Unsurfaced Roads Research Articles

COMPARATIVE ANALYSIS OF EVALUATION CRITERIA FOR UNPAVED RURAL ROADS: A CASE STUDY

This study focused on the evaluation of the condition of the unpaved rural road: Sauces Norte-Imbana in the province of Loja, using two main indicators: Unsurfaced Road Condition Index (URCI) and the International Roughness Index (IRI). The IRI was measured using three different devices: MERLIN, Roughometer III, and a mobile application. The collected data were statistically analyzed to determine their distribution and the correlation between the variables. The results revealed a weak correlation between these variables, indicating that each methodology may be assessing different aspects of the road condition or due to the particular conditions of the road. The lack of a strong relationship may be related to the specific characteristics of the studied road, such as its sinuosity and the influence of environmental conditions on roughness measurements. This study underscores the importance of considering a variety of factors when evaluating the condition of unpaved roads and the need to develop and apply suitable evaluation techniques for the specific conditions of each road.

Sustainable Prioritization of Public Asphalt Paved Road Maintenance

The development of transportation infrastructure is crucial for a country's progress as it enables access to social and economic amenities and acts as a vital link between production and consumption. This is particularly significant for landlocked nations like Zambia, which heavily rely on a wide network of public highways, including both paved and unsurfaced roads. Regardless of their quality and construction, all road surfaces degrade over time due to the combined effects of traffic load and environmental factors. If not properly managed, this can lead to costly repairs and rehabilitation efforts. Government organizations face a dilemma when deciding which public roads to prioritize for maintenance. This follows that the inherent hurdle is competing needs within limited finances for infrastructure development. However, the challenge of road maintenance prioritization can be addressed by adopting a multi-criteria approach. This study aims to address the issue of sustainability and provides insights into which public roads should be given priority for maintenance. The research proposes a comprehensive set of criteria focusing on sustainability and assigns relative importance to them, with emphasis on state of deterioration, emergency function, climate resilience, environment, strategic importance, social considerations, economic factors, and political importance. It suggests that road maintenance decision-making should prioritize sustainability, resilience, and societal well-being, challenging traditional assumptions.

The Begging Strategy of Andean Dogs: An Exploratory Study.

In this study, we report a particular begging strategy by Andean dogs and by humans on the unsurfaced road between the villages of Parotani and Cahiuasi in Bolivia. The positions of the dogs and humans begging and their behavioral displays were recorded. In dogs, the distance from each other was also recorded. Begging locations, for both dogs and humans, were permuted with a score, according to the higher probability of receiving food. The highest scores were assigned to the positions where cars had to slow down and the subjects were well visible, thus meriting a score corresponding to the higher probability of receiving a treat. The occurrences of the correct positioning at the external and internal parts of the bend were compared by a chi-square test. On a range of 93.3 km, the dogs were observed to always lie down at the border of the road, mainly alone (96.3%) and on hairpin bends, present due to the steep slope, obliging the vehicles to slow down. Humans were observed mainly in groups. The percentage of dogs lying on the external part of the bends was 81.2%, which was above the level of chance (p < 0.01). Humans were observed at external bends in 63.6% of cases, which was at chance level. Begging locations, for both dogs and humans, were permuted with a score according to the higher probability of receiving food. The mean scores were 1.48 and 0.65 for dogs and humans, respectively, and the difference was highly significant (p < 0.001).

Estimation of the resistance to movement of a wheeled tractor train in field tests

The purpose of the studio was to determine the movement resistance of a wheeled tractor train taking into consideration the random nature of changes in external operational factors. The research was based on the example of the unit MTZ-80+2PTS-M in the Mariinsky district of the Kemerovo (Russia) in 2021. The method of control dynamometry was used to determine the probabilistic characteristics of the traction resistance of an agricultural trailer and its dependence on the load-speed mode. The studies were carried out on various backgrounds (unsurfaced road, grain stubble and sowing field) with a trailer load from minimum to maximum. Authors have studied the energy assessment of a tractor transport unit in relation to specific natural-production conditions of its operation. Based on the results authors have revealed the influence of high-speed and load operating modes of a tractor train and determined the operating weight rational values.

Evaluation of Hexagonal Multi-Shape, Multi-Axial Geogrids in Unsurfaced Road Applications

A full-scale unsurfaced test section was constructed to evaluate the performance of two recently developed innovative geogrids, referred to as NX-1 and NX-2, having a unique combination of hexagonal, trapezoidal, and triangular aperture shapes, rib aspect ratios greater than 1.0, and a coextruded, composite polymer sheet designed to improve aggregate and geogrid interaction. The test section consisted of a 25-cm-thick crushed aggregate surface layer placed over a weak clay subgrade. Simulated truck traffic was applied using a load cart outfitted with a single-axle dual-wheel truck gear. Rutting performance and instrumentation response data gathered from earth pressure cells and single-depth deflectometers were monitored at multiple traffic intervals. It was found that the geogrids improved rutting performance when compared with an unstabilized test item, and NX-1 was found to be the best performer of the two geogrids. Calculated traffic benefit ratios ranged from approximately 1.2 at low levels of rutting up to approximately 13.0 at higher levels of rutting. Instrumentation response data indicated that the geogrids reduced measured pressure and deflection near the surface of the subgrade layer. Pressure response data in the aggregate layer suggested that the geogrids redistributed applied pressure higher in the aggregate layer, effectively changing the measured stress profile with depth.

Toward improved performance of unpaved roads: laboratory tests and field investigation of a soil-byproduct base layer

ABSTRACT In this study, the performance of two steel slag byproducts is investigated to produce mixtures for base layers of unpaved roads. The basic physical properties including Atterberg limits, grain size distribution, California bearing ratio and expansion tests of eight different mixtures of soil-byproduct are investigated in laboratory to understand the engineering properties of the mixtures. The byproducts are mixed in different proportions from 50% to 80% by weight with a local (clayey) subgrade soil. Subsequently, two selected mixtures are used to build an experimental road section along an unsurfaced road. Results demonstrate that the gradation and strength of the samples satisfy the requirements for base layers. Furthermore, the mixtures are shown to be of low-plasticity at higher byproduct content and non-expansive. Field investigations show that 12 roller passes at the standard Proctor and 14 at the intermediate Proctor are enough to reach 100% of the degree of compaction.

Evaluation of the Dynamic CBR Test on Coarse-Grained Materials

Abstract The California Bearing Ratio (CBR) test is commonly used to evaluate the quality of base courses and subbase courses, subgrades, and unsurfaced roads. It provides an empirical index value for the strength of a compacted material. However, the conventional field CBR test is time consuming. As a simple and fast alternative, a dynamic CBR test has been developed for which a falling mass is used to provide the force needed for the penetration of a piston into the tested material. The biggest advantage of the dynamic CBR test compared with the conventional CBR test is that it can be completed within very few minutes. Based on experimental data from laboratory and field tests, this article evaluates the use of the dynamic CBR test on coarse-grained materials. The laboratory program consisted of 15 materials (primary and secondary raw materials) that were compacted to different dry densities and were tested using the conventional and dynamic CBR tests. Additional field tests were performed on four of these materials. The results suggest the use of the dynamic CBR test as a valuable alternative to the static CBR test on granular materials. A general correlation formula for dynamic penetration values provided by the dynamic CBR test and conventional CBR values is presented.

Comparative Analysis of the Dynamic Cone Penetrometer-Cone Penetration Rate Design Approach against Other Methods Used for Upgrading of Low Volume Roads: Case of Uganda and Zambia

Low volume roads form a significant part of the road network in Sub-Saharan Africa (SSA). During the dry season, these often unsurfaced (predominantly gravel) roads generate a lot of dust which is a health hazard and has adverse effects on the environment. In the wet season, some sections of these roads become impassable thereby limiting accessibility and disrupting economic activities. Rapid depletion of gravel sources for road construction has rendered the re-graveling of these roads unsustainable. On the other hand, upgrading these roads to bituminous standard using conventional design approaches would be costly given the vastness of the network in question. For sustainability, it is imperative to explore alternative approaches for design of low volume sealed roads (LVSR). Research in the region has highlighted the dynamic cone penetrometer-cone penetration rate (DCP-DN) method as one such plausible approach. In the DCP-DN design approach, the DN value is used directly, without correlation with the California bearing ratio (CBR). This paper provides a comparison of the DCP-DN pavement design method with other common methods for design of LVSR in SSA—particularly Uganda and Zambia. In both countries, the DCP-DN method was found to be a promising alternative for pavement design of LVSR in relation to potential reduction in cost of implementation of the pavement layers that resulted from the design.

Long-Term Study on the Cost-Effectiveness of Dust Control and Untreated Aggregate-Surfaced Resource Roads

A long-term study of treated and untreated aggregate resource roads in Canada was conducted. The objective was to investigate the cost-effectiveness of annual dust control treatments where the hypothesis is that annual applications may prolong aggregate life. Seven sections along two road segments with different traffic levels were studied over five years. A survey of road users revealed that 88% agreed that the treated sections were safer because of the increase in visibility and quicker dust settlement times. Evaluation of surface aggregate indicated some aggregate wear but there were no significant differences between treated and untreated sections. The source and quality of crushed aggregate has an impact on road performance. The condition of the running surface did not indicate any major performance differences between the treated and untreated sections. Regardless of treatment, age, or aggregate sources, a general downward trend in Unsurfaced Road Condition Index was observed, indicating wearing course degradation over time. The study revealed a strong correlation between traffic volume and maintenance intensity. Moderately higher travel speeds were measured on the treated versus untreated sections. When the cost of treatment and maintenance was compared with historical costs, the dust control scenario was more expensive. However, when log hauling cost savings from increased travel speeds were introduced, the dust control was approximately cost neutral in low traffic scenarios and moderately better for high traffic. If non-quantifiable benefits, such as increased safety, were to be considered, application of dust control treatment is recommended.

Assessing subgrade strength using an instrumented dynamic cone penetrometer

Subgrade strength is an important aspect to be considered when designing unsurfaced roads and working platforms for pavement structures. Furthermore, dynamic cone penetration tests are used to characterize the subgrade strength. However, the results of dynamic cone penetration tests, including the penetration depth per blow, can be affected by transferred energy and the verticality of the cone penetrometer. The objective of this paper is to characterize the subgrade strength using an instrumented dynamic cone penetrometer (DCP). The instrumented DCP includes a load cell and an accelerometer, located on the cone tip, and measures the dynamic responses of force and velocity over elapsed time. Weathered soil is compacted with three different dry unit weights in a square-shaped container for lab-scale dynamic cone penetration tests. Using instrumented and standard DCPs, several dynamic cone penetration tests are performed, and the dynamic cone penetration index (DCPI) is recorded along the depth profiles. Based on the dynamic responses at the cone tip of the instrumented DCP and the principles of energy conservation, the dynamic cone resistance is suggested as a new strength index. The experimental results show that the dynamic cone resistance increases with the depth of the instrumented DCP, providing a reliable subgrade strength profile in the soil. In addition, the correlation between the DCPI obtained from the instrumented DCP and the dynamic cone resistance suggests that the dynamic cone resistance is more sensitive than the DCPI for stiff soil. Based on the correlation values of the dynamic cone resistance obtained from the instrumented DCP, the internal friction angle and California bearing ratio values can be estimated with a high degree of reliability. This study demonstrates that use of the instrumented DCP may be a promising in situ testing method for the reliable characterization of subgrade strength.

Field scene recognition for self-localization of autonomous agricultural vehicle

In this study, a field scene recognition system was developed to estimate a self-position of a traveling vehicle along a farm road by using an original capture system with three cameras, a vector quantization method to express the features of field scenes, a machine learning based scene recognition algorithm, and a vehicle position estimation algorithm with an original voting method. The potential of our system was demonstrated through five experiments performed over four months. In the experiments, the system could robustly estimate the vehicle position with the accuracy less than 1 m at the processing speed of approximately 2.0 Hz when the vehicle was driven straight along a traveling line on the targeted two types of roads: a surfaced road and an unsurfaced road, at the driving speed of 0.5 m/s. The results demonstrated an applicability of our system to navigate an autonomous agricultural robot vehicle without using GNSS.

Plot-, farm-, and watershed-scale effects of coffee cultivation in runoff and sediment production in western Puerto Rico

The combination of a topographically abrupt wet-tropical setting with the high level of soil exposure that typifies many sun-grown coffee farms represents optimal conditions for high erosion rates. Although traditionally considered as a main cause for water resource degradation, limited empirical evidence has existed to document its true contribution. This study relies on plot-scale experimental results conducted in western Puerto Rico to assess the impact of cultivated surfaces and farm access roads on runoff and sediment production from the plot to the farm and watershed scales. Results show that unsurfaced and graveled road surfaces produce one- to two-orders of magnitude more per unit area runoff than cultivated lands. Similarly, erosion rates from unsurfaced roads are about 102 g m−2 per cm of rainfall and these are two-orders of magnitude greater than from actively cultivated surfaces. Mitigation practices such as uncompacting road surfaces by ripping and gravel application reduce onsite erosion rates to 0.6% and 8% of unsurfaced conditions, respectively. At the farm scale, coffee farms are estimated to produce sediment at a rate of 12–18 Mg ha−1 yr−1, and roads are undoubtedly the dominant sediment source responsible for 59–95% of the total sediment produced. The costs associated to ameliorating erosion problems through road graveling are high. Therefore, a combined approach that treats road erosion onsite with one that traps sediment before it reaches river networks is the viable solution to this problem.

The Effect of Landscape Composition on the Abundance of Laodelphax striatellus Fallén in Fragmented Agricultural Landscapes

The spatial distribution of crop and non-crop habitats over segmented agricultural landscapes could be used as a means to reduce insect pest populations. Seven land cover categories such as wheat, rapeseed, vegetable, water, built-up, paved road, and unsurfaced road were extracted from GeoEye satellite images dating from late May to late June of 2010. Three diversity metrics and three evenness metrics were estimated from the abovementioned land cover categories for quantifying the effect of landscape composition on nymphal and adult Laodelphax striatellus Fallén. The degree of correlation between the proportion of crop cover and adjacent spatial scales (r: 0.651–0.983) was higher than the correlation between the proportion of crop cover and nonadjacent spatial scales (r: −0.255–0.896). While the degree of correlation between diversity indices and abundance of L. striatellus decreased gradually when the spatial scales varied from large (&gt;100 m radius buffer) to small (&lt;100 m). Our study suggests that when using natural biological pest control and ecological engineering practices in the rural-urban fringes, the crop field’s width should be less than 200 m and increasing vegetation diversity within such a scale will be helpful to regulate the insect pests under a certain density.

Isotopically constrained lead sources in fugitive dust from unsurfaced roads in the southeast Missouri mining district

The isotopic composition of lead (Pb) in fugitive dust suspended by a vehicle from 13 unsurfaced roads in Missouri was measured to identify the source of Pb within an established long-term mining area. A three end-member model using 207Pb/206Pb and concentration as tracers resulted in fugitive dust samples plotting in the mixing field of well characterized heterogeneous end members. End members selected for this investigation include the 207Pb/206Pb for 1) a Pb-mixture representing mine tailings, 2) aerosol Pb-impacted soils within close proximity to the Buick secondary recycling smelter, and 3) an average of soils, rock cores and drill cuttings representing the background conditions. Aqua regia total concentrations and 207Pb/206Pb of mining area dust suggest that 35.4–84.3% of the source Pb in dust is associated with the mine tailings mixture, 9.1–52.7% is associated with the smelter mixture, and 0–21.6% is associated with background materials. Isotope ratios varied minimally within the operational phases of sequential extraction suggesting that mixing of all three Pb mixtures occurs throughout. Labile forms of Pb were attributed to all three end members. The extractable carbonate phase had as much as 96.6% of the total concentration associated with mine tailings, 51.8% associated with smelter deposition, and 34.2% with background. The next most labile geochemical phase (Fe + Mn Oxides) showed similar results with as much as 85.3% associated with mine tailings, 56.8% associated with smelter deposition, and 4.2% associated with the background soil.

예산 및 도로 유지관리 : 저교통량 도로의 포장 변경을 위한 추가연구의 필요성

PURPOSES : This paper presents a description of the current issues facing road managers regarding the surface-type conversion of low-volume roads for cost savings. METHODS: The paper reviews previous works conducted toward this end, acknowledges gaps in the current research, and lays out what information is needed for further studies. RESULTS : If the cost to maintain an unsurfaced road is less than the cost of maintaining a surfaced road, then there is potential for cost savings for the management agency. However, the problem is bigger than simply maintaining the roads that already exist. If unsurfaced roads prove to be more economical than surfaced roads, then the cost to convert from a surfaced to an unsurfaced roadway, and vice versa, when necessary, must also be examined. CONCLUSIONS : No other studies have addressed the un-surfacing of a road for cost savings, and it is therefore unknown whether substantial savings can be realistically obtained by converting from a surfaced to an unsurfaced road. To determine whether a conversion policy would be a viable option, additional data and research are needed.

LAKES TOURISM DEVELOPMENT IN UTENA COUNTY

LAKES TOURISM DEVELOPMENT IN UTENA COUNTY

A Method for Assessing Costs Associated with Conversion/Reconversion of Low-Volume Roadways

This paper presents an explanation of the methods used to evaluate the costs associated with the conversion of low-volume roads to gravel and asphalt, as well as the potential reconversion to the original surface type, for the purpose of maintenance cost savings. Across the country, agencies are converting lesser-used surfaced roads into un-surfaced (gravel-type) roads in order to curtail present maintenance spending. But the conversion costs money, and there is the possibility that growth may occur that would necessitate the reconversion of the roadway, an expensive task that could negate any potential savings from the initial conversion. The conversion and maintenance costs are dependent on local material costs and road standards. The feasibility of this practice requires a more in-depth look at the costs involved with both conversion and maintenance of both surface types, as well as potential for growth in the area. This paper presents the minimum costs associated with conversion and reconversion of low-volume roads in Texas as an example of one way to assess costs for decision-making purposes.

Phase partitioning and bioaccessibility of Pb in suspended dust from unsurfaced roads in Missouri—A potential tool for determining mitigation response

Airborne particulate material collected from seventeen rural unsurfaced roads in Missouri's agricultural and resource mining areas were characterized using the BCR sequential extraction procedure and simulated in vitro body fluids to determine the phase partitioning and bioaccessibility of Pb associated with roadway dusts. Results show that dusts produced from driving over unsurfaced roads in the mining area has a substantial portion of the Pb concentration associated with the more mobile exchangeable-plus-carbonate and reducible geochemical phases. By comparison, unsurfaced road dusts outside the resource mining area have lower metal contents, as expected, and a larger portion of the total Pb concentration associated with the immobile oxidizable and non-silicate bound residual phases. SEM/EDS analysis suggests the minerals associated with the more mobile Pb components include cerussite, Pb oxides and sulfates. Compared with the coarser >1 μm size fraction of dust, the <1 μm fraction contains a substantially higher concentration of Pb in association with clay minerals. Extraction tests using simulated body fluids show that gastric fluid can mobilize as much as 69% of the total Pb concentration in mining area road dust samples after five hours. Simulated alveolar lung fluid also was an efficient extractor of Pb from the <1 μm sample dust fraction, dissolving up to 100% of the available Pb after 100 h. Regression analysis suggests that aqua regia total Pb concentration is a good predictor of mobility and bioaccessibility and can be used to minimize costs associated with monitoring suspended dust contamination.

Trace metals in fugitive dust from unsurfaced roads in the Viburnum Trend resource mining District of Missouri—Implementation of a direct-suspension sampling methodology

Fugitive dust from 18 unsurfaced roadways in Missouri were sampled using a novel cyclonic fugitive dust collector that was designed to obtain suspended bulk samples for analysis. The samples were analyzed for trace metals, Fe and Al, particle sizes, and mineralogy to characterize the similarities and differences between roadways. Thirteen roads were located in the Viburnum Trend (VT) mining district, where there has been a history of contaminant metal loading of local soils; while the remaining five roads were located southwest of the VT district in a similar rural setting, but without any mining or industrial process that might contribute to trace metal enrichment. Comparison of these two groups shows that trace metal concentration is higher for dusts collected in the VT district. Lead is the dominant trace metal found in VT district dusts representing on average 79% of the total trace metal concentration, and was found moderately to strongly enriched relative to unsurfaced roads in the non-VT area. Fugitive road dust concentrations calculated for the VT area substantially exceed the 2008 Federal ambient air standard of 0.15μgm−3 for Pb. The pattern of trace metal contamination in fugitive dust from VT district roads is similar to trace metal concentrations patterns observed for soils measured more than 40years ago indicating that Pb contamination in the region is persistent as a long-term soil contaminant.

Aggregate Physical Properties Affecting Modulus and Deformation Characteristics of Unsurfaced Pavements

AbstractThis paper presents findings from a recently completed research study at the University of Illinois aimed at investigating the effects of aggregate type and quality on mechanistic pavement response and rutting performance with implications to over 2.6 million km (1.6 million miles) of unsurfaced roads in the United States. Three aggregate types, crushed limestone, crushed dolomite, and uncrushed gravel, were tested in the laboratory for resilient modulus (MR) and permanent deformation characteristics at different factorial combinations of selected aggregate physical properties. Aggregate properties studied included particle shape and surface texture, type and amount of fines, and moisture and density in relation to required compaction conditions. Stress-dependent material characterization models determined from the laboratory MR tests were used in a nonlinear axisymmetric finite-element analysis program to compute the vertical compressive stress on top of the subgrade as a critical pavement respon...