maintenance policies and methods. Moreover these models could provide a mechanism to estimate road safety level based on road surface as well as weather and traffic conditions and therefore could potentially be used for generating safety related information for travelers as part of a winter traffic management scheme. Directions for future work are also provided at the end of this document.

The Swedish road network is maintained by the Swedish Transport Administration, municipalities, and entrepreneurs with the goal of keeping the roads in satisfactory condition for traffic. The road operators are responsible for different roads and have several legislations that regulate construction and operation. One important aspect of winter road maintenance is the monitoring of the road situation ahead in order to call out resources for preventive measures. This study is performed at the company NIRA Dynamics with the purpose of going towards more digitized winter road information. The study explores different winter maintenance organizations in Sweden, investigates the importance of the information needed to be able to detect when roads are deemed too risky, and tries to gain an understanding of how the vehicle data provided by NIRA Dynamics best can provide a service for the winter road maintainers. This study is based on eight semi-structured interviews, user-tests aswell as a literature study. The findings of the study show that different winter maintenance organizations can differ a lot depending on the size and governing policies of the municipalities or entrepreneurs. The main differences can be found in their requirements and their method of monitoring the road situation ahead. The findings also show that the vehicle data is promising and has the potential to optimize and improve the overall winter maintenance planning. However, implementing and understanding the vehicle data in a real-world context requires collaboration from the different organizations to fulfill its value.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / A pavement management system (PMS) is a tool that supports decision-making specialists to maintain the pavement at an optimal service level. The absence of a PMS could lead to inadequate decision-making, a disorganized road inventory, poor selection in road maintenance techniques and inefficient technical support to justify the execution of maintenance activities. For these reasons, this research proposes the application of a PMS, with the objective of improving and standardizing the processes for evaluating the condition of roads that are under the jurisdiction of low-budget government organizations, guaranteeing the selection of the most appropriate type of maintenance. As a case of study, a 1.1 km local road located in one of the districts of Lima was evaluated, which was divided into 11 sections. With this evaluation, it was obtained that 2,605.43 m2 of the total road is in poor condition, due to the presence of functional failures. For the identification of failures, the pavement condition index (PCI), the international roughness index (IRI) and the present serviceability index (PSI) were used to determine the condition, roughness and serviceability of the pavement. In conclusion, it was identified that the proposed PMS is adequately adapted to the way of working and available budget of a local administration, since if it is applied it would only spend 20.55% of the fund that would be destined to a total reconstruction of road.

This thesis is a documentation of research on Geographical Information Technologies (GITs) as decision support tools in Road Infrastructure Maintenance (RIM) in Uganda. The main objective is to develop an operational framework within which the use of geo-information technologies can be enhanced as decision support tools in road infrastructure maintenance works of Uganda. Specifically, the research identifies the gaps and limitations in the use of and access to GITs for RIM and defines an algorithmic framework to accentuate the use of GITs in RIM. The research undertook a participatory multifaceted approach that included a review of documentation both in academia, in form of articles, journals, books, reports and research theses and also reports and documents prepared by the road infrastructure maintenance sector. Participant observations, field visits and measures, interviews and workshops were also triangularly employed to obtain the inherent answers. Content and GIS analyses were made to arrive at the findings that are documented in the papers which are part of the thesis. The gaps to using GITs in RIM have been found to include the lack of standardized datasets to address key nation-wide and local maintenance requirements, challenges on coordinating how geospatial data are acquired and utilized and the collection of duplicate data sets at the local and national levels. Also, the present institutional arrangements do not permit the formation of lasting partnerships and operating under a coordinated GIS infrastructure. The limitations to access of GITs in the sector include; the absence of policies for accessibility and standard use of GITs, lack of infrastructure to support utilization of geographic datasets, unavailability of and limited accessibility to geographic data, lack of geospatial capacity at individual and organizational levels and the digital divide. A nondeterministic algorithmic framework approach to the accentuation of GIT usage in RIM has been suggested. This framework involves strategies on; developing a policy on data collection guidelines emphasizing the use of GPS, satellite imagery and GIS, continuous undertaking of capacity building in the benefits of GIT use and the science involved, establishment of Local Spatial Data Infrastructures (LSDI) for road maintenance data and setting aside yearly budgets for the defined activities. In this framework, the dynamic segmentation data model is considered a superior data storage strategy for road maintenance data within the GIS. Dynamic Segmentation is the process of transforming linearly referenced data (also known as events) that have been stored in a table into features that can be displayed, queried and analyzed on the map through computations. It allows for the location of multiple events stored with linearly referenced attributes without any duplication with route geometry and in effect supports sharing of network infrastructure with different applications

<p>The Swedish Road Administration (SRA) is responsible for maintenance of the state-run roads in Sweden. The SRA also has an overarching responsibility for the state of the environment in the road transport sector. The overall aim of this thesis is to examine the implementation of environmental requirements in SRA road maintenance contracts and to develop an improved model for the implementation of environmental requirements, making it easier for the SRA to establish an optimal contracting strategy for routine road maintenance. Using several qualitative methodologies, the thesis is mainly based on a content analysis of 18 tender documents, two case studies consisting of five cases and a questionnaire. The study shows that the SRA have stipulated environmental requirements in procurements of routine road maintenance since 1997. The formulation of the environmental requirements was initially carried out at the Regional Road Management Directorates. However, in the case of trucks and construction vehicles relevant organisations were given the opportunity to actively participate in the development of environmental requirements. The contractors in the study fulfil about three-quarters of the environmental requirements in the contracts. The main reasons for not complying with the environmental requirements are: i) absence of consultation with municipalities and competent authorities, and ii) inadequate communication of environmental requirements to subcontractors. The benefit to the environment of laying down environmental requirements for road maintenance is difficult to assess, due to unclear environmental requirements and the fact that the SRA does not systematically follow up the environmental requirements. The findings of the research indicate that the SRA have made a serious effort to integrate environmental aspects in their maintenance contracts through the use of environmental requirements. However, the SRA need to adopt a more systematic approach towards road maintenance contracts in order to make green procurement an effective tool for environmental adaptation of road maintenance. The thesis proposes an improved process for development, implementation and follow-up of environmental requirements. The proposed process can be summarised in five criteria that need to be fulfilled in order to achieve an environmentally efficient application of environmental requirements: i) the environmental requirements have to be based on legislation, environmental quality objectives, identified environmental problems and/or research, ii) environmental indicators and baselines have to be established in order to facilitate follow-up of compliance with the requirements, iii) the environmental requirements have to be stated clearly in order to limit misinterpretations and to facilitate follow-up, iv) the contractors have to develop working processes, routines and training based on the environmental requirements, v) routines for following-up compliance with the requirements and the environmental effectiveness need to be developed, and there has to be a feedback of the results. Furthermore, the purchasing function needs to be integrated with the implementation of the contracts. Although, having faced several problems during the introduction of environmental requirements, the SRA have managed to meet the main arguments that are used for justification of green procurement. However, if slightly changed, the process of green procurement has the potential of becoming an important tool in the work for enhancing the environmental performance of the SRA.</p>

O patrimônio de infraestrutura rodoviária brasileira através dos tempos está sobrevivendo com investimentos com grandeza de valor bem abaixo do que muitos outros países estão alocando. A questão de quanto investir em infraestrutura de transportes depende de múltiplas variáveis como a situação política e econômica do país, a característica da frota, sua dimensão territorial, sua matriz, os tipos de pavimentos utilizados e as condições climáticas. Portanto, estimar um valor a ser empregado em manutenção rodoviária de forma recomendável, deve ser resultado dos estudos que envolvam essas variáveis, como elas interagem entre si e como esse investimento retorna para a sociedade. Diante de tantas áreas precárias, administrar recursos para a infraestrutura de transportes é um desafio a ser ainda vencido no Brasil. É engajada nesse desafio, que essa dissertação é composta por três artigos que abordam os principais assuntos: (i) avaliação da gestão da manutenção rodoviária no Brasil, quanto a sua abrangência, investimentos e as experiências internacionais; (ii) os conceitos e etapas de um SGP (Sistema de Gerência de Pavimentos) e a sua importância no planejamento das intervenções de manutenção; (iii) aplicação prática com o software Highway Development and Management (HDM-4), avaliando os resultados econômicos com as variáveis International Roughness Index (IRI) e Volume Médio Diário (VDM) do tráfego iniciais de segmentos de uma rodovia federal, utilizando como alternativas de projeto programas usuais adotados pelos gestores da rodovia. A terceirização dos serviços de manutenção pelos departamentos rodoviários exige que tenham que planejar e administrar contratos de manutenção por pouco ou longo período. A aplicação prática do HDM-4 demonstra que, o planejamento, um componente de um SGP, deve ser considerado permanentemente pelos administradores públicos ou privados. A questão de quanto investir em manutenção nesse contexto depende de como se investiu em momento antecedente, tanto com os serviços de infraestrutura como nas etapas de inventário da malha, planejamento e elaboração de projetos. O sistema HDM-4 necessita de dados de entrada, tais como: características geométricas, mecânicas, dados históricos e de tráfego dos segmentos rodoviários; que devem ser preservados pelos gestores do sistema, de maneira que permita prever o desempenho do pavimento, os custos e benefícios para um período planejado. Durante a análise dos resultados de Valor Presente Líquido (VPL) com os IRI e VDM iniciais, verificouse que as maiores diferenças se encontravam nos segmentos com mesmo intervalo de IRI inicial mas com tráfego superior. As características da frota, seus custos operacionais bem como seus coeficientes de calibração devem ser considerados nas análises com o software HDM-4, visando uma boa gestão na manutenção rodoviária. Tendo em vista o fato do tráfego influenciar nos resultados e podendo alterar o planejamento da manutenção, se percebe como é importante o controle do gestor da rodovia nas cargas efetivas que estão sendo transportadas. / The patrimony of Brazilian highway infrastructure through the ages is surviving with investments of magnitude value well below of what many other countries are allocating. The question of how much to invest in transport infrastructure depends on multiple variables such as the political and economic situation of the country, the characteristic of the fleet, its territorial dimension, its matrix, the types of used pavements and weather conditions. Therefore, to estimate a value to be used in road maintenance of a recommended way should be the result of the studies involving these variables, how they interact and how this investment returns to society. In face of so many precarious areas, managing resources for transport infrastructure is a challenge yet to be overcome in Brazil. It is engaged in this challenge, that this thesis consists of three articles that discuss the main issues: (i) assess the management of road maintenance in Brazil, as its scope, investment and international experiences; (ii) the concepts and steps of a Pavement Management System (PMS) and its importance in the planning of maintenance operations; (iii) practical application with the software Highway Development and Management (HDM-4), evaluating the economic results with the variables International Roughness Index (IRI) and Annual Average Daily Traffic (AADT) of the initial traffic segments of a federal motorway, using as alternative project usual programs adopted by the highway managers. The outsourcing of the maintenance services by road departments requires that they have to plan and manage maintenance contracts for little or long period. The practical application of the HDM-4 shows that the planning, a component of the PMS should be considered permanently by public or private administrators. The question of how much to invest in maintenance in this context depends on how you invested in previous time, both with infrastructure services as with the inventory stages of the motorway network, planning and preparation of projects. The HDM-4 system requires input data, such as geometric and mechanical characteristics, historical data and traffic of road segments that should be preserved by system managers, in order to foresee the pavement performance, costs and benefits to a planned period. During the analysis of the results of Net Present Value (NPV) with the initial IRI and AADT, it was found that the greatest differences were in the same initial IRI segments range but with higher traffic. The fleet characteristics, their operating costs and their calibration coefficients should be considered in the analysis with the HDM-4 software, aiming at a good management in road maintenance. In view of the fact that traffic influences the results and can change the maintenance planning, one can perceive that the road manager control on actual loads being transported is important.

The Swedish Road Administration (SRA) is responsible for maintenance of the state-run roads in Sweden. The SRA also has an overarching responsibility for the state of the environment in the road transport sector. The overall aim of this thesis is to examine the implementation of environmental requirements in SRA road maintenance contracts and to develop an improved model for the implementation of environmental requirements, making it easier for the SRA to establish an optimal contracting strategy for routine road maintenance. Using several qualitative methodologies, the thesis is mainly based on a content analysis of 18 tender documents, two case studies consisting of five cases and a questionnaire. The study shows that the SRA have stipulated environmental requirements in procurements of routine road maintenance since 1997. The formulation of the environmental requirements was initially carried out at the Regional Road Management Directorates. However, in the case of trucks and construction vehicles relevant organisations were given the opportunity to actively participate in the development of environmental requirements. The contractors in the study fulfil about three-quarters of the environmental requirements in the contracts. The main reasons for not complying with the environmental requirements are: i) absence of consultation with municipalities and competent authorities, and ii) inadequate communication of environmental requirements to subcontractors. The benefit to the environment of laying down environmental requirements for road maintenance is difficult to assess, due to unclear environmental requirements and the fact that the SRA does not systematically follow up the environmental requirements. The findings of the research indicate that the SRA have made a serious effort to integrate environmental aspects in their maintenance contracts through the use of environmental requirements. However, the SRA need to adopt a more systematic approach towards road maintenance contracts in order to make green procurement an effective tool for environmental adaptation of road maintenance. The thesis proposes an improved process for development, implementation and follow-up of environmental requirements. The proposed process can be summarised in five criteria that need to be fulfilled in order to achieve an environmentally efficient application of environmental requirements: i) the environmental requirements have to be based on legislation, environmental quality objectives, identified environmental problems and/or research, ii) environmental indicators and baselines have to be established in order to facilitate follow-up of compliance with the requirements, iii) the environmental requirements have to be stated clearly in order to limit misinterpretations and to facilitate follow-up, iv) the contractors have to develop working processes, routines and training based on the environmental requirements, v) routines for following-up compliance with the requirements and the environmental effectiveness need to be developed, and there has to be a feedback of the results. Furthermore, the purchasing function needs to be integrated with the implementation of the contracts. Although, having faced several problems during the introduction of environmental requirements, the SRA have managed to meet the main arguments that are used for justification of green procurement. However, if slightly changed, the process of green procurement has the potential of becoming an important tool in the work for enhancing the environmental performance of the SRA. / QC 20101012

I avhandlingen studeras hur kostnadseffektiva underhålls- (uh-)planer för belagd väg kan genereras, på basis av information om aktuellt vägytetillstånd och funktionella modeller för kostnads- och tillståndsförändringar, delvis utvecklade i samarbete med svenska Vägverket (VV). Tilltänkt användning är på strategisk och programnivå, innan mer detaljerad objektinformation finns att tillgå. Till skillnad från hittills använda modeller, så genereras individuella uh-planer för varje vägsegment (en homogen vägsträcka vad gäller aktuellt beläggningstillstånd och beläggningshistorik), i kontinuerliga tillstånds- och åtgärdsrum. Genom användning av Lagrangerelaxerande optimeringsteknik, så kan de speciella nytto/kostnads-kvot-villkor som VV ålägger varje uh-objekt naturligen hanteras med dualpriser för budgetvillkoren. Antalet vägsegment som konkurrerar om budgetmedlen är vanligtvis stort. Data från VV:s Vägdatabank för Värmland har använts, omfattande ca 9000 vägsegment. Genom den stora datamängden har datorprogrammen implementerats för parallellbearbetning. Under avhandlingsarbetet har projektet beviljats tillgång till Monolith PCklustret vid NSC. För att kunna reducera optimeringskörtiderna har modell- och metodutveckling varit nödvändig. Genom att aggregera vägsegmenten till vägklasser har goda startvärden på dualpriserna erhållits. Genom utvecklingen av en speciell restvärdesrutin har den explicit behandlade tidsperioden kunnat reduceras. Vid lösandet av det duala subproblemet har speciell uppmärksamhet ägnats åt de diskretiseringseffekter som uppstår i metoden dynamisk programmering. En typ av tillämpning avser ett delvägnät, exempelvis en väg. Valideringsstudier har genomförts på väg 63 i Värmland – med lovande men inte tillfredsställande resultat (se nedan). En speciell modell för samordnat uh beaktar stordriftsfördelarna vid samtidig åtgärd på en hel vägsträcka. Den andra huvudtypen av studier gäller ett helt nätverk. Flera metodtyper har tillämpats, både för att lösa de relaxerade optimeringsproblemen och för att generera uhplaner som uppfyller budgetvillkoren. För en anständig diskretisering är körtiderna för hela Värmland mindre än 80 CPU-timmar. Genom en a posteriori primal heuristik reduceras kraven på parallellbearbetning till ett litet PC-kluster. Avhandlingen studerar vidare effekterna av omfördelade budgetmedel samt en övergång till en transparent, stokastisk modell – vilka båda visar små avvikelser från basmodellen. Optimeringsresultaten för Värmland indikerar att budgetnivåer på ca 40% av Värmlands verkliga uh-budget är tillräckliga. Dock saknas viktiga kostnadsdrivande faktorer i denna första modellomgång, exempelvis vissa funktionella prestanda (säkerhet), all miljöpåverkande prestanda (buller etc.) och strukturell prestanda (ex.vis bärighet, som enbart modelleras via ett åldersmått). För ökad tilltro till PMS i allmänhet och optimering i synnerhet, bör avvikelserna analyseras ytterligare och leda till förbättringar vad gäller tillståndsmätning, tillståndseffekt- &amp; kostnadsmodellering samt matematisk modellering &amp; implementering. / The thesis deals with the generation of cost efficient maintenance plans for paved roads, based on database information about the current surface conditions and functional models for costs and state changes, partly developed in cooperation with Vägverket (VV, Swedish Road Administration). The intended use is in a stage of budgeting and planning, before concrete project information is available. Unlike the up to now used models, individual maintenance plans can be formulated for each segment (a homogeneous road section as to the current pavement state and paving history), in continuous state and works spaces. By using Lagrangean relaxation optimisation techniques, the special benefit/cost-ratio constraints that VV puts on each maintenance project can be naturally mastered by dual prices for the budget constraints. The number of segments competing for budget resources is usually large. Data from VV Vägdatabank (SRA Road Database) in county Värmland were used, comprising around 9000 road segments. Due to the large data amount the implemented programs rely on parallel computation. During the thesis work, access to the PC-cluster Monolith at NSC was granted. In order to reduce optimisation run times, model &amp; method development was needed. By aggregating the road segments into road classes, good initial values of the dual prices were achieved. By adding new state dimensions, the use of the Markov property could be motivated. By developing a special residual value routine, the explicitly considered time period could be reduced. At solving the dual subproblem special attention was paid to the discretization effects in the dynamic programming approach. One type of study is on a sub-network, e.g. a road. Validation studies were performed on road 63 in Värmland – with promising but not satisfactory results (see below). A special model for co-ordinated maintenance considers the fine-tuned cost effects of simultaneous maintenance of contiguous road segments. The other main type of study is for a whole network. Several method types have been applied, both for solving the relaxed optimisation problems and for generating maintenance plans that fit to the budgets. For a decent discretization, the run time for the whole Värmland network is less than 80 CPU-hrs.A posterior primal heuristics reduces the demands for parallel processing to a small PC-cluster.The thesis further studies the effects of redistributing budget means, as well as turning to a transparent stochastic model – both showing modest deviations from the basic model. Optimisation results for Värmland indicate budget levels around 40% of the actual Värmland budget as sufficient. However, important cost triggers are missing in this first model round, e.g., certain functional performance (safety), all environmental performance (noise etc.) and structural performance (e.g. bearing capacity, only modelled by an age measure). For increased credibility of PMS in general and optimisation in particular, the discrepancies should be further analysed and lead to improvements as to condition monitoring, state effect &amp; cost modelling and mathematical modelling &amp; implementation.

Baigiamajame magistro darbe yra nagrinėjamos Lietuvoje žiemos metu naudojamos intelektinės transporto sistemos. Didžiausias dėmesys yra skiriamas KOSIS trūkumo – nesugebėjimo prognozuoti – pašalinimui. Darbo tikslas yra išsiaiškinti, ar yra galimybė, pasinaudojus minėtos sistemos teikiamais duomenimis, prognozuoti kritulių pradžios laiką VĮ „Vilniaus regiono keliai" prižiūrimuose keliuose. Darbo aktualumui atskleisti yra aptarta kritulių prognozės svarba tiek eismo dalyviams tiek kelių priežiūros įmonėms ypač šaltuoju metų laiku. Tikslui pasiekti yra aprašoma tyrimo metodiką, kurios pagrindą sudaro vėjo, nešančio kritulių debesis, greitis. Greičiui apskaičiuoti yra pateikiami teoriniai pagrindai, padedantys pasirinkti atitinkamus parametrus šio dydžio nustatymui. Žinant debesų judėjimo greitį yra parengtos prognozės, kurių rezultatai gretinami su realiai užfiksuotais laiko intervalais. Atlikus tyrimą yra nustatyta, kokiu spinduliu yra tikslinga atlikti tokias prognozes ir kokiam laikotarpiui galima prognozuoti. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, Lietuvoje naudojamos intelektinės transporto sistemos kelių priežiūroje žiemą, klimatinių sąlygų prognozavimo tyrimas, išvados ir pasiūlymai, literatūros sąrašas. Darbo apimtis – 71 p. teksto be priedų, 35 iliustracijos, 13 lentelės, 29 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai. / In this master thesis there are analysed intelligent transport systems used for winter road maintenance in Lithuania. The main attention is payed to Road Weather Information system. The aim of this thesis is to find out the posibility of forecasting the precipitation start time in Vilnius region using Road Weather stations information. All stations are located within a 200 km radius to the southwest of Vilnius region. At first there is a disputed importance of precipitation forecasting to drivers and road maintenance personnel especially during the winter season. In order to achieve the aim of this thesis, there are described forecasting method based on the wind speed. Also there is a theory that explains how to select basic parameters to calculate the wind speed. There are some forecasts made in this paperwork and their results are compared with real data. It helps to find out which stations are useful for further forecasting and what is the longest time of forecasting. The thesis includes 6 parts: introduction, survey of literature, Road Weather Information systems used for winter road maintenance in Lithuania, the reserach of weather forecasting, conclusions and suggestions, references. Pages - 71 p . text, 35 figures . , 13 tables . , 39 bibliographic sources . All appendixes are separately attached.