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In many developing countries, roads start their lives as footpaths. These paths later develop into vehicle tracks, engineered natural surfaces, gravel roads and, eventually, bituminous roads. This paper is concerned with the stage of transition of roads from gravel to bituminous standard. This transition is common in many countries that have gravel roads as a significant proportion of the road network. On many gravel roads, it is not uncommon to find particles larger than 40 mm in the gravel matrix. During upgrading of a gravel road to a bituminous standard, it is common to incorporate some of the existing gravel layer in the new pavement. A dynamic cone penetrometer (DCP) is frequently used to assess the strength of the existing gravel layer. However, if the pavement being tested contains a high proportion of large and coarse gravels, a DCP will produce highly variable results. The issue therefore is how to assess adequately the strength of the existing layer in order to produce a more cost-effective pavement design. This paper proposes a method of combining deflection and DCP tests for an effective pavement design.

Sweden has a wide network of gravel roads. When the water table levels rise during the freeze-thaw and wet seasons, the bearing capacity of the roads will decrease and rut depths increase. The road will suffer a small deterioration every time a vehicle travel over it. Therefore, it has been decided to investigate the long-term performance of a Swedish designed gravel road using an accelerated pavement testing facility. A trial gravel road was constructed and exposed to various levels of ground water table which simulate the weather changes in Sweden. The structure of the trial gravel road consisted of 15 cm (base and surface layer), 20 cm sub-base layer and 260 cm subgrade soil. The trial road was tested using the Heavy Vehicle Simulator (HVS) and the vertical surface deformations and the vertical dynamic deformations were measured by means of laser profile measurement and eMU coils respectively. At the end of 85 000 HVS passes, the tested road suffered from serious deformations as discussed in details in this paper. Furthermore, a transverse trench section was excavated at the end of HVS trafficking in order to investigate the possible mechanism contributing to the tested road failure.

This study presents the performance of a trial gravel road subjected to HVS (Heavy Vehicle Simulator) trafficking in a compressed time period. The road structure was constructed with 150 mm-thick aggregate base course, and 125 mm-thick sub-base course. The test road responses, such as surface deformation and rutting were recorded using laser profile measurement instrument while the unbound layers’ dynamic deflections and strains data were periodically recorded at different depths during the execution of the test by means of an array of micro strain gauges. The test road was also instrumented with Water Content Reflectometers to record the changes in moisture contents in the road layers caused by the raising of the water table level under HVS trafficking. A total number of 85,000 HVS passes were applied to the trial gravel road structure under near-optimum as well as partially submerged subgrade moisture conditions. The test results emphasize the fact that the partial soaking of the subgrade soil by raising the groundwater table level caused a serious damage to the tested gravel road, as further detailed in this paper.

This paper presents a mobile robot prototype used for mallard navigation in a paddy field. One shortcoming of rice-duck farming is that a flock of mallards tends to gather in a specific area that produces a spring pond. This study was designed to develop a prototype of an autonomous mobile robot that guides a mallard flock to achieve highly efficient rice-duck farming. We developed a robot and waterproof boxes used for the protection of electric devices, including motors. The robot body is 270 mm long, 210 mm wide, and 250 mm high. Its body width is less than the length between rice stalks. After checking the waterproof capability for the body waterproof box, we conducted an indoor driving test for manual operation. Moreover, we conducted an outdoor evaluation tests to assess running on a gravel road and on a snowy road. We evaluated the robot performance not only for uneven surface roads including steps, but also for the range of wireless communication for controlling the robot.

In the northern Great Plains, a potential road dust abatement is the application of oil-well produced water, also known as “brine.” However, little is known about the effectiveness of brine or its potential impacts on dispersion of road materials and the creation of dusts. This study aimed to investigate how sodium adsorption ratios (SAR), electrical conductivity (EC), and Ca/Mg ratios of simulated and non-simulated brine influenced dispersive reactions of three mineralogically different gravel road fine fractions. Ca/Mg ratios had little to no significant influence on the outcome of dispersion. Irrespective of the SAR or clay mineralogy, a threshold EC of 4 dS m−1 was sufficient to control road fine fraction dispersion. Actual oil-well produced water effect on dispersion followed the same order as that treated by simulated solution and the dispersion value can be well-predicted from EC. This information is useful to managers, regulators, scientists, and industry professionals considering the use of brine as a road dust control abatement.

Rural accessibility is the only metric used in the Sustainable Development Goals to track progress toward better transport services in low- and middle-income countries. This paper estimates the rural accessibility index, defined as the proportion of the rural population who live within 2 kilometers of an all-season road, in 166 countries using open data. It then explores the cost of increasing the rural accessibility index in 19 countries, using an algorithm that prioritizes rural roads investments based on their impact on rural access and connectivity. Investment costs quickly balloon as the rural accessibility index increases, questioning the affordability of universal access to paved roads for many countries by 2030. If countries spent 1 percent of their gross domestic product annually on the upgrade of rural roads, even under optimistic assumptions on growth of gross domestic product, rural accessibility would only increase from 39 to 52 percent by 2030 across all developing countries. Alternative solutions to rural integration must thus be implemented in the short run until countries can afford to increase significantly access to all weather roads. For example, drones that supply regular food and medicine supply to remote communities are much more affordable than roads in the short term.

I arbetet har kalciumklorid respektive magnesiumklorid utvärderats i kombination med fyra olika finmaterial (granit, amfibolit, metagråvacka samt naturlig silt) vilka används vid underhåll av grusvägar. Vattenlösningar av respektive salt har tillförts finmaterialet varefter regn och upptorkning har simulerats i laboratoriemiljö. Utvärdering har gjorts med avseende på mängden kvarvarande salt efter regnsimulering samt svepelektronmikroskopi (SEM) och optisk mikroskopi på finmaterialet efter upptorkning. Det har varit svårt att dra några slutsatser. Den framtagna försöksmetodiken har inte kunnat påvisa agglomerering i finfraktion av grusslitlager eller ge ledning till doseringsråd. Man kan se att kalciumklorid är effektivare per giva än magnesiumklorid. Det krävs mindre mängd salt (flingor) för att binda en viss mängd vatten med kalciumklorid än med magnesiumklorid vilket dock är känt sedan tidigare. Agglomerering kunde inte bevisas med upprepade försök. Kemiskt var det ingen större skillnad, salterna betedde sig snarlikt och enligt tidigare känt beteende. Skillnader av beteende beroende på typ av bergmaterial var försumbart i förhållande till salternas inverkan. Den allra största delen (som minst 80 %) av tillfört salt har lakats ur efter regnsimulering. Ingen skillnad mellan kalcium- och magnesiumklorid eller de olika finmaterialen kunde konstateras avseende urlakning. En liten skillnad mellan urlakning av katjoner och anjoner kunde konstateras där katjonerna hölls kvar i finmaterialet. Detta kan röra sig om en jonbytareffekt. Analys med SEM och optisk mikroskopi kunde inte påvisa några egentliga skillnader mellan de olika kombinationerna av salt respektive finmaterial. Vid upptorkning av finmaterialet kunde konstateras att kalciumklorid, räknat som handelsvara, kan absorbera mer vatten än magnesiumklorid. Denna effekt kvarstod även efter att regnsimulering har utförts. Den metod som utvecklades i samband med arbetet gav inga påvisbara skillnader, som inte var kända sedan tidigare, mellan de olika salterna och finmaterialen. Troligen har systemet förenklats så långt att relevanta parametrar tagits bort eller inte reflekterar verkliga fältförhållanden. In this study, calcium chloride and magnesium chloride have been evaluated in combination with four different fine materials (granite, amphibolite, meta greywacke and naturally occurring silt), which are used for gravel road maintenance. Aqueous solutions of the two salts have been added to the fine material where after rain and drying has been simulated under laboratory conditions. Evaluation has been performed in terms of residual amount of salt after rain simulation, and SEM and optical microscopy on the fine material after drying, respectively It has been difficult to draw any conclusions that would yield new information from the tests. The methodology developed was not able to show agglomeration in the fine fraction of the gravel road material and it was not possible to provide recommendations regarding the dosage of dust binding agents. The tests show that calcium chloride is more efficient in retaining moisture than magnesium chloride when the comparison is based on the amount of flakes used. Agglomeration could not be proven despite several repeated tests. The chemical properties did not differ significantly, the salts behaved similarly and according to earlier known data. Differences in the origin of rock material was negligible compared with the effects of the salts. The added salt was for the most part (with a minimum of 80%) leached out during the rain simulation. No differences between calcium chloride and magnesium chloride or between the different fine materials were observed in terms of leaching. A small difference between leaching of cations and anions was recorded where the cations were retained in the fine material. This might be an ion-exchange effect. Analysis with SEM and optical microscopy did not yield any significant differences between the different combinations of salt and fine materials, respectively. During drying of the fine material it was observed that calcium chloride, calculated as commercial product, could absorb more water than magnesium chloride. This effect persisted also after the rain simulation. The experimental method that was developed during the study did not give any, previously not known, differences between the different salts and fine materials. Probably the system has been simplified to such an extent that relevant parameters were removed or do not reflect real field conditions.

Elongated landscape features like forest edges, rivers, roads or boundaries of fields are particularly salient landmarks for navigating animals. Here, we ask how honeybees learn such structures and how they are used during their homing flights after being released at an unexpected location (catch-and-release paradigm). The experiments were performed in two landscapes that differed with respect to their overall structure: a rather feature-less landscape, and one rich in close and far distant landmarks. We tested three different forms of learning: learning during orientation flights, learning during training to a feeding site, and learning during homing flights after release at an unexpected site within the explored area. We found that bees use elongated ground structures, e.g., a field boundary separating two pastures close to the hive (Experiment 1), an irrigation channel (Experiment 2), a hedgerow along which the bees were trained (Experiment 3), a gravel road close to the hive and the feeder (Experiment 4), a path along an irrigation channel with its vegetation close to the feeder (Experiment 5) and a gravel road along which bees performed their homing flights (Experiment 6). Discrimination and generalization between the learned linear landmarks and similar ones in the test area depend on their object properties (irrigation channel, gravel road, hedgerow) and their compass orientation. We conclude that elongated ground structures are embedded into multiple landscape features indicating that memory of these linear structures is one component of bee navigation. Elongated structures interact and compete with other references. Object identification is an important part of this process. The objects are characterized not only by their appearance but also by their alignment in the compass. Their salience is highest if both components are close to what had been learned. High similarity in appearance can compensate for (partial) compass misalignment, and vice versa. Fil: Menzel, Randolf. Freie Universität Berlin; Alemania Fil: Tison, Lea. Freie Universität Berlin; Alemania Fil: Fischer-Nakai, Johannes. Goethe Universitat Frankfurt; Alemania Fil: Cheeseman, James. University of Auckland; Nueva Zelanda Fil: Balbuena, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina Fil: Chen, Xiuxian. Freie Universität Berlin; Alemania Fil: Landgraf, Tim. Freie Universität Berlin; Alemania Fil: Petrasch, Julian. Freie Universität Berlin; Alemania Fil: Polster, Johannes. Freie Universität Berlin; Alemania Fil: Frau Verbauwede, Anabel Maria. Freie Universität Berlin; Alemania

The road sector in Ethiopia continues to develop its road network throughout the country at a tremendous rate with the aim of connecting all kebeles (administrative districts) to nearby higher class roads using all-weather gravel road solutions. These should provide access to the rural areas where most of the country's population is found, by means of the universal rural road access program (URRAP). Currently, Ethiopia is constructing many URRAP road projects which are susceptible to defects and there is not enough study that addresses the frequent causes. This study investigated the nature and causes of defects based on extensively reviewed literature, questionnaire responses, site visits and design reviews on two selected road projects, as well as in an interview with professionals. The major defects identified are poor vertical alignment and excessive road gradient, stoniness of the surface, inconsistency of road character without warning signs, poor drainage elements and aggregate loss. It was concluded that the lack of a prompt payment system, an ineffective project management system, inadequate and experienced human resources on the owner side, together with design error and omissions and insufficient data for design and construction in predicting underground conditions were some of the critical factors causing defects. The major causes of defects were shared 40 % by the consultant and 60% by the client.

The rural population of India lack adequate transport infrastructure to access the nearby towns/headquarters. The Ministry of Rural Development (MoRD), Government of India (GoI) decided to develop various rural roads under Pradhan Mantri Gram Sadak Yojna (PMGSY). The main objective of PMGSY is to achieve all weather connectivity to all habitations. Hence, a pilot study was initiated over a 7 km gravel road stretch from “Ghanapur-Palakurthy Public Works Department (PWD) Road to Komatigudem via Ippagudem, and Rangaraigudem” in the Warangal district of Telangana State, India. There are various disadvantages associated with construction using gravel like dust generation and gravel loss over a period of time due to passage of vehicles. The best solution to minimize these problems is to seal the gravel roads. The pilot road considered in this study was constructed using locally available gravel up to the surface course and then sealed using surface dressing. The performance of the road sections were evaluated in terms of roughness, skid resistance, and texture depth. The initial set of data was collected immediately after construction and one month after construction. Later, four sets of pavement performance data was collected after seven months of construction of the surface dressing layer in November 2013, January 2014, April 2014, and June 2014. Altogether, six sets of data were collected. The data was analyzed and important observations are reported in this paper. There is a considerable change in surface texture and skid resistance values after the first one month of construction whereas no significant changes were observed in the roughness values. Further, there is no significant difference in the results of surface texture, skid resistance and roughness values when the pavement sub-sections were evaluated for four times even after seven months of construction of the sealing layer.

The Arba Rekete-Gelemso gravel Road section is affected by the presence of expansive soil, this soil has shrinking and swelling behavior due moisture fluctuation. The main objective of this research work is to investigate the Characterization of Borrow materials for embankment fill and capping layer based on their index and strength properties for Road Construction of the proposed route. In order to achieve the objectives, field investigation and nine (9) samples were also collected from the identified borrow area and laboratory test analysis were performed such as, Atterberg limits, compaction, CBR and percentage of swell tests. ERA‘s and AASHTO’s standard technical specifications have been used to interpret the data by integrating the field with laboratory test results. The subgrade soil of route, having liquid limit value greater than 60% and plastic index value greater than 30% and CBR value less than 5%, at Chainage km 0+000-4+000, 5+900-8+000, 9+400-12+900, 13+500-14+000, 15+000-16+000, 17+100-17+600, 18+500-20+500, 21+500-34+900, and 35+200-47+000 unsuitable. The index and strength properties of the borrow materials fulfill the requirement for embankment fill and subgrade improvements. Finally, all unsuitable subgrade soil along the study route corridor are recommended to remove and replace with suitable and non-expansive subgrade materials, since enormous amount of selected fill materials that fulfill the requirements for subgrade soils improvement are available nearby the study area.

The following paper presents results of research carried out on oiled gravel aggregate. In Russia, the oil-treated aggregate mixture is called “loose-bound organic-mineral mixture” (hereinafter abbreviated as LOM). The aim of the research was to explore the possibility of using oil waste products and their heavy residues generated during oil transportation as a binder in oil-treated gravel aggregate or LOM. Currently, this waste is not used anywhere, it is widely burned, polluting the environment. Studies were carried out using Infra-red spectroscopy of samples of the original oil waste, heavy residues of oil waste and road oil bitumen of BND 90/130 quality type. The fractional composition of oil wastes and their heavy residues was studied during their distillation by heating to a temperature of +335 °C. It was found that for preparing LOM it is more effective to use oil residues. The number of LOM compositions samples were prepared and their main physical and mechanical indicators were determined. Based on the tests, it was concluded that the residues of oil waste can be used as a binder in the composition of LOM such as oil-treated gravel.

We focus on rally drivers’ eye movements and behaviors when they are driving around a corner on a gravel road in this research. Recent studies of visual strategy regarding visual control in driving have been conducted in a driving simulator and on a racing course or paved roads. However, this study was conducted in the real environment of gravel roads and with real vehicles. In this study, the difference between the accomplished and intermediate rally driver’s eye movements and fixation points were defined. The study’s purpose was to understand how expert drivers move their eyes while driving around a corner on a gravel road. Twelve subjects, who were rally drivers in Japan, participated in the experiment; the accomplished driver had won the World Rally Championship (WRC) and was the fast rally driver in Japan. Each subject’s eye movement was measured with mobile eye tracker (Tobii Pro Glasses 2, Tobii, Sweden) and operated at 50 Hz. The eye tracker recordings were analyzed using Frame-By-Frame analysis. This study suggests that the eye movements of accomplished drivers allow them to control the car safely and be conscious of oncoming corners. Furthermore, by looking and thinking ahead like accomplished drivers, the cognitive load associated with driving is likely to decrease; furthermore, it may serve to activate their memories of previous rallies.

Rural access is among the most important infrastructure constraints in rural Africa. Using the results from comprehensive household surveys and other data from Ethiopia, the paper recasts light on the heterogeneous impacts of road accessibility on agriculture and nonagricultural growth. It is found that crop production is increased by major and feeder road improvements. Significant synergy is also found. When investigating further into this effect, there are two impacts: farmers' access to the input market, especially fertilizer, was improved mainly by major corridor improvement. And output market access was improved by feeder road improvement. In addition, the household's nonagricultural income is somehow increased by improved road connectivity. There must be secondary effects. The transport demand function estimated with additional data indicates that as the road network improves, people's mobility increases. Furthermore, local business employment is found to increase with road improvements. To meet the increasing demand for mobility, efficiency and frequency of transport services are important.

This paper presents a methodology to identify key priority areas for transport investments. The methodology uses a geospatial data-driven approach and then proposes an innovative economic analysis for project appraisal. The two main steps involve (i) prioritization of road interventions based on a set of economic, social, and risk reduction criteria; and (ii) assessment of monetized and nonmonetized costs and benefits of road interventions under many scenarios covering the uncertainty on future risks and other factors. This methodology is used at different stages of project preparation for a rural roads lending operation to the Government of Mozambique. In the two regions of Mozambique considered, the analysis prioritizes regions along the coast when combining agriculture, fisheries, poverty, network criticality, and hazard risk criteria. With a limited budget of US$15 million per district, the results show that investing in repairing and rehabilitating culverts and bridges is the intervention that performs better under most of the scenarios.

Durante las negociaciones de La Habana y en la fase inicial del pos- conflicto, se ha reconocido que una infraestructura vial que permita la transformación del campo y acerque el Estado a las comunidades rurales para proveerlas de servicios sociales fundamentales, como salud, vivienda y educación, y que promueva actividades económicas lícitas y el desarrollo de proyectos productivos, es una de las herramientas esenciales para la construcción de una paz estable y duradera. En este ámbito, las facultades de ingeniería civil tienen un papel preponderante, no solo para pronunciarse sobre aspectos técnicos relacionados con el mejoramiento, la conservación o la construcción de vías en la red terciaria, sino también para que sus estudiantes, desde su proceso de formación, conjugando lo académico con lo práctico, se conviertan en agentes activos en el posconflicto y generadores de cambio. Con esta perspectiva, el Semillero de Investigación en Pavimentos de la Escuela Colombiana de Ingeniería Julio Garavito hizo el trabajo que se presenta en este artículo, en el que, aplicando el método Viziret evaluó el estado de las superficies de vías, con el fin de proponer soluciones para la intervención, en tramos de la red vial terciaria de los departamentos de Santander y Boyacá que pasan por los municipios de Jesús María, La Belleza, Florián y Saboyá. En términos generales, se concluye que el estado de las vías transita- das es el resultado de condiciones ambientales y topográficas que no hacen viable la solución de afirmado como superficie de rodadura y que, aun si se cumpliera con las especificaciones de materiales y se llevarán a cabo actividades de mantenimiento en las vías, este tipo de solución continúa siendo insostenible para los niveles de precipitación y gradientes topográficos que se presentan en la zona., During the Colombian peace process in Havana and the initial phase of the post-conflict, it has been recognized that a road infrastructure that allows the transformation of the countryside and brings the gov-ernment closer to rural communities to provide them with basic social services such as health, housing, and education, that also promotes licit economic activities and the development of productive projects, is one of the essential tools for building a stable and lasting peace. In this area, civil engineering faculties have a preponderant role, not only in technical aspects related to the improvement, conservation or con-struction in the tertiary road network, but also so that their students, from their training process, combining academia and practice, become active agents in the post-conflict and generators of change. With this perspective, the Pavement Research Seedbed from Escuela Colombiana de Ingeniería Julio Garavito performed the activity presented in this article, in which applying the Viziret method, made the evaluation of the surface conditions in part of the tertiary road network, from which solutions are proposed for their intervention, in the departments of Santander and Boyacá, that crosses through the municipalities of Jesús María, La Belleza, Florián, and Saboyá. In general, it is concluded that the condition of the evaluated routes is the result of environmental and topographical conditions that do not make the gravel road solution viable as a surface road and that, even if material specifications were met and activities of maintenance on the road is made, this type of solution remains unsustainable for the precipitation levels and topo-graphic gradients that occur in the area., 1. Estudiante de Ingeniería Civil, líder del Semillero de Investigación en Pavimentos (semestre 2018-1) de la Escuela Colombiana de Ingeniería Julio Garavito. 2. Profesora titular, directora del Centro de Estudios Geotécnicos y tutora del Semillero de Investigación en Pavimentos de la Escuela Colombiana de Ingeniería Julio Garavito. leidy.benitez@mail.escuelaing.edu.co - sandra.campagnoli@escuelaing.edu.co

Increased traffic flow on low-volume gravel roads and deficiencies of national road infrastructure, are increasingly apparent in Lithuania. Gravel roads do not comply with requirements, resulting in low driving comfort, longer travelling time, faster vehicle amortization, and dustiness. The control of dustiness is one of the most important road maintenance activities on gravel roads. Another important issue is the assurance of required driving comfort and safety. Soft asphalt and Otta Seal technologies were proposed as a sustainable solution for the improvement of low-volume roads in Lithuania. Five gravel roads were constructed with soft asphalt, and 13 gravel roads were sealed with double Otta Seal, in 2012. The main aim of this research was to check soft asphalt and double Otta Seal’s ability to self-heal, on the basis of the results of the qualitative visual assessment of pavement defects and distress. The qualitative visual assessment was carried out twice a year following the opening of the rehabilitated road sections. The results confirmed soft asphalt and double Otta Seal’s ability to self-heal. The healing effect was more than 13% and 19% on roads with soft asphalt and double Otta Seal, respectively. In addition, on some roads, all cracks observed in spring self-healed during summer.

One of the main objectives for vehicle designers is to achieve flat, safe ride in any environmental conditions. When a vehicle is moving along the road it is exposed to vibrations in multiple axes and directions. Vehicle behavior is extensively investigated in reference to road imperfections that could be expressed as single step disruptions, like remote bumps on the road. A simulation model, previously designed, was already used to investigate vehicle behavior, when riding over the step inputs. This model is further upgraded and now can perform simulations of the scenarios when vehicle is subjected to continuous imperfections on the road, like long runs of the gravel road in the country areas. Vehicle behavior is analyzed for few, common, speed levels in such scenarios. We can achieve lover amplitudes of pitch vibrations driving with the certain speed, but far the best outcome is obtained when active suspension is applied.

The occurrence of 36 arable weed species across 13 counties in the eastern Arkansas–Mississippi Delta area on 489 randomly selected road sites was surveyed in 2012. Palmer amaranth, johnsongrass, large crabgrass, barnyardgrass, prickly sida, and broadleaf signalgrass were the top six weed species, with occurrence noted at 313, 294, 261, 238, 176, and 136 sites, respectively. Factors found to affect weed occurrence along Mississippi Delta roadsides included topographical characteristics, weed species, ditch slope, road type, and nearby land use. Among roadside topographical characteristics, road shoulder was found to strongly affect weed occurrence. In addition, paved and gravel road types with moderate roadside slope explained most of the variability of weed occurrence at each sampling site. Additionally, nearby arable land use affected weed occurrence more so than natural, residential, and pastoral land. Barnyardgrass, johnsongrass, and Palmer amaranth were 3.6 to 4.3 times more likely to occur than all other species identified. An effective weed management plan along eastern Arkansas–Mississippi Delta roadsides should focus on road shoulder, adjacent arable land use, road type, and specific weed species (e.g., Palmer amaranth, johnsongrass, and barnyardgrass). The inclusion of these parameters in future weed control programs can prove invaluable for preventing the spread of the herbicide-resistant Palmer amaranth, barnyardgrass, and johnsongrass.

Running or developing the local MMS or PMS, be it for unsealed or sealed pavements, needs a team of well-trained and experienced road organization staff and appropriate equipment. The data employed to run a gravel roads MMS should reflect the capacity of the road organization personnel to collect them. In this regard, the team should be of adequate size, education and experience. It is, therefore, essential for the benefit of road users, road organization, the environment, and the sustainability of gravel roads to establish the capacity of road organization personnel responsible for running gravel road maintenance management with the intention of meeting social, economic, and political demands.The need to establish the adequacy of Tanzania road organizations in running gravel road MMS and PMS was the reason for conducting the qualitative research aspect of this study. The survey also intended to find out which parameters are readily collected by the surveyed road organizations, so as to include them as variables in formulating a gravel loss prediction model.This paper presents analysis and discussion of the questionnaire responses. The study notes the challenges being faced by road organizations responsible for the maintenance management of gravel road network in Tanzania and attempts to map a way forward.

Gravel road dust has significant health effect. The study was conducted to assess road dust suppression effect of molasses stillage in gravel at a Sugarcane Estate in Zimbabwe. Three, 2 km long gravel road sections (steep, sloping and gentle) had the following dust suppression treatments applied to 500m long segments: (i) molasses stillage, (ii) water and (iii) control. Data on dust deposition rates were subjected to Analysis of Variance (ANOVA) to compare treatment means. Mean road dust deposition rates ranged from 998.46±50.04 to 6184.02±257 mg/m

Recently, electrical welfare vehicles with free casters are widely used by patients and elders indoors. However, welfare vehicles may not be able to move well on gravel or dirty roads as seen in suburbs. In order to expand driving area, the skid steer mechanism is focused on. The skid steer vehicle (SSV) has been used for its high traveling ability on rough road. However, the SSV has disadvantage that the driving assistance is required because its steering is highly affected by road conditions. In this paper, a driving assistance control of SSV using the model error compensator and state estimator, i.e. EKF and cornering power estimator is proposed. The maneuverability is evaluated by correlation coefficient of joystick operation comparing asphalt road and gravel road.

Rural access is among the most important infrastructure elements to stimulate economic growth in rural and remote areas. The sustainability of feeder road maintenance is a challenge in many developing countries. Many feeder roads are unpaved and need to be maintained frequently, but they are often neglected under budget pressure. Output- and performance-based road contracts are an instrument to ensure the sustainability of road maintenance. Contractors are required not only to improve roads, but also to maintain them. Using micro data from household surveys in Zambia, the paper examines the impacts of output- and performance-based road contracts on agricultural production. It shows that the contracts have a significant impact on crop production, especially maize and groundnuts, two major crops grown in the study area. The paper also finds that the measured impacts are associated with actual road maintenance works, regardless of contractual methods. Any road work can improve people's connectivity, even if it is not an output- and performance-based road contracts. The impact of the contracts is catalytic: more road works were implemented on contract roads than non-contract roads, holding everything else constant. This is an important contribution to the sustainability of road maintenance. Finally, road improvement works are found to facilitate farmers' market participation, but the impact seems weak. There may be other constraints. Transport service costs are found to have a negative impact on farmers' market sales. Thus, although roads are improved, transport services may be not available or too expensive, which still hamper farmers' market participation.

Road transport is one of the biggest soil polluter. There are a lot of investigations of soil pollution near highways, but soil pollution near gravel roadsides needs more experimental research. In this experimental study we selected gravel road Juseviciai – Būdvietis – Derviniai and analyzed soil pollution near this road. Soil samples were collected on both sides of the road by making the transversal profile, the sampling points move away of the road at a distance 1; 2; 5; 10 meters, the samples were collected in 600 meters long strip. All samples were collected by using the envelope principle, samples were taken from the top of the soil layer 0 - 10 cm depth. It was established that Mn concentration in the soil sample, which was taken from the middle of gravel road carriageway, reached 238,5 mg/kg – it means 1,79 times less than background value. This value is more than 6 times less than maximum allowed concentration and quit close to the values, which were established on both sides in the soil close to gravel road. The modelling of Mn concentration where made in appropriate scale of mathematical model – 15 meter to both sides of gravel road, the width of the road – 4 meters. The simulated soil volume is 34 x 14 meters, the soil type - medium-coarse sandy loam. It was modeled that after one year Mn concentration in the soil, close to gravel road remains 1,8 times less than background value (at a constant Mn emission in the environment). Moving away from driveway till 10-15 meters the concentration of Mn decrease to 2,48 less in the soil depth of 0,5 m. After 10 years this concentration will reach 1 meter depth. Bet there would be no changes of Mn concentration in the groundwater level. DOI: https://doi.org/10.3846/enviro.2017.036

As South Africa moves further away from the political transition of 1994, the economic history of the post-apartheid era is coming up for debate. The optimism generated by the ANC’s early successes must now, after more than two decades of democracy, be tempered by its conspicuous failures. Not all is lost, though. African growth, technological innovation and private-sector participation in public sector services offer credible opportunities for accelerated development, but will only be effective if policy-makers are cognizant of the political realities. The long walk to economic freedom for many will, unfortunately, continue along a rocky gravel road.

Roughness is a dynamic property of the gravel road surface that affects safety, ride comfort as well as vehicle tyre life and maintenance costs. A rapid survey of gravel road condition is fundamental for an effective maintenance planning and definition of the intervention priorities.Different non-contact techniques such as laser scanning, ultrasonic sensors and photogrammetry have recently been proposed to reconstruct three-dimensional topography of road surface and allow extraction of roughness metrics. The application of Microsoft Kinect™ depth camera is proposed and discussed here for collection of 3D data sets from gravel roads, to be implemented in order to allow quantification of surface roughness.The objectives are to: i) verify the applicability of the Kinect sensor for characterization of different forest roads, ii) identify the appropriateness and potential of different roughness parameters and iii) analyse the correlation with vibrations recoded by 3-axis accelerometers installed on different vehicles. The test took advantage of the implementation of the Kinect depth camera for surface roughness determination of 4 different forest gravel roads and one well-maintained asphalt road as reference. Different vehicles (mountain bike, off-road motorcycle, ATV vehicle, 4WD car and compact crossover) were included in the experiment in order to verify the vibration intensity when travelling on different road surface conditions. Correlations between the extracted roughness parameters and vibration levels of the tested vehicles were then verified. Coefficients of determination of between 0.76 and 0.97 were detected between average surface roughness and standard deviation of relative accelerations, with higher values in the case of lighter vehicles.

Terrestrial reconnaissance in the border provinces in Thailand is very risky and dangerous mission for troops and government officers. Many of troops were killed and injured by the incendiary bombs buried in the roads. In order to preventing the loss of life and property damages, many inventions of bomb detector have been commercially used such as GPR (Ground Penetration Radar) and REST (Remote Explosive Scent Tracing). Unfortunately, these technologies are expensive and inappropriate in some situations. This paper presents the forthcoming technology of the real-time image recognition for terrestrial reconnaissance. By using the road texture analysis in image analytic, the data set of normal surfaces of the road (e.g. asphalt road and gravel road) will be trained as the prior-knowledge. The system can compare the buried surface with the normal surface of the road and warning the troops beforehand.

An accelerated corrosion test, known as proving ground accelerated test, is commonly performed by automotive manufacturers to evaluate the corrosion performance of a vehicle. The test combines corrosion and durability inputs to detect potential failures that may occur during in-service conditions. Currently, the test is conducted at an external test center overseas. Such test is aimed to simulate the effects of one year accelerated corrosion in severe corrosive environment of the north-east and south east of America. However, the test results obtained do not correlate with the actual corrosion conditions observed in the Malaysian market, which is likely attributed to the different test environment of the tropical climate of vehicles in service. Therefore, a vehicle accelerated corrosion test procedure that suits the Malaysian market is proposed and benchmarked with other global car manufacturers that have their own dedicated corrosion test procedure. In the present work, a test track is used as the corrosion test ground and consists of various types of roads for structural durability exposures. Corrosion related facilities like salt trough, mud trough and gravel road are constructed as addition to the existing facilities. The establishment of accelerated corrosion test facilities has contributed to the development of initial accelerated corrosion test procedure for the national car manufacturer. The corrosion exposure is monitored by fitting test coupons at the underbody of test vehicle using mass loss technique so that the desired corrosion rate capable of simulating the real time corrosion effects for its target market.

It is proposed to determine the velocity of the embedded mobile robot in a real world test environment .The test environment considered in this work is the man-made road surfaces like cement road surface, sand road surface, Bituminous Thar road surface, Grass road surface and loose gravel road surfaces etc. First, fuzzy logic control of velocity estimation a mobile robot is done using Matlab for the different surfaces. Then the real time tests on the different surfaces were carried out. The simulated values are compared with the test values. The comparison showed that the simulation values were close to the real time test values.

Vehicle mass is an important parameter in vehicle dynamics control systems. Although many algorithms have been developed for the estimation of mass, none of them have yet taken into account the different types of resistance that occur under different conditions. This paper proposes a vehicle mass estimator. The estimator incorporates road gradient information in the longitudinal accelerometer signal, and it removes the road grade from the longitudinal dynamics of the vehicle. Then, two different recursive least square method (RLSM) schemes are proposed to estimate the driving resistance and the mass independently based on the acceleration partition under different conditions. A 6 DOF dynamic model of four In-wheel Motor Vehicle is built to assist in the design of the algorithm and in the setting of the parameters. The acceleration limits are determined to not only reduce the estimated error but also ensure enough data for the resistance estimation and mass estimation in some critical situations. The modification of the algorithm is also discussed to improve the result of the mass estimation. Experiment data on a sphalt road, plastic runway, and gravel road and on sloping roads are used to validate the estimation algorithm. The adaptability of the algorithm is improved by using data collected under several critical operating conditions. The experimental results show the error of the estimation process to be within 2.6%, which indicates that the algorithm can estimate mass with great accuracy regardless of the road surface and gradient changes and that it may be valuable in engineering applications. This paper proposes a recursive least square vehicle mass estimation method based on acceleration partition.

Measurement of particle-size distribution (PSD) of soil with large-sized particles (e.g., 25.4 mm diameter) requires a large sample and numerous particle-size analyses (PSAs). A new method is needed that would reduce time, effort, and cost for PSAs of the soil and aggregate material with large-sized particles. We evaluated a nested method for sampling and PSA by comparing it with the methods that follow the American Association of State Highway and Transportation Officials (AASHTO) standard T88-00 and the American Society for Testing and Materials (ASTM) standard D422-63. Using 33 forest road aggregate samples from the Clearwater National Forest in northern Idaho, the nested method required much less laboratory time and effort and resulted in similar PSA values, except for the 0.149 mm (No. 100) sieve, where the smallest particle-size fraction (PSF) values (1.30% and 1.39%) were observed. The nested method shows great potential for determining PSDs of the soil and aggregate material with large-sized particles and should be tested on other forest soils and road aggregates. The nested sampling and analysis method allows for the same number of samples to be collected but requires less laboratory time, making it more efficient and economical for testing the soil and aggregate material with large-sized particles such as forest road aggregate.

Gravel roads are majorly affected by deterioration which manifests as loss of gravel materials due to traffic and environmental conditions. District Road Maintenance Managers are faced with competing investment demands to maintain gravel road networks in the best condition due to inadequate intelligent techniques of evaluating the roadway performance. The aim of evaluating the road network performance is to reduce the rate of deterioration so that maintenance interventions could be extended. Road condition data is a precursor for road monitoring and is collected on a periodic basis by road authorities to assist in transportation planning. The primary objective of this paper was to evaluate and analysis the trend of Botswana gravel road condition which best captures the effects of gravel road condition influencing factors. This was achieved by carrying out exploratory statistical analysis. Gravel road condition data were collected through the Botswana Roads Department covering 2002, 2005 and 2008 for Botswana district gravel road networks. The variables required for the analysis were clustered and pre-processed to determine their suitability. The analysis results gave a broad overview of the extent to which gravel road condition trends lend credence to their usefulness in district transportation networks monitoring in Botswana.

Throughout their recent recovery in several industrialized countries, large carnivores have had to cope with a changed landscape dominated by human infrastructure. Population growth depends on the ability of individuals to adapt to these changes by making use of new habitat features and at the same time to avoid increased risks of mortality associated with human infrastructure. We analyzed the summer movements of 19 GPS-collared resident wolves (Canis lupus L.) from 14 territories in Scandinavia in relation to roads. We used resource and step selection functions, including >12000 field-checked GPS-positions and 315 kill sites. Wolves displayed ambivalent responses to roads depending on the spatial scale, road type, time of day, behavioral state, and reproductive status. At the site scale (approximately 0.1 km2), they selected for roads when traveling, nearly doubling their travel speed. Breeding wolves moved the fastest. At the patch scale (10 km2), house density rather than road density was a significant negative predictor of wolf patch selection. At the home range scale (approximately 1000 km2), breeding wolves increased gravel road use with increasing road availability, although at a lower rate than expected. Wolves have adapted to use roads for ease of travel, but at the same time developed a cryptic behavior to avoid human encounters. This behavioral plasticity may have been important in allowing the successful recovery of wolf populations in industrialized countries. However, we emphasize the role of roads as a potential cause of increased human-caused mortality., Lay Summary We studied how wolves in Scandinavia respond to roads built to ease human travel but degrading habitat quality for many wildlife species. Wolves responded with ambivalence: They both selected and avoided roads, all depending on the spatial and temporal scale and their behavioral status. To understand the multi-scale effects of human infrastructure on animal behavior is important with regard to the recent come-back of many wildlife species to now industrialized countries.

This study demonstrates the economic benefit analysis from two alternative project on gravel road surface using HDM-4 to access the most appropriate project and maintenance standard both in term of pavement remaining life and also road user cost (RUC). The two alternative projects will be treated with different work standards. First Alterative namely “Without Project” will only be maintain the existing project with grading every six months, spot re-gravelling to replace 30% of material lost each year, and gravel resurfacing. Second Alternative namely “With Project” will be maintaining and upgrading the existing road pavement to bituminous pavement in year 2019 for section A001-01 and for section A001-02 in year 2020, by doing grading every six months and spot re-gravelling to replace 30% of material lost each year. In conclusion, from two proposed alternatives, although it requires more funds at earlier stages ‘with project’ alternative is the most appropriate project considering the number of maintenance followed, overall road performance, RUC, and the values of NVP and IRR.

The Wyoming technology Transfer Center (WYT2/ LTAP) is currently in the process of developing a Gravel Roads Management System (GRMS) in Wyoming. One of the major components of this new GRMS is developing a comprehensive optimization methodology for Maintenance and Rehabilitant (M&R) activities. To support the new optimization methodology, this research study established multiple performance models to predict the deterioration patterns of gravel roads in Wyoming. Condition data, in addition to the average deterioration rates, for approximately 1931km (1200 miles) of gravel road segments were used to develop these models. A probabilistic modeling approach using Markov Chains (MC) was adopted in this study to establish these prediction models. The developed prediction equations obtained from fitting these models include all the possible deterioration modes of gravel roads such as potholes, washboards, loose aggregate, and rutting. Generally, it was found that the average service life of a gravel road is around 12 months without any maintenance intervention. In addition, potholes, rutting, and washboards are the main failure modes for these types of roads.

Excessive deformation of multi-layered road structure induced by vehicle traffic loading is one of the main reasons leading to pavement failure. In this paper, the elastic response and cumulative deformation of a multi-layered road structure under dynamic loads are investigated through experimental tests and theoretical analysis. First, a physical model with thin asphalt surfacing layer, cement stabilised gravel road base and layered decomposed granite soil subgrade is built to better understand the dynamic behaviour of a multi-layered road structure system. Experiments are performed to determine the elastic responses (vertical stress and displacement) and cumulative plastic deformation at different depths of road structures. A calculation method of the dynamic stiffness matrix is developed on the basis of an assembly process compatible with good numerical efficiency, and results from the calculations are verified using model experiment data. Then, the dynamic deviator stress is derived according to the dynamic stiffness matrix method and is used to formulate a cumulative deformation computational model considering both road infrastructure and its soft subsoil. Moreover, the cumulative deformation of a road on soft subsoil under repeated traffic load is analysed for different material properties of the road layers using the presented method.

We recorded 94 sound-response events at 3 adult-occupied northern goshawk (Accipiter gentilis) nests 78m, 143m, and 167m from the nearest United States Forest Service maintenance level 3, improved gravel road on the Kaibab Plateau in northern Arizona. During 4 test sessions on 7, 8, 10, and 11 June 2010, we recorded 60 experimentally controlled logging trucks; 30 non-experimental, civilian, fixed- winged aircraft; 3 non-experimental, passing cars; and 1 all-terrain vehicle (ATV). Logging truck sound, principally engine and exhaust, was concentrated in the 63Hz and 80Hz, 1/3-octave frequency bands. Aircraft sound was concentrated in the 100Hz and 125Hz, 1/3-octave frequency bands. Logging truck noise levels varied among nest sites and with distance from roads. At 167m from the closest road, the logging truck averaged approximately 8 decibels (dB, all decibel levels C-weighted, adjusted, 1s, equivalent sound level, CLEQ) quieter than aircraft. At 143m, the logging truck was approximately 3dB quieter than passing aircraft. Only at 78m was logging truck noiselouder on average than aircraft, by approximately 6dB. Average aircraft noise levels for each day of testing ranged between 45.6dB and 67.9dB and when averaged across the entire study period, varied little among the 3 test sites, 60.1-65.6dB. On average, our test logging truck (61.9dB) wasnolouderthanpassingaircraft (62.3dB),whichgoshawks generallyignored. The loggingtruck resulted in 27% no response and 73% alert (head turning) response, passing aircraft resulted in 90% no response and only 10% alert response, and the cars and ATV combined resulted in 50% each for no response and alert response. Goshawk alert response rates were inversely proportional to nest distance from the nearest road, decreasing from 91% to 57% alert between 78m and 167m. No movements or flushes were associated with either our experimental testing or passive recording of other vehicular noise stimuli. All tested pairs of goshawks successfully fledged young. Because logging truck noise had no effect on northern goshawks nesting along level 3, improved gravel roads on the Kaibab Plateau, restriction of log hauling and other road- based travel activities on similar roads within post-fledging family areas (PFAs) appears unnecessary based on the type and extent of our testing. 2013 The Wildlife Society.

Materials used to reduce dustiness on gravel roads affect both the gravel road surfacing and the neighbouring vegetation. Materials used to reduce dustiness may access vegetation directly (when sprayed on gravel roads) and indirectly (when leached out by precipitation). The investigation examined a new substance, the aqueous solution Safecote (of different concentrations) and its mixtures with calcium chloride. 10%, 20% and 30% concentrations of Safecote and 36.5% of calcium chloride were used. The mixture ratio was 1:1 by volume. The investigation addressed the impact of the applied solutions on the length and viability of the above-ground part of plants. The timothy grass, white clover and crimson clover species of grass vegetation were selected for the investigation. The choice was determined by the fact that these species frequently grow in pastures by gravel roads. As it was determined during the investigation the viability of the selected plants in non-contaminated soil was 85-89%, in soil contaminated with dust reducing agent was 67-88% using solution Safecote, and 0-1% when applying mixtures of solutions. After 6 weeks of growth the length of above-ground part was 6.41-8.57 cm in uncontaminated soil, 4.22-8.18 cm in soil contaminated with Safecote solution and 0.00-2.07 cm in soil contaminated with the mixture.

Botswana is a Southern African country with an area of about 582,000 sq. km and its small population of about 2 million people. The road transportation network has grown beyond all expectations since independence in 1966. Out of the 18,300 km Botswana Public Highway Networks, gravel road networks are significant in providing access to rural areas where the majority of the population lives. Modelling of gravel loss conditions are required in order to predict their conditions in the future and provide information on the manner in which pavements perform. Such information can be applied to transportation planning, decision making processes and identification of future maintenance interventions. The results of previous attempts to develop gravel loss condition forecasting models using multiple linear regression (MLR) approach have not been reliable. This paper intended to develop accurate and reliable performance models which best capture the effects of gravel loss condition influencing factors using Feed Forward Neural Network (FFNN) modeling technique. As extension of knowledge in unpaved road transportation network, FFNN trained with Levenberg-Marquardt (L-M) method was used to develop gravel loss performance prediction model for Botswana gravel road networks to achieve a reliable result of a higher coefficient of determinant R2 = 0.94 compared with MLR analysis of R2 = 0.74.

Recently, welfare vehicles are widely used by patients and elders indoors, and many welfare vehicles with free casters drive indoors. However, the vehicle with free casters may not be able to move well on gravel or dirty road as seen in rural yard. In order to expand driving area for welfare vehicles, it is necessary to apply a new mechanism on the rough road. To design compact welfare vehicles for outdoor use at low cost, the skid steer mechanism is focused on. The skid steer vehicle (SSV) has been used for its high traveling ability on rough road. However, the SSV has disadvantage that the maneuvering assistance is required because its steering is highly affected by road condition. This study aims a driving assistance of SSV for patients and elders by using Model Error Compensator (MEC) that suppresses the modeling error. The proposed controller consists of MEC, Extended Kalman Filter (EKF) that reduces sensor and system noise assuming the undulating and skiddy gravel road, and estimation of cornering power of SSV. The effectiveness of the proposed control system is confirmed by the outdoor driving experiment comparing asphalt and gravel roads.

220kV open type substation equipment's surface will readily accumulate industrial and natural filthy when they expose to outdoors in a long-term, and this situation will lead to the phenomenon of flashover. The Substation Water Washing Robot in this paper can transport the high pressure water jet equipment to the operating position by insulated telescopic boom, and then carry out water washing operation to substation insulators, surge arresters, electric equipment casing and others with the high purity water through RO reverse osmosis technology. robot can achieve a barrier-free travel in the area of substation outdoor road and grass or gravel road in the facilities religion with crawler mobile chassis; Using multistage combination insulation and insulated telescopic lifting arm structure to improve the stability of water flushing operation; Using wireless remote control to effectively reduce the intensity of manual work, improving the safety of operation and ensuring the operation safety.

Performance modelling of gravel roadways is required to predict the conditions in the future and provide information for optimal maintenance interventions. Roads are expensive asset and should be properly maintained regardless of their class or function to enhance their performance. Optimal maintenance interventions at the appropriate time to preserve the asset value are required. As improvement over previous methodologies, this paper modifies the logistic regression model by incorporating the ordinal nature of a dependent variable through defining the probabilities differently to develop improved gravel road performance models based on site specific data. The models reflect the history of gravel loss conditions to predict future performance for gravel roads in Botswana as a threshold to trigger optimal maintenance interventions. The input data for the models were generated from the triennial condition survey for Botswana carried out in 2002, 2005, and 2008. The developed improved gravel road performance methodologies are long term plans for preservation and maintenance as gravel road management systems in Botswana.

In developing countries like India, rural areas lack adequate transportation facilities. The Ministry of Rural Development (MoRD), Government of India (GoI) decided to develop rural roads under Pradhan Mantri Gram Sadak Yojana (PMGSY). The objective of this program is to achieve connectivity to all habitations under different climatic conditions. There are certain disadvantages associated with construction of the rural roads using gravel like dust generation, gravel loss over a period of time due to passage of vehicles and inaccessibility during rains. The best solution to reduce these problems is to seal the gravel roads instead of maintaining it, since many studies showed that the maintenance of unsealed road is more costly than the sealed road over a period of time. Hence, a project has been taken up to give full and all weather connectivity using locally available materials. Up to the surface course, the selected road was constructed using the locally available gravel. Many sealing techniques are available, out of which, open graded premix surfacing (OGPS) was opted in this study. This paper aims at studying the performance evaluation of gravel surface sealed with OGPS. The variables considered in this study are: gravel surface type, primer rate, and binder type. Past researchers found that the roughness, skid resistance and texture depth significantly affect the performance of sealed gravel roads and these three parameters are considered as performance indicators in this study. Eight sets of data were collected at regular intervals starting from November 2013 to March 2015. The surface distresses were also measured. From the analysis it was observed that the roughness on emulsion based OGPS was more when compared to bitumen based OGPS. Emulsion based OGPS resulted in less texture depth when compared to bitumen based OGPS. Skid resistance varied differently with respect to the binder type, type of surface course and priming rate. Even though there is little effect of gravel surface course type on roughness and texture depth, the effect of primer rate on roughness, texture depth, and skid resistance is negligible.

Asphalt pavements vary in longevity because of the various factors that cause deterioration of the chemical and physician association of the binder to the aggregate. As soon as the freshly laid hot asphalt pavement mix begins to cool, so also begins the aging process which will eventually initiate and enhance the deterioration of the asphalt. When oxygen and water, which constantly bathe the pavement, start to combine with the asphaltic binder of the pavement, a chemical change takes place. At first, this process is necessary for the pavement to become hard and firm. Later, if this process is not arrested, a complete deterioration of the asphaltic binder will take place and reduce the pavement to a layer of loose stone. The asphalt binder is essentially what differentiates a gravel road from a paved road. It is the purpose of this chapter to present the chemistry of asphalt and the chemistry of the asphalt–aggregate bond.