Dust suppressants were applied on fifteen 1 km long test sections at four sites in Sweden during three summer seasons with the objective to compare their relative efficiency and determine minimum application rates in Nordic climate. Dust generation from the test sections was measured both visually and by PM10 measurements. All products except lignosulphonate, sugar and bitumen emulsion showed acceptable efficiency. Chloride solutions were the most efficient. Results indicate the possibility to reduce application rates of chlorides by applying them as solutions instead of solids. The minimum application rate for a chloride solution was estimated at 0.8m(3)/km, which is equivalent to a rate reduction of 50% by weight compared with traditionally applied rates of solid chloride. The results are expected to reduce life cycle costs for gravel roads and contribute to environmental gains by reducing the release of dust into the atmosphere and chemicals into the environment.
A significant problem when dust-suppressing agents are used on gravel roads is that they tend to leach during rainfall. The purpose of this study is to illustrate this problem by using laboratory studies and studies in situ. Both capillary rise and leaching of suppressants were examined by using cylinders filled with wearing course material. Chloride was more prone than lignosulphonate to transport upwards by means of capillary rise, and therefore, it showed a more effective performance over a longer period of time. Optimal percentages of fine material for minimal lignosulphonate and chloride leaching were found to be 15% by weight and 10-15% by weight, respectively. Ions of calcium chloride seemed to flocculate clay particles, which probably prevents them from leaching. To study the in situ longevity of fine material in general, calcium carbonate, mesa, was used as a marker. The fine material in gravel wearing courses must be replenished regularly. Mesa loss was up to 80% after 1 year. DOI: 10.1061/(ASCE)MT.1943-5533.0000282. (C) 2011 American Society of Civil Engineers.
The objective of this study was to compile experiences regarding efforts by road authorities to satisfy the needs for efficient maintenance and the results of such efforts. The extent to which maintenance aspects are considered during road planning and design, as a potential for improvement of maintenance efficiency is studied. The study shows that such efforts have in many cases resulted in reduced maintenance costs. However, there are also indications that maintenance standards in some cases have declined, as the focus has been on reduction of the rate of recurring maintenance activities and prioritisation of some maintenance measures, e.g. winter maintenance, over other maintenance measures, e.g. pavement maintenance. The study also shows that efforts towards increased maintenance efficiency have one thing in common – namely that the main focus has been on improving operating practices and maintenance procedures. Road authorities have mostly ignored the improvement potentials that exist during the planning and design process through consideration of the interrelationship between geometrical road design and maintenance.
The cost of a road construction over its service life is a function of the design, quality of construction, maintenance strategies and maintenance operations. Unfortunately, designers often neglect a very important aspect which is the possibility to perform future maintenance activities. The focus is mainly on other aspects such as investment costs, traffic safety, aesthetic appearance, regional development and environmental effects. This licentiate thesis is a part of a Ph.D. project entitled “Road Design for lower maintenance costs” that aims to examine how the life-cycle costs can be optimized by selection of appropriate geometrical designs for the roads and their components. The result is expected to give a basis for a new method used in the road planning and design process using life-cycle cost analysis with particular emphasis on road maintenance. The project started with a review of literature with the intention to study conditions causing increased needs for road maintenance, the efforts made by the road authorities to satisfy those needs and the improvement potential by consideration of maintenance aspects during planning and design. An investigation was carried out to identify the problems which obstruct due consideration of maintenance aspects during the road planning and design process. This investigation focused mainly on the road planning and design process at the Swedish Road Administration. However, the road planning and design process in Denmark, Finland and Norway were also roughly evaluated to gain a broader knowledge about the research subject. The investigation was carried out in two phases: data collection and data analysis. Data was collected by semi-structured interviews with expert actors involved in planning, design and maintenance and by a review of design-related documents. Data analyses were carried out using a method called “Change Analysis”. This investigation revealed a complex combination of problems which result in inadequate consideration of maintenance aspects. Several urgent needs for changes to eliminate these problems were identified. Another study was carried out to develop a model for calculation of the repair costs for damages of different road barrier types and to analyse how factors such as road type, speed limits, barrier types, barrier placement, type of road section, alignment and seasonal effects affect the barrier damages and the associated repair costs. This study was carried out using a method called the “Case Study Research Method”. Data was collected from 1087 barrier repairs in two regional offices of the Swedish Road Administration, the Central Region and the Western Region. A table was established for both regions containing the repair cost per vehicle kilometre for different combinations of barrier types, road types and speed limits. This table can be used by the designers in the calculation of the life-cycle costs for different road barrier types.
The cost of a road construction over its service life is a function of design, quality of construction as well as maintenance strategies and operations. An optimal life-cycle cost for a road requires evaluations of the above mentioned components. Unfortunately, road designers often neglect a very important aspect, namely, the possibility to perform future maintenance activities. Focus is mainly directed towards other aspects such as investment costs, traffic safety, aesthetic appearance, regional development and environmental effects. This doctoral thesis presents the results of a research project aimed to increase consideration of road maintenance aspects in the planning and design process. The following subgoals were established: Identify the obstacles that prevent adequate consideration of future maintenance during the road planning and design process; and Examine optimisation of life-cycle costs as an approach towards increased efficiency during the road planning and design process. The research project started with a literature review aimed at evaluating the extent to which maintenance aspects are considered during road planning and design as an improvement potential for maintenance efficiency. Efforts made by road authorities to increase efficiency, especially maintenance efficiency, were evaluated. The results indicated that all the evaluated efforts had one thing in common, namely ignorance of the interrelationship between geometrical road design and maintenance as an effective tool to increase maintenance efficiency. Focus has mainly been on improving operating practises and maintenance procedures. This fact might also explain why some efforts to increase maintenance efficiency have been less successful. An investigation was conducted to identify the problems and difficulties, which obstruct due consideration of maintainability during the road planning and design process. A method called “Change Analysis” was used to analyse data collected during interviews with experts in road design and maintenance. The study indicated a complex combination of problems which result in inadequate consideration of maintenance aspects when planning and designing roads. The identified problems were classified into six categories: insufficient consulting, insufficient knowledge, regulations and specifications without consideration of maintenance aspects, insufficient planning and design activities, inadequate organisation and demands from other authorities. Several urgent needs for changes to eliminate these problems were identified. One of the problems identified in the above mentioned study as an obstacle for due consideration of maintenance aspects during road design was the absence of a model for calculating life-cycle costs for roads. Because of this lack of knowledge, the research project focused on implementing a new approach for calculating and analysing life-cycle costs for roads with emphasis on the relationship between road design and road maintainability. Road barriers were chosen as an example. The ambition is to develop this approach to cover other road components at a later stage. A study was conducted to quantify repair rates for barriers and associated repair costs as one of the major maintenance costs for road barriers. A method called “Case Study Research Method” was used to analyse the effect of several factors on barrier repairs costs, such as barrier type, road type, posted speed and seasonal effect. The analyses were based on documented data associated with 1625 repairs conducted in four different geographical regions in Sweden during 2006. A model for calculation of average repair costs per vehicle kilometres was created. Significant differences in the barrier repair costs were found between the studied barrier types. In another study, the injuries associated with road barrier collisions and the corresponding influencing factors were analysed. The analyses in this study were based on documented data from actual barrier collisions between 2005 and 2008 in Sweden. The result was used to calculate the cost for injuries associated with barrier collisions as a part of the socio-economic cost for road barriers. The results showed significant differences in the number of injuries associated with collisions with different barrier types. To calculate and analyse life-cycle costs for road barriers a new approach was developed based on a method called “Activity-based Life-cycle Costing”. By modelling uncertainties, the presented approach gives a possibility to identify and analyse factors crucial for optimising life-cycle costs. The study showed a great potential to increase road maintenance efficiency through road design. It also showed that road components with low investment costs might not be the best choice when including maintenance and socio-economic aspects. The difficulties and problems faced during the collection of data for calculating life-cycle costs for road barriers indicated a great need for improving current data collecting and archiving procedures. The research focused on Swedish road planning and design. However, the conclusions can be applied to other Nordic countries, where weather conditions and road design practices are similar. The general methodological approaches used in this research project may be applied also to other studies.
This paper presents a study that examines repair costs for different road barrier types and factors that influence these costs. The analyses focused on w-beam and cable barriers used as median barriers. To some extent, pipe barriers, Kohlswa-beam barriers, and concrete barriers were also studied. The influencing factors included in this study were road type, speed limit, barrier type, and seasonal effects. A case study was conducted in four regions of the Swedish Road Administration. Data were collected from 1,625 barrier repairs carried out during 2005 and 2006. The results show that the number of barrier repairs and the average repair cost per vehicle kilometer are higher along collision-free roads than along motorways and 4-lane roads. The results also show that the number of barrier repairs and the average repair cost per vehicle kilometer are higher for cable barrier than for other barrier types. No conclusion can be drawn regarding influence of speed limits on barrier repairs and associated costs as the result from the regions are divergent and not statistically significant. DOI: 10.1061/(ASCE)TE.1943-5436.0000227. (C) 2011 American Society of Civil Engineers.
This paper presents an investigation conducted to identify obstacles that prevent sufficient consideration of future road maintenance needs during the road planning and design phase. The investigation focuses on the road planning and design process within the Swedish Road Administration. For this reason the results are applicable for Nordic conditions concerning road design, maintenance, and climate. However, the results focus on general aspects of the planning and design process and ought to also be valid for other conditions outside the Nordic countries. The investigation was carried out using a method called ￜchange analysis,ￜ which consists of complementary steps for the analysis of problems, processes, and goals in order to identify necessary changes. The investigation identified several problems within the road planning and design process related to consulting, knowledge, planning and design activities, regulations, organization structure, and demands from other authorities. The
Denna arbetsrapport presenterar en studie som utfördes i syfte att undersöka hur vägbarriärer påverkar utförandet av plogningen och till detta relaterade kostnader. Målet var att kunna identifiera och beräkna de eventuella ökningar i snöplogningskostnaderna som tillkommer på grund av vägbarriärer. Studien utfördes med hjälp av en metod som heter ”Case Study Reasearch Strategy”. Fältstudier av snöplogningen utfördes på 6 vägsträckor. Fältstudierna täckte fyra vägtyper: motorväg, mötesfria vägar, 4-fältiga vägar och målade 2+1-vägar. De barriärtyper som studerades var betongbarriär, stållineräcke, rörräcke och w-profilräcke. Plogningskvalité, arbetsmiljö, trafiksäkerhet och framkomlighet studerades med hjälp av direkta observationer av plogningsaktiviteter på fält. Genom at mäta tiden för att ploga en viss sträcka bestämdes plogningshastigheten. Resultatet visade att vägbarriärtypen påverkar varken snöplogningshastigheten eller plogningstiden nämnvärt. Vidare visade resultatet att vägbarriärtypen inte påverkar snöplogningskvaliteten längs med mittremsan. Däremot, försämras plogningskvalitén längs vägrenar med betongbarriärar eller w-profilräcken som sidobarriärer. Det är dock svårt att beräkna de kostnader som tillkommer på grund av försämrad plogningskvalité. Trots att både trafiksäkerheten och framkomligheten försämrades drastiskt under plogningen, kunde man konstatera att dessa två aspekter inte påverkades av vägbarriärtypen.
För att kunna bygga en ny väg måste den först planeras och projekteras. Vägplanering innebär att man undersöker förutsättningarna för att bygga vägen t.ex. konsekvenser för miljö, samhälle, trafiksäkerhet, framkomlighet, tillgänglighet samt tekniska och ekonomiska förutsättningar. Vägprojektering innebär att man bestämmer vägens utformning på detaljnivå t.ex. vägsträckning, bredd, profil, vägutrustning, etc. Planering och projektering av vägar är en komplicerad process med tanke på alla komponenter som en väg består av samt alla aspekter som man måste ta hänsyn till under vägens livstid. Planerings- och projekteringsprocessen utgör en avvägning av många aspekter för att hitta den optimala lösningen. Drift- och underhållsåtgärder på vägnätet föranleds ofta av att problem uppstått på ett fåtal ställen. Kostnaden för att åtgärda dessa ställen kan uppgå till stora belopp under vägens livslängd. Med en lämpligare utformning av vägen hade dessa problem i en del fall sannolikt kunnat undvikas. Bland de aktörer, som är inblandade i planerings- och projekteringsprocessen, finns det olika åsikter om orsaken till att man inte tar tillräcklig hänsyn till drift- och underhållaspekten under planerings- och projekteringsskedet. Vissa aktörer tycker att det är projektörens kunskapsbrister som leder till att vägen får olämplig utformning avseende drift och underhåll. Andra tycker att det är en kombination av olika brister hos väghållaren. Dessa brister kan då finnas i såväl planerings- och projekteringsprocessen som i drift- och underhållsprocessen. Denna rapport presenterar resultatet för en förstudie som har utförts inom doktorandprojektet ”Vägprojektering för minskade drift- och underhållskostnader”. Syftet med förstudien var att identifiera brister och problem på övergripande nivå som leder till att man inte tar tillräcklig hänsyn till drift- och underhållsaspekten vid planerings- och projekteringsprocessen. Ett annat syfte med förstudien var att föreslå förändringsbehov inom planerings- och projekteringsprocessen genom att analysera de identifierade problemen, analysera verksamheten vid planering och projektering, analysera verksamhetens mål, formulera nya mål för verksamheten och fastställa de nödvändiga förändringsbehoven.
This study aimed at applying and evaluating a new approach for analyzing life-cycle costs for road components during the road planning and design process. Road median barriers were chosen as an example. The approach is based on a method called “Activity-Based Life-Cycle Costing using the Monte Carlo Simulation” for managing future costs and the associated risks. The results show a potential for increasing efficiency throughout the road planning and design process by minimizing the life-cycle costs of road components. The results also show that implementation of life-cycle cost analyses in the road planning and design process is possible, but difficult, mainly due to lack of relevant data.
This paper presents a study aimed at quantifying and comparing the risk of personal injuries associated with road barrier collisions. Documented data from actual barrier collisions, including post-impact collisions, in Sweden between 2005 and 2008 were analyzed. The analyses were based on the injury classification made by healthcare services. The injury rates, measured in number of injuries per vehicle kilometer travelled, were calculated for the different injury classes as a basis for evaluating barrier performance. The results show that the rate of injuries was higher due to collisions with flexible barrier systems, such as cable barrier, than with other semi-rigid and rigid barrier system, such as w-beam and concrete barriers. This result might be explained by a high rate of post-impact events, such as post-impact collisions, roll-overs and over-rides, associated with the placement and mechanical properties of the cable barriers. The study also showed a considerable difference in injury classifications made by the police and the healthcare services, as well as a considerable under-reporting of barrier collisions by the police.
Crack data can be collected using manual or automatic surveys. Traditionally, manual methods are used, and they are still the most common. Changing into automatic systems will enhance the efficiency of data collection as well as the objectivity. In this study the repeatability of an automatic crack data collection system using video images was evaluated. Ten repetitive measurements were made on a 10-km-long road section. Cracking was measured using six laser cameras attached to the same vehicle. The results from the two methods were compared. Simultaneously, a simplified manual windshield survey was conducted by three different persons, and the repeatability obtained was used for comparison with the repeatability established using the image and laser method, respectively. The correlation between repeated measurements using the two automatic systems was high, while the repeatability for the manual, subjective method was low. Suitable measures for crack characterization are discussed.
Application of the proper dust suppressant to a gravel road ensures road safety and riding comfort as well as creating a cleaner and healthier environment for residents in buildings adjacent to the road. It also reduces the need and cost for vehicle repair, road maintenance activities, and aggregate supplementation. Both field-based and laboratory research, using newly developed methods, were performed to evaluate the efficiency of various suppressants and the influence such factors as product concentration, leaching, and fine material content have on the efficiency of different products. A significant problem when using dust suppressants is their tendency to leach during rainfall due to their soluble properties. Residual chloride could be detected in the gravel wearing course over a longer period of time than lignosulphonate and, therefore, showed more effective long-term performance. Optimal percentages of fine material for minimal lignosulphonate and chloride leaching were found to be 15 percent by weight and 10-16 percent by weight, respectively. By applying a calcium- or magnesium chloride solution instead of traditionally used solids, the cost for annual dust control, as well as the environmental impact from the release of these chemicals in the environment, can be reduced by 50 percent. Ions of calcium chloride seemed to initiate flocculation of clay particles, thereby preventing them from leaching. Still, the fine material in gravel wearing courses has to be replenished regularly as indicated by studies of the longevity of fine material. Loss up to 80 percent was found after two years. Toxicity tests show that dust suppressant application for dust control purposes, at traditionally used application rates, does not constitute a threat to sensitive aquatic life. Tests on subsoil water samples indicated elevated chloride levels, which possibly could cause corrosion to pipes, but not high enough to flavour drinking water.
This review paper deals with the field of dust generation on gravel roads, dust suppressant performance and evaluation techniques. By applying the proper dust suppressant, matching the gravel road condition specific to the site, dust emission can be reduced, thereby providing a healthier ambient air environment, increasing road safety and ride comfort while reducing the need and cost of vehicle repair, road maintenance activities, and aggregate replacement. By applying the proper application rate of the dust suppressant, the cost of annual dust control as well as the environmental impact can be significantly reduced. Suitable measuring techniques for evaluating dust suppressant efficiency will facilitate the choice of the most appropriate dust suppressant and its optimal application rate.
Due to oxidation, breakdown, and leaching, dust suppressants will be lost from the gravel road surface. Methods for residual dust suppressant concentration supervision are a valuable tool for estimating life-length and optimal application rates, and, hence, efficiency of different products. The objective of this study was to identify methods for quantitative analyses of lignosulphonate and chloride, develop and adapt the methods for application on a gravel matrix, and validate the methods using samples collected in-situ. Results strongly suggest that the reliability and repeatability of the developed methods (23 % for lignosulphonate and 30 % for chloride, respectively) are acceptable for determination of relative variations in residual concentrations of dust suppressed gravel wearing courses.
Traffic-generated fugitive dust on gravel roads impairs visibility and deposits on the adjacent environment. Particulate matter smaller than 10 µm in diameter (PM10) is also associated with human health problems. Dust emission strength depends on the composition of granular material, road moisture, relative humidity, local climate (precipitation, wind velocity, etc.), and vehicle characteristics. The objectives of this study were to develop a reliable and rapid mobile methodology to measure dust concentrations on gravel roads, evaluate the precision and repeatability of the methodology and correspondence with the currently used visual assessment technique. Downwind horizontal diffusion was studied to evaluate the risk of exceeding the maximum allowed particulate matter concentration in ambient air near gravel roads according to European Council Directive [European Council Directive 1999/30/EC of 22 April 1999 relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Official Journal of the European Communities. L163/41.]. A TSI DustTrak Aerosol Monitor was mounted on an estate car travelling along test sections treated with various dust suppressants. Measured PM10 concentrations were compared to visual assessments performed at the same time. Airborne particles were collected in filters mounted behind the vehicle to compare the whole dust fraction with the PM10 concentration. For measuring the horizontal diffusion, DustTraks were placed at various distances downwind of a dusty road section. The mobile methodology was vehicle and speed dependent but not driver dependent with pre-specified driving behaviours. A high linear correlation between PM10 of different vehicles makes relative measurements of dust concentrations possible. The methodology gives continuous data series, mobility, and easy handling and provides fast, reliable and inexpensive measurements for estimating road conditions to make road maintenance more efficient. Good correlations between measured PM10-values, visually assessed dust generation and dust collected in filters were obtained. PM10 seems to be correlated to the whole dust fraction that impairs visibility on gravel roads. A decay in PM10 concentration as a function of distance from the road was observed. Measured particles principally did not travel further than 45 m from the road. The risk of exceeding the PM10 concentration stated in the EC-directive seems small.