Pavement Evaluation and Rehabilitation Design Methodology Currently Used on Low-Volume Roads in Southern Africa

2003 ◽  
Vol 1819 (1) ◽  
pp. 343-352 ◽  
Author(s):  
J. A. Grobler ◽  
A. Taute ◽  
I. Joubert
Keyword(s):  
Southern Africa ◽  
Design Methodology ◽  
Low Cost ◽  
Cost Effective ◽  
Past Performance ◽  
The Road ◽  
Low Volume Roads ◽  
Pavement Evaluation ◽  
Wide Range ◽  
Low Volume

A pavement evaluation and rehabilitation design methodology is currently employed in southern Africa on relatively light pavement structures used for low-volume roads. The pavements normally consist of natural gravel materials in most layers and thin bituminous surfacings. When nearing the end of their design lives, they exhibit distresses ranging from minor deformation through aging of the surface to structural cracking and potholes. Rehabilitation options normally involve light stone seals or other inexpensive and cost-effective treatments. The phases of investigation for pavement evaluation and rehabilitation designs start with desk study to establish the history of the road and its past performance from pavement management system outputs. Detailed visual evaluations are then conducted of road features and extent of various forms of distress. These data are presented followed by a decision-making process to select areas for more detailed testing. All the information is used to determine the causes of distress and likely rehabilitation alternatives. Further destructive and nondestructive testing is carried out to predict performance of rehabilitation designs and equivalent annual cost comparisons. Rehabilitation design is also done with use of the dynamic cone penetrometer. Decision criteria are set for use of tests undertaken in the assessments, and test results are evaluated. This procedure normally results in a wide range of rehabilitation options, from application of a diluted emulsion as a surface rejuvenator to more extensive patching and resealing to major rehabilitation and overlays. This process effectively produces cost-effective solutions that maximize limited budgets. It is essential that the road authority be prepared to share the risks of the low-cost options with the designer. In this way benefits of low-cost solutions are realized, whereas, in a limited number of instances, premature distress may have to be repaired under routine maintenance.

Otta Seals and Gravseals as Low-Cost Surfacing Alternatives for Low-Volume Roads: Experiences in South Africa

2003 ◽  
Vol 1819 (1) ◽  
pp. 338-342 ◽  
Author(s):  
Simon Oloo ◽  
Rob Lindsay ◽  
Sam Mothilal
Keyword(s):  
South Africa ◽  
Low Cost ◽  
Cost Savings ◽  
Cost Effective ◽  
Field Trials ◽  
Low Volume Roads ◽  
Kwazulu Natal ◽  
Traffic Volumes ◽  
Low Volume ◽  
To Come

The geology of the northeastern part of the province of KwaZulu–Natal, South Africa, is predominantly alluvial with vast deposits of sands. Suitable gravel sources are hard to come by, which results in high graveling and regraveling costs brought about by long haul distances and accelerated gravel loss. Most gravel roads carry fewer than 500 vehicles per day of which less than 10% are heavy vehicles. The high cost of regraveling has led to consideration of upgrading such roads to surfaced standard, even though traffic volumes do not justify upgrading. Traditional chip seals are expensive and cannot be economically justified on roads that carry fewer than 500 vehicles per day. The KwaZulu–Natal Department of Transport is actively involved in efforts to identify cost-effective alternative surfacing products for low-volume roads. Field trials were conducted with Otta seals and Gravseals, which have been used successfully in other countries, as low-cost surfacing products for low-volume roads. The Otta seal is formed by placing graded aggregates on a relatively thick film of soft binder that, because of traffic and rolling, works its way through the aggregates. Gravseal consists of a special semipriming rubberized binder that is covered by a graded aggregate. Both Otta seals and Gravseals provide relatively flexible bituminous surfaces suitable for low-volume roads. Cost savings are derived mainly from the broad aggregate specifications, which allow for the use of marginal materials.

scholarly journals A Novel Adaptive Pixels Segmentation Algorithm for Pavement Crack Detection

2021 ◽  
Author(s):  
Nima Safaei ◽  
Omar Smadi ◽  
Babak Safaei ◽  
Arezoo Masoud
Keyword(s):  
Crack Detection ◽  
Low Cost ◽  
Local Level ◽  
Cost Effective ◽  
Segmentation Algorithm ◽  
Pavement Maintenance ◽  
Detection Systems ◽  
Wide Range ◽  
Cost Efficient ◽  
Pavement Crack Detection

<p>Cracks considerably reduce the life span of pavement surfaces. Currently, there is a need for the development of robust automated distress evaluation systems that comprise a low-cost crack detection method for performing fast and cost-effective roadway health monitoring practices. Most of the current methods are costly and have labor-intensive learning processes, so they are not suitable for small local-level projects with limited resources or are only usable for specific pavement types.</p> <p>This paper proposes a new method that uses an improved version of the weighted neighborhood pixels segmentation algorithm to detect cracks in 2-D pavement images. This method uses the Gaussian cumulative density function as the adaptive threshold to overcome the drawback of fixed thresholds in noisy environments. The proposed algorithm was tested on 300 images containing a wide range of noise representative of different noise conditions. This method proved to be time and cost-efficient as it took less than 3.15 seconds per 320 × 480 pixels image for a Xeon (R) 3.70 GHz CPU processor to determine the detection results. This makes the model a perfect choice for county-level pavement maintenance projects requiring cost-effective pavement crack detection systems. The validation results were promising for the detection of low to severe-level cracks (Accuracy = 97.3%, Precision = 79.21%, Recall= 89.18% and F<sub>1</sub> score = 83.9%).</p>

Evaluation of the Long-Term Performance of Woven Geotextile Used between Base Course and Subgrade of a Paved Road

2019 ◽  
Vol 2673 (8) ◽  
pp. 310-321 ◽  
Author(s):  
Saad Ullah ◽  
Burak F. Tanyu ◽  
Erol F. Guler ◽  
Edward J. Hoppe ◽  
Emre Akmaz
Keyword(s):  
Transportation Network ◽  
Experimental Program ◽  
The Road ◽  
Low Volume Roads ◽  
Road Profile ◽  
Low Volume ◽  
Base Course ◽  
Virginia Department ◽  
Paved Road ◽  
Term Performance

The purpose of this research was to investigate the properties of the exhumed geotextile from a low-volume road on the Virginia Department of Transportation network. The exhumed geotextiles have been in service for 23 years, which provided an opportunity to evaluate the longevity of the materials as well as to make assessments of how it relates to the changes in material properties. During this investigation, subgrade and base course materials were also obtained from the same site and an experimental program was developed to evaluate the effectiveness of the exhumed geotextiles for separation, stabilization, and filtration for the base course thicknesses of 4, 6, and 8 in. The results from this study combined with the results from the previous studies conducted at the same site showed that when the geotextile is placed between the subgrade and base course, the thinner the pavement section, the more evident the effectiveness of the geotextile improvements. One important finding of this research was that the placement of a geotextile reduced the particle breakage caused by abrasion under the applied transient loads. This was observed as a stabilization effect of the geotextile inclusion. As a general conclusion, for low-volume roads with relatively thin pavement sections, properly selected geotextiles provide benefits for separating the subgrade and base course (minimizing pumping), filtering infiltrated or ground water, and stabilizing the road profile. These benefits become more apparent when the thickness of the base course is less than 8 in.

scholarly journals A Buckling Flexure-Based Force-Limiting Mechanism

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Jonathan Slocum ◽  
Kenneth Kamrin ◽  
Alexander Slocum
Keyword(s):  
Finite Element ◽  
Design Methodology ◽  
Structural Model ◽  
Cost Effective ◽  
Element Model ◽  
Single Shot ◽  
Excessive Force ◽  
Molding Machine ◽  
Preliminary Model ◽  
Wide Range

A force-limiting buckling flexure has been created which can be used in a wide range of applications where excessive force from an implement can cause harm or damage. The buckling flexure is monolithic, contains no electronics, and can be manufactured using a single shot in an injection molding machine, making it cost effective. In this paper, the design of the flexure is applied to a force-limiting toothbrush as a design study to show its application in a real-world technology. An overview of the buckling flexure is presented, and a structural model is presented to predict when the flexure will elastically buckle. Flexures of different geometries were tested and buckled. The data show that the model can predict buckling of the flexure with an error of 20.84%. A finite element model was also performed which predicts buckling of the flexure within an error of 25.35%. Furthermore, a preliminary model is presented which enables the design of the buckling beam’s displacement, such that the total breakaway deformation can be maximized, making sensing the sudden deformation easier to detect. As part of the application of the buckling flexure, an ergonomic, injection moldable toothbrush was created with the flexure built into the neck of the brush. When the user applies too much force while brushing, the flexure gives way and alerts the user when they have applied too much force; when the user lets off the force, the brush snaps back to its original shape. This design methodology is generalized and can be utilized in other force limited applications where an injection-moldable, pre-set force, and purely mechanical breakaway device is desired.

Improving Unpaved Roads in Virginia: Case Study

2003 ◽  
Vol 1819 (1) ◽  
pp. 149-154
Author(s):  
Michael W. Dunn ◽  
S. Noelle On
Keyword(s):  
Cost Effective ◽  
Weather Conditions ◽  
Small Scale ◽  
Elected Officials ◽  
Unpaved Roads ◽  
The Road ◽  
Improvement Process ◽  
Key Factor ◽  
Low Volume ◽  
Virginia Department

Minimizing costs and streamlining the construction of low-volume roads offers an opportunity for transportation agencies to effectively meet the needs of rural citizens. The Virginia Department of Transportation (VDOT) maintains approximately 56,941 mi of the state’s roads, including Interstate, primary, and secondary facilities. Between 1987 and 1994, VDOT paved nearly 1,900 mi of unpaved roads. In rural parts of the state, many miles of state-maintained roads still have gravel and dirt surfaces. Each year the local transportation residency offices, in conjunction with local elected officials, contractors, and area citizens, strive to improve and pave as many miles of gravel and dirt roads as possible. The Hillsville Residency of VDOT, located in rural Carroll and Floyd Counties, has developed an efficient and cost-effective method for improving low-volume gravel and dirt roads. This process relies heavily on cooperative efforts by VDOT, contractors, elected officials, and especially citizens. Land donations from citizens represent the cornerstone of this process, signifying that citizen cooperation is the key factor in a project’s success. Because most of the decisions in the improvement process are at the local residency level, trusting relationships and frequent communication can be established, small-scale and local contractors are given more business opportunities, and local VDOT personnel can better understand citizen concerns and perform road improvements accordingly. In addition, the time line for the road improvement process is based on seasons—the most appropriate weather conditions are considered for the work being performed. This program enables more roads to be paved each year, improving the level of service and quality of life for local citizens.

LZER0: GNSS cost-effective real-time positioning applied to landslide monitoring

2020 ◽  
Author(s):  
Lavinia Tunini ◽  
David Zuliani ◽  
Paolo Fabris ◽  
Marco Severin
Keyword(s):  
Real Time ◽  
Monitoring System ◽  
Low Cost ◽  
Cost Effective ◽  
Single Frequency ◽  
Landslide Monitoring ◽  
Natural Risk ◽  
Near Surface ◽  
Landslide Event ◽  
Wide Range

&lt;p&gt;The Global Navigation Satellite Systems (GNSS) provide a globally extended dataset of primordial importance for a wide range of applications, such as crustal deformation, topographic measurements, or near surface processes studies. However, the high costs of GNSS receivers and the supporting software can represent a strong limitation for the applicability to landslide monitoring. Low-cost tools and techniques are strongly required to face the plausible risk of losing the equipment during a landslide event.&lt;/p&gt;&lt;p&gt;Centro di Ricerche Sismologiche (CRS) of Istituto Nazionale di Oceanografia e di Geofisica Sperimentale OGS in collaboration with SoluTOP, in the last years, has developed a cost-effective GNSS device, called LZER0, both for post-processing and real-time applications. The aim is to satisfy the needs of both scientific and professional communities which require low-cost equipment to increase and improve the measurements on structures at risk, such as landslides or buildings, without losing precision.&lt;/p&gt;&lt;p&gt;The landslide monitoring system implements single-frequency GNSS devices and open source software packages for GNSS positioning, dialoguing through Linux shell scripts. Furthermore a front-end web page has been developed to show real-time tracks. The system allows measuring real-time surface displacements with a centimetre precision and with a cost ten times minor than a standard RTK GPS operational system.&lt;/p&gt;&lt;p&gt;This monitoring system has been tested and now applied to two landslides in NE- Italy: one near Tolmezzo municipality and one near Brugnera village. Part of the device development has been included inside the project CLARA 'CLoud plAtform and smart underground imaging for natural Risk Assessment' funded by the Italian Ministry of Education, University and Research (MIUR).&lt;/p&gt;

Nature and Effects of Low-Volume Roads in Botswana

2003 ◽  
Vol 1819 (1) ◽  
pp. 88-95 ◽  
Author(s):  
Bizzar B. Madzikigwa
Keyword(s):  
Rural Areas ◽  
Road Network ◽  
Good Condition ◽  
Construction Materials ◽  
Road Construction ◽  
Rapid Improvement ◽  
The Road ◽  
Low Volume Roads ◽  
Low Volume ◽  
Sand And Gravel

The road sector in Botswana continues to develop its road network throughout the country at a tremendous rate. When Botswana gained independence in 1966, it had only 10 km (16 mi) of bitumen road. By 1992 the total length of bituminous surfaced road reached 3500 km (2,175 mi) out of a total road network of 18 000 km (11,285 mi). These statistics clearly show that the majority of roads are not yet surfaced; these are low-volume roads that provide access to the rural areas where most of the country’s population is found, though in low density. In spite of the rapid improvement in the quality of the national road network in recent years, much remains to be done. In the early 1970s and early 1980s the rural roads unit was introduced in the Ministry of Works Transport and Communications, which was charged with the responsibility of design and construction of low-volume roads around the country in a bid to integrate the country’s road network. This unit was later disbanded in the 1990s, and all roads are improved through the conventional procurement system using private contractors. For these roads the justification of a surfacing project based on conventional economic return methods does not apply, and worse still, the road improvements have to compete with other amenities for the same limited resources. Three ministries in Botswana are responsible for roads: Ministry of Works Transport and Communications, Ministry of Local Government, and Ministry of Trade, Industry, Wildlife and Tourism. These ministries have different responsibilities for different roads within the country, and earth, sand, and gravel roads are found under the jurisdiction of each of the ministries. The major drawbacks concerning low-volume roads in Botswana are inadequate maintenance, poor road construction materials, and the environmental impacts of the roads. Since the budget and resources are inadequate to keep these roads in good condition, it would be prudent to find technological means that would improve the locally available road construction materials so as to minimize their effects on the environment and vehicle operating costs.

Strength and Behavior of Materials for Low-Volume Roads as Affected by Moisture and Density

2003 ◽  
Vol 1819 (1) ◽  
pp. 104-109 ◽  
Author(s):  
P. Paige-Green
Keyword(s):  
Quality Assurance ◽  
Southern Africa ◽  
Laboratory Testing ◽  
Simple Technique ◽  
Material Strength ◽  
Pavement Materials ◽  
Moisture Contents ◽  
Low Volume Roads ◽  
Low Volume ◽  
And Behavior

The relationships among strength, moisture, and density in pavement subgrades and layerworks are well known, but they have particular significance in low-volume roads. In these roads, the specified density is frequently not achieved (quality assurance testing tends to be reduced), and moisture fluctuations are more severe with greater consequences. Traditional studies of the material strength for these roads in southern Africa are based almost entirely on the California bearing ratio (CBR), a test with inherent problems. The test is routinely carried out to identify whether the materials under consideration have the required soaked strengths (typically CBRs of 80% or 45% for bases of different standards) at the design compaction density. Studies of the CBR at different moisture contents and densities should be carried out to identify the implications of variations in these properties on the behavior of pavement materials. A simple technique to be carried out during conventional laboratory testing was developed. Aspects pertaining to this type of study were evaluated, and the findings were related to low-volume road behavior.

Laboratory and Field Test Study on Fly Ash as Subgrade Filling

2010 ◽  
Vol 146-147 ◽  
pp. 859-864
Author(s):  
Huan Ling Wang ◽  
Miao He
Keyword(s):  
Fly Ash ◽  
Field Test ◽  
Low Cost ◽  
Construction Technology ◽  
Construction Process ◽  
The Road ◽  
Test Study ◽  
Wide Range ◽  
Road Performance ◽  
Gravel Pile

Fly ash has become increasingly wide range of applications in expressway as a new environment friendlymaterial, its range of applications are fromthe CFG( Cement Fly-ash Gravel) pile of soft ground、pavement admixture to embankment materials et al. Fly ash used in expressway has many advantages, such as, it can save farmland, has a small settlement after construction and low cost as a light embankment filling. In this paper, based on an expressway in Jiangsu province, the fly ash used as a subgrade filling, a series of fly ash laboratory and field test have been conducted. The construction technology, important construction parameters, construction process control and compaction quality assessment on fly ash have been analyzed on the basis of the tests result, the road performance and construction control key methods of fly ash obtained, which can guide scientific construction.

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