Low-volume Roads Research Articles

Mechanistic Basis for Permit Fee Decision of Superloads Traveling on Low-Volume Roads Using Structural Damage Evaluation

Superloads, including “Implements of Husbandry” and “Superheavy Loads” transporting significant amounts of heavy agricultural and industrial products, frequently travel on county or municipal roads designed for low-volume traffic to avoid interrupting highway traffic flow by their slow-moving behavior and wide vehicle widths. The non-standardized loading configurations and high gross vehicle and axle weights of superloads have significant potential for causing unexpectedly greater distress on low-volume roads than the general vehicle classes categorized for U.S. roads by the Federal Highway Administration. To evaluate the impact of superloads on paved and granular roads designed for low-volume traffic, a mechanistic road structural and damage-associated cost analysis is needed for predicting unexpected damage induced by various types of superloads, and to provide a logical basis for superload permit fee decisions. In this study, a layered elastic theory-based road and pavement analysis was performed to quantify damage to flexible pavements and granular roads caused by superloads. Costs associated with damage to flexible pavements and granular roads subjected to a single pass of various superload types were also derived and compared through multivariate life cycle cost analysis. The potential permit fees for each type of superload traveling under different road conditions were then suggested by calculating damage-associated costs related to traffic, road structure, material, and treatment types.

Subgrade resilient modulus variation in low-volume roads design in north-eastern Brazil

The current asphalt pavement design method instituted in Brazil, MeDiNa, requires tests to determine the parameters of resilient modulus and permanent deformation of the granular layers. As these tests have a long execution time and high cost, this study analysed the variation of the resilient modulus (using composite model tested and linear predicted values) of low-volume road subgrade and the impact on the pavement design. This study simulated four different subgrades considering the soils of the metropolitan region of Fortaleza, Ceara, north-eastern Brazil and three predefined pavement structures. Total and subgrade rutting provided by the MeDiNa software were used as evaluation parameters. The simulation results allowed the authors to verify that the calculated rutting values are very close despite the resilient modulus adopted. In conclusion, road designers can consider any predicted linear value of the resilient modulus or composite models in the design of these highways, even with forecast errors greater than 20%. The study also proposes a low-volume road design catalogue considering the subgrades analysed.

Development of a Bridge Railing Optimized for Rural, Low-Volume Roads

A new steel bridge rail was developed for use on rural, low-volume bridges. The railing consisted of 31-in. tall, 12-gauge W-beam guardrail mounted on S3x5.7 posts, which were supported by steel square-tube sockets. These side-mounted sockets were attached to the deck edge using a unique bolted design that connects directly to coupling nuts and threaded anchor rods embedded into the bridge deck. Thus, during a crash, the tensile impact loads are transferred directly to the anchor rods and the risk of damage to the deck edge is minimized. Full-scale crash testing was conducted according to test 2 to 11 of the AASHTO’s Manual for Assessing Safety Hardware (MASH). The test vehicle struck the bridge rail at 44.2 mph and an angle of 25.5° and was successfully contained and redirected. Damage to the bridge rail consisted of bent posts and deformed guardrail. No damage to the deck or sockets was observed. The tests passed all evaluation criteria of MASH test 2 to 11. The new railing was deemed crashworthy to MASH Test Level 2 (TL-2) with a post spacing of 75 in. Additionally, when the post spacing is reduced to 37.5 in., the railing was determined to be MASH Test Level 3 (TL-3) crashworthy through a comparison to similar, crash-tested, W-beam guardrail systems. BARRIER VII simulations showed that the new railing could be directly connected to the Midwest Guardrail System without a transition. Guidance was provided pertaining to the length of guardrail required adjacent to the bridge rail.

Innovative Air Convection Embankment for Cold/Arctic Region Low-Volume Roads

Roadbed thaw settlement is a unique challenge for the durability of low-volume roads (LVRs) in permafrost regions. Air convection embankment (ACE) is an effective technique that acts as a semi-heat-transfer system to control temperature variation and reduce the thaw depth of subsoil. However, limited by the shortage of the necessary crushed rocks within a short distance, building an ACE in Alaska, U.S., is prohibitively expensive. Previous studies identified the feasibility of using cellular concrete for ACE and determined the optimized thickness of the cellular concrete aggregate interlayer for ACE. However, the economic efficiency and thermal and mechanical performance of the optimized, innovative cellular concrete aggregate ACE need further investigation. Therefore, two innovative cellular concrete ACEs with reasonable heights for cold/Arctic region LVRs were evaluated in this study. A thermal-mechanical coupling model was created using ANSYS Fluent and ANSYS Mechanical to evaluate the thermal and mechanical stability of the two optimized innovative cellular concrete aggregate ACEs by comparing them with a typical Alaskan flexible pavement, a silty sand/gravel embankment, and a conventional crushed-rock ACE. The fatigue damage was predicted using the elastic-based Alaska Flexible Pavement Design (AKFPD) program. A life-cycle cost analysis was conducted using AKFPD to evaluate the overall long-term economic efficiency of the cellular concrete ACEs. The results showed that cellular concrete ACE could achieve better thermal and mechanical performance with much lower embankment height than crushed-rock ACE. The cost analysis showed that the proposed cellular concrete ACEs had a significant cost advantage over the conventional crushed-rock ACE.

Sustainable Binary Blending for Low-Volume Roads—Reliability-Based Design Approach and Carbon Footprint Analysis

The utilization of industrial by-products as stabilizers is gaining attention from the sustainability perspective. Along these lines, granite sand (GS) and calcium lignosulfonate (CLS) are used as alternatives to traditional stabilizers for cohesive soil (clay). The unsoaked California Bearing Ratio (CBR) was taken as a performance indicator (as a subgrade material for low-volume roads). A series of tests were performed by varying the dosages of GS (30%, 40%, and 50%) and CLS (0.5%, 1%, 1.5%, and 2%) for different curing periods (0, 7, and 28 days). This study revealed that the optimal dosages of granite sand (GS) are 35%, 34%, 33%, and 32% for dosages of calcium lignosulfonate (CLS) of 0.5%, 1.0%, 1.5%, and 2.0%, respectively. These values are needed to maintain a reliability index greater than or equal to 3.0 when the coefficient of variation (COV) of the minimum specified value of the CBR is 20% for a 28-day curing period. The proposed RBDO (reliability-based design optimization) presents an optimal design methodology for designing low-volume roads when GS and CLS are blended for clay soils. The optimal mix, i.e., 70% clay blended with 30% GS and 0.5% CLS (exhibiting the highest CBR value) is considered an appropriate dosage for the pavement subgrade material. Carbon footprint analysis (CFA) was performed on a typical pavement section according to Indian Road Congress recommendations. It is observed that the use of GS and CLS as stabilizers of clay reduces the carbon energy by 97.52% and 98.53% over the traditional stabilizers lime and cement at 6% and 4% dosages, respectively.

Strength evaluation of cementitious grout macadam as a concrete pavement material for low-volume roads in India: a preliminary study

Strength evaluation of cementitious grout macadam as a concrete pavement material for low-volume roads in India: a preliminary study

An Assessment of Strength, Durability and Economic Benefits of Stabilized Silty Soil for Construction of Low Volume Roads

An Assessment of Strength, Durability and Economic Benefits of Stabilized Silty Soil for Construction of Low Volume Roads

Three-Year Field Performance of a Low Volume Road With 100% Reclaimed Asphalt Pavement Cold Mix With Rejuvenator

In the pavement construction industry, 100% reclaimed asphalt pavement (RAP) has not been widely adopted, although it is a sustainable technique that can significantly contribute to the ambitious goal of carbon neutralization. The field performance of this technology is rarely well documented, resulting in a lack of confidence in using it. To address the gap, this paper presents three-year field performance monitoring of a low volume road that used 100% RAP cold mix with a rejuvenator. A three-round distress survey was conducted for 7, 22, and 34 months of service, and the effects of staged construction and edge compaction on the road conditions were evaluated to determine the best practice in paving with 100% RAP with rejuvenator. The change of pavement condition index with time was constructed to better understand the performance evolution of a low volume road in a warm and non-freeze climate zone. Based on the three-year field performance data, it was found that the major distresses were weathering and raveling and neither cracking nor rutting was observed. This study recommends enhancing compaction efforts during the construction stage to achieve a better in-place density and completion of mixing and compaction on the same day for better durability and field performance. As a low-cost solution, the application of 100% RAP with rejuvenator is feasible for a low volume road that is located in a wet and non-freeze climate zone.

Enhancing the Performance of Roller-Compacted Concrete Pavement by Synergetic Improvement of Packing Density, Lubrication, and Moisture State of Recycled Concrete Aggregate

Roller-compacted concrete pavement (RCCP) is considered superior to other pavement types with reference to cost, ease of construction, and performance. However, the aggregate demand is significantly higher in RCCP than in the conventional concrete pavement. It is predicted that natural minable limestone sources would be exhausted in India in the next 30 to 40 years. One way to reduce the natural aggregates (NA) requirements in RCCP is through the integration of recycled concrete aggregates (RCA). However, the physical property of RCA is significantly inferior to that of NA owing to the presence of adhered mortar (AM), which increases the water demand by 2.3 to 4.6 times and affects the compactness and hardened-state behavior of RCCP. This study has tried to enhance the compactness and improve the performance of RCCP containing RCA (coarse, fine, and total RCAs) through different synergetic approaches. This, in turn, enhances the interlocking capacity using the particle packing approach, followed by mitigating the negative effects of AM by altering the moisture states, then improving the compactability and lubricating the matrix with superplasticizers. The results depict that altering the moisture states alone could adversely affect the RCCP performance because of the moisture transfer mechanism from the hydraulic gradient. Moreover, the inclusion of superplasticizers in different moisture states could manifest better aggregate rearrangement and compactability. Further, it could improve the tensile behavior of the RCCP compared with the concrete containing NA. These findings favor the complete replacement of NA by RCA for low-volume rural road construction.

Survival Analysis of Concrete Overlays on Low-Volume Roads in Iowa

Concrete overlays are an important component of Iowa’s rural road network. More than 2,000 centerline miles of concrete overlays have been paved in Iowa over the last few decades, including many overlays on low-volume roads serving 400 vehicles per day or less. In this study, a survival analysis was performed using automated pavement condition data collected on Iowa’s concrete overlays to obtain a probabilistic assessment of concrete overlay service life, paying particular attention to the performance of overlays on low-volume roads. Concrete overlays were found to perform very well, with a 30-year survival probability of 85.3% for all projects to rehabilitation or reconstruction, and 76.6% for overlays only on low-volume roads. Survival life was reduced when the survival condition was changed to performance thresholds based on a pavement condition index (PCI) of 60/100 and an International Roughness Index (IRI) value of 170 in./mi, but was still good overall. Overlays tended to reach the failure condition for PCI before IRI, indicating that cracking is a more common distress than surface roughness. Another important finding was that concrete on asphalt overlays had a longer median survival life and a greater 30-year survival probability than concrete on concrete-unbonded overlays. Overall, concrete overlays have performed well in Iowa and are well suited to low-volume roads and rural county highways.

Revisiting Field Performance of Cold Central-Plant Recycled Test Sections at MnROAD Low-Volume Road

In 2017 four test sections (test sections 133, 233, 135, and 235) containing a cold central-plant recycled (CCPR) layer underneath a surface treatment were constructed on the MnROAD low-volume road (LVR). Two types of CCPR mix designs were constructed: test sections 133 and 235 contained an emulsified asphalt; test sections 135 and 233 contained a foamed asphalt. Each CCPR mix design (foamed asphalt and emulsified asphalt) had two types of wearing surface layers (double chip seal and 1.5 in. HMA [hot-mix asphalt] overlay—thinlay) to create the four test sections. The rest of the pavement structure beneath the newly constructed CCPR was left in place and consistent throughout all four test sections with the remaining granular base over the existing clay subgrade. This paper presents a revisiting of the field performance of the CCPR test sections at the MnROAD LVR. To do this extensive field data was collected over approximately 3 years through visual distress surveys, and ride quality, rutting, and falling-weight deflectometer testing. Field study determined that both CCPR mix designs (foam and emulsion) performed similarly and the thinlay HMA layer outperformed the double chip seal in respect of rutting; but both surfaces are considered valid alternatives for future applications depending on the traffic volumes expected.

Sign Life Expectancy on Low-Volume Roads in Iowa

Traffic signs provide warning and guidance information to drivers 24 h a day. They also represent a significant maintenance and replacement concern and cost for agencies with the advent of retroreflectivity requirements. In some cases, agencies choose to replace their signs in conjunction with the end of the manufacturer warranty period or other time intervals to maintain sign retroreflectivity. However, this could result in signs being replaced while they still exceed their minimum retroreflectivity requirements, with labor and material costs being incurred years before necessary. This research evaluated retroreflectivity data from in-service signs in Iowa, U.S., to determine expected sign life values. It evaluated 10,799 retroreflectivity data points across three different sheeting materials for a variety of sign types. A total of 65 linear regression models were developed to evaluate signs by sheeting type, age, and sign category (regulatory, warning, and guide), as well as directional orientation. The results indicated that all sheeting materials, sign types, and sign directions were predicted to have lives of at least 10 years before falling below Manual on Uniform Traffic Control Devices (MUTCD) minimums. Plots of retroreflectivity versus age indicated that many signs remained well above the MUTCD minimums at the predicted age where failure was expected. In general, the predicted lives for a material/sign type/direction combination were greater than 5 years longer than manufacturer warranty periods. For conservative purposes, agencies could consider a sign to be approaching minimum retroreflectivity levels at approximately 5 years past the manufacturer warranty, based on the research results.

Exploring Crowdsourced Hard—Acceleration and Braking Event Data for Evaluating Safety Performance of Low-Volume Rural Highways in Iowa

There are over four million miles of two-lane roadways across the United States, of which a substantial portion is low-volume roads (LVR). Traditionally, most traffic safety efforts and countermeasures focus on high-volume high-crash urban locations. This is because LVRs cover an extensive area, and the rarity of crashes makes it challenging to use crash data to monitor the safety performance of LVRs regularly. In addition, obtaining up-to-date roadway information, such as pavement or shoulder conditions of an extensive LVR network, can be exceptionally difficult. In recent times, crowdsourced hard-acceleration and braking event data have become commercially available, which can provide precise geolocation information and can be readily acquired from different vendors. The present paper examines the potential use of this data to identify opportunities to monitor the safety of LVRs. This research examined approximately 12 million hard-acceleration and hard-braking events over a 3-months period and 26,743 crashes, including 9373 fatal injuries over the past 5-year period. The study found a moderate correlation between hard acceleration/hard-braking events with historical crash events. This study conducted a hot spot analysis using hard-acceleration/hard-braking and crash datasets. Hotspot analysis detected spatial clusters of high-risk crash locations and detected 848 common high-risk sites. Finally, this paper proposes a combined ranking scheme that simultaneously considers historical crash events and hard-acceleration/hard-braking events. The research concludes by suggesting that agencies can potentially use the hard-acceleration and hard-braking event dataset along with the historical crash dataset to effectively supervise the safety performance of the vast network of LVRs more frequently.

Integrating a Multi-criteria Route Optimization with ArcGIS for Gravel Road Data Collection

The ability to identify and collect low-volume roads’ data, especially gravel roads, is critical in transportation planning. Developing an effective method for gravel-road data collection allows both decision-makers and local agencies to efficiently obtain information regarding road conditions. In this study, a geographical information system (GIS)-based decision- support system was applied to assist local agencies in determining reliable access routes to all gravel roads in Wyoming. The routing criteria were developed using the Network Analyst tool of ArcGIS software based on the restrictions on average daily traffic (ADT) volume values, speed limits, driving distances and driving hours per day. Results indicated that the routing maps created by ArcGIS software were an easy-to-use method to plan and schedule data collection on gravel roads. The routing analysis provided a reliable means to minimize driving time and distance. The methodology developed in this study may be employed by local transportation agencies for road-maintenance purposes in rural areas. KEYWORDS: Low-volume roads, Gravel roads, Route optimization, ArcGIS, Data collection.

Geotechnical investigations on Alccofine stabilized kaolin clay

Clay soil having high kaolinite content are strenuous to work with as it has low compressive strength and bearing capacity. They tend to cause failures in supporting structures and pavements overlying them. Chemical stabilization is a viable option to improve the strength of the clay. A new soil stabilizer made from processed GGBS, Alccofine 1109SS , is used for stabilization. Alccofine is being used as a micro filler for concrete. The same has been used in 3,6,9, and 12 % to prepare specimens, and these specimens were tested after controlled curing of 0,7,14 and 28 days. The geotechnical strengths of these specimens were tested for Unconfined compressive strength (UCS) and split tensile strength (STS). Mixing 12% of Alccofine led to an improvement of around 500 % in UCS strength fa or cud of 28 days. The UCS strength for K91A9 and K88A12 exceed 1700 kPa, recommended by IS code for sub-base courses in low-volume roads, and thus can be used for it. Soaked and unsoaked CBR values were found to have increased by more than 100 % than pure kaolin clay. Further, the morphological test results of SEM and XRD are discussed. The optimum recommended percentage of Alccofine to be used as a stabilizing agent considering economy and sustainability is 9 %.

A Novel Network Screening Methodology for Rural Low-Volume Roads

A Novel Network Screening Methodology for Rural Low-Volume Roads

Coordinated Use of Digital Construction Tools for Renewal Design of Low-Volume Roads: A Norwegian Case Study

Coordinated Use of Digital Construction Tools for Renewal Design of Low-Volume Roads: A Norwegian Case Study

Analysis of Durability and Strength of Cement Treated Soils for Sub-Base and Base Layers of Pavement

Abstract: Replacement of natural aggregates with moderately cement treated soil in sub-base and base layers is identified to be prevailing construction practice in low volume roads. However, robustunderstanding of strength and durability characteristics of these soil-cement moderately treatedlayers is considered to be significant prerequisite. Numerous studies were carried out on conventional strength properties of soil-cement treatment in subgrade and granular layers. Limited studies were reported on understanding the durable performance of these mix material under the influence of vehicular transient loadings, and environmental loadings

Modelling Response of Soil Stabilized Low Volume Roads by Mechanistic-Empirical Approach

Modelling Response of Soil Stabilized Low Volume Roads by Mechanistic-Empirical Approach

Evaluation of the structural response of two in-service thin flexible pavements under heavy vehicle loading during different seasons by built-in sensors

ABSTRACT Long Heavy Vehicles (LHV) are considered more efficient and environmentally friendly transportation of goods compared to conventional trucks. Thus, the maximum allowable gross vehicle weight (GVW) in Sweden was increased on part of the road network from 64 to 74 tons in 2018 by increasing the vehicles’ length and the number of axle groups per vehicle but not the axle load limits. This change in loading conditions is expected to lead to changes in the structural response and degradation rate of thin pavements on the low-volume road network. To improve our understanding of thin pavements behaviour exposed to multiple axle loadings two thin pavement structures located in the north of Sweden were instrumented with road response and climate sensors. Four measurement campaigns were carried out within one year by in-situ stress and strain measurements from the built-in sensors as LHV passes over at normal speed. The recorded response was compared with numerical calculations based on multilayer elastic theory (MLET). Values of stresses and strains showed a generally good agreement with high values of coefficient of determination R 2 during different seasons when the asphalt stiffness values were adjusted based on temperature and granular layer stiffness values based on moisture.