No description available.

No description available.

Night time construction has adopted as a preferred method of scheduling to alleviate the problems caused by road works during the day. Over the past few years, night-time construction has been increased; it will inevitably continue to grow. Continued increase in the volume of roadwork done at night has resulted from a combination of road deterioration and traffic congestion. Although nighttime road construction is seen as the solution to alleviate the problems associated with day-time repairs and congestion, it has its own challenges and problems. Cost, productivity, quality, noise and human factors are some of the few factors that night-time road construction brings. This study is aimed at understanding the factors that influence the productivity of night-time construction and proposing strategies to improve productivity in the South African context. It is commonly known that quality and productivity differs from one roadwork site to another during night-time road construction. Some roadwork sites can perform well while others are worse off. However, through literature, the factors categorised as human, management and external may influence the productivity regardless of the operation. The current study investigates the influence of these factors on the productivity of work done at night through structured questionnaire. The results of the study show that there is minimal if no effect on the productivity of work done at night. Human factors that influence the performance of the labour have no impact on productivity, whereas management and external factors have minimal impact on the productivity of night-time road construction projects.

The focus of this project is highway construction zones and the impact of lane closures on traffic. By measuring throughput (the number of vehicles that can flow through a work zone in a given amount of time), analysis was performed to determine the factors that affect this value. Successful data collection uncovered a paradox. Often work zones would see no queuing, indicating the lane could have been closed for longer hours. Alternatively sites with forced flow allowed fewer vehicles through the site than expected, indicating that the design value is too high, requiring shorter lane closure hours. A generic model for throughput was developed as well as a better functioning highway specific model. In addition to these models, this project developed a spreadsheet-based form of analysis named SZUDA (Simplified work Zone User Delay Analysis) that determines queue length and approximate costs associated with road user delay.

The focus of this project is highway construction zones and the impact of lane closures on traffic. By measuring throughput (the number of vehicles that can flow through a work zone in a given amount of time), analysis was performed to determine the factors that affect this value. Successful data collection uncovered a paradox. Often work zones would see no queuing, indicating the lane could have been closed for longer hours. Alternatively sites with forced flow allowed fewer vehicles through the site than expected, indicating that the design value is too high, requiring shorter lane closure hours. A generic model for throughput was developed as well as a better functioning highway specific model. In addition to these models, this project developed a spreadsheet-based form of analysis named SZUDA (Simplified work Zone User Delay Analysis) that determines queue length and approximate costs associated with road user delay.

The City of Saskatoon is responsible for maintaining approximately 1,100 km of roads including locals, collectors, arterials, and freeways. With the aged state of the road infrastructure, increasing budget constraints limit the City’s ability to maintain existing road infrastructure to an acceptable level of service and to construct new road infrastructure. The infrastructure demands related to urban growth within the City of Saskatoon have caused a shrinking aggregate supply and increasing aggregate demand. In turn, growing demand and dwindling resources for aggregate are resulting in rapid increases to road construction costs. Aggregate sources are a non-renewable resource in Saskatchewan. Therefore, road designers do not have an endless supply of quality aggregates. With limitations of the road building industry and the foreseeable economic growth projected for the City of Saskatoon, it is reasonable to expect that the unit costs of providing conventional pavement structures will continue to increase in Saskatoon. Presently, the primary conventional road building materials include well graded granular base material, subbase, crushed rock and a wearing surface of either conventional hot mix asphalt concrete (HMAC) or Portland cement concrete (PCC). To ensure long term pavement performance, quality aggregate sources are needed in all road design structural layers. Recent years have seen an increased need for substructure drainage systems, therefore increasing the need for high quality crushed rock. City of Saskatoon, like other urban centers, generates significant stock piles of concrete rubble annually. The primary objective of this research was to compare PCC material properties to those of conventional granular materials under realistic field state conditions. The second objective of this research was to validate the economic feasibility of using recycled PCC material within City of Saskatoon road structure through test section design and field test sections’ structural performance. Conventional and mechanistic material characterization was completed for recycled PCC well graded base course and recycled PCC drainage rock derived from PCC rubble, as well as conventional City granular base and drainage rock aggregates from typical City of Saskatoon stockpiles. Conventional testing completed on the samples included physical properties as required by COS aggregate specifications. Micro-Deval testing was also completed to compare the mechanical breakdown of the aggregates tested. Based on the results of the conventional tests performed, the recycled PCC well graded base and the recycled PCC drainage rock were found to meet COS base and drainage rock specifications, respectively. The recycled PCC well graded base material, recycled PCC drainage rock, COS granular base, and recycled PCC well graded base stabilized with different percentages of cement and slow setting type one (SS-1) asphalt emulsion were the research materials mechanistically tested. These materials were mechanistically tested using triaxial frequency sweep characterization to derive the mechanistic material constitutive relations across all the materials. Five repeat samples were gyratory compacted and tested at room temperature using the rapid triaxial testing. To characterize climatic durability, all the samples were moist cured for 28 days, characterized using the rapid triaxial test; then vacuum saturated and then characterized again using the rapid triaxial test. The mechanistic properties measured for the PCC material showed better climatic durability compared to those measured for the virgin aggregates, particularly after climatic durability testing. Prior to vacuum saturation, the conventional COS granular base had a peak dynamic modulus of 457 MPa. Under the same testing conditions, recycled PCC well graded base unstabilized had a stiffness of 1081 MPa; the stabilized PCC samples with two percent cement had a dynamic modulus of 1542 MPa. The radial micro strain and Poisson’s ratio were reduced for well graded PCC materials both unstabilized and stabilized compared to the conventional COS granular base. The conventional granular base had a peak radial micro strain of 194 compared to the untreated recycled PCC well graded base peak radial micro strain of 54 at the same testing parameters of low stress state at a testing frequency of 10 Hz prior to vacuum saturation. The conventional COS granular base samples failed under high deviatoric stress state at a 0.5 Hz testing frequency prior to vacuum saturation, whereas the PCC materials survived all testing frequencies and stress states. However, after vacuum saturation, the unstabilized recycled PCC well graded base samples failed under high stress state under a 10 Hz testing frequency. To validate field structural performance, two road structures within the City of Saskatoon were used as test sections in which recycled PCC drainage rock was used as a structural drainage layer. The first test section was constructed in the east bound lane of Marquis Drive, and the second was completed at the University of Saskatchewan. Prior to construction of both the Marquis Drive and North Road test sections, both sections were tested for peak surface deflections using the heavy weight deflectometer. Segment 1 of Marquis Drive had an average pre construction surface deflection of 1.85 mm under a primary weight limit. Section 1 of North Road had an average pre construction surface deflection of 1.17 mm under primary weight limit. After construction was complete on both test sections using recycled materials including a PCC drainage layer, HWD testing showed post construction peak deflections were significantly lower than the deflections measured pre construction. Recycled PCC well graded base material performed well in mechanistic laboratory analysis. However, the material was not field tested in this research. Mechanistic laboratory and field analysis indicated that recycled PCC drainage rock aggregates met structural performance requirements. The capital cost analysis showed that using recycled PCC drainage rock can reduce the overall cost of road rehabilitation projects when compared to using conventional virgin aggregates, particularly crushed drainage rock. The Marquis Drive section had a cost savings of $89,000, and the University of Saskatchewan section had a cost savings of $75,800 when recycled materials were used in lieu of virgin aggregates to rehabilitate the pavement structure. In addition, no PCC was disposed of in the landfill, saving the City of Saskatoon tipping fees and extending the life of the landfill. This research showed that the crushed PCC rubble is both technically and economically feasible to use as high quality aggregates in City of Saskatoon streets. Based on the findings of this research, the City of Saskatoon should pursue the use of recycled PCC rubble aggregates in urban road construction.

Diss. Linköping : Linköpings universitet, 2006.

The proper densification of the separate pavement layers forms an integral part of road construction. Many problems, are, however, experienced in this area. Because of a lack of knowledge the compaction of untreated roadbuilding materials in problem situations is usually approached on a ''trial and error'' basis rather than basing possible solutions on scientific evidence of the collective influence of the material properties and site conditions. The purpose of the study was to place the compaction of untreated roadbuilding materials on a more scientific basis. An investigation was therefore launched to determine the effect of measured material properties on their compactability. A non-standard vibratory compaction test was used to compact the samples in one layer. New test parameters to quantify the shape and texture of the material were also developed, namely the shakedown bulk density and the shape factor. The CBR values of the materials at moulding moisture content were determined for each material for a range of densities and moisture contents. The maximum dry densities (MOD) (vibratory and mod. AASHTO) and optimum moisture content (OMC) (vibratory and mod. AASHTO) were also determined. The measured values were then evaluated in terms of the following physical properties of the materials: grading, Atterberg limits, linear shrinkage, shakedown bulk density (SBD), loose bulk density (LBO), shape factor (SF) and specific rugosity (Srv). In the extensive laboratory study of 21 different untreated roadbuilding materials, varying from TAB classes A-7-6 to A-1, it was found that both the maximum dry densities and moisture regimes can be quantified in terms of the grading, liquid limit and linear shnnkage of the materials. These relations were modelled by means of regression analysis. Besides this a general bearing capacity model was found for all these materials where the CBR is a function of the dry density and moisture content of the material. This model was further refined to take account of the influence of shape and texture of the particles so that it is possible to determine reasonable estimates of the bearing capacity for a range of densities and moisture contents from the grading, Atterberg limits, linear shrinkage, shakedown bulk density and shape factor. This investigation has shown that physical laws govern both the compactability and bearing capacity of untreated roadbuilding materials, irrespective of their composition or nature, making it possible to approach the compaction of untreated roadbuilding materials in a more generalised manner. / Thesis (PhD)--University of Pretoria, 1991. / gm2014 / Civil Engineering / unrestricted

No description available.

This MSc (Eng) Investigational Project Report entails the evaluation of the Sekhukhuneland Development Programme (SDP). The SDP is a joint initiative of the Donaldson Trust and the Research Centre for Employment Creation in Construction (WORK). Its objective is: to increase the use of labour-intensive methods in the rehabilitation and maintenance of rural roads and other infrastructure in order to contribute to employment generation, skills development, provision of infrastructure and poverty alleviation. In order to achieve this objective an “Association not for gain” called LITE (Labour Intensive Training and Engineering) was formed; the Donaldson Trust provided the finance, and the expertise was provided by The Research Centre (WORK) but with additional support by Employment Intensive Engineering Consultants (EIEC). As the contracting organisation evolved from nothing into the training and engineering company LITE, the number of employees rose from none to fourteen. The University of the Witwatersrand provided a number of students to the project site at Mohlaletse in Sekhukhuneland where they provided voluntary assistance as part of their studies. Many of these students were from the University of Twente in the Netherlands, and it was largely due to their commitment that the project enjoyed such healthy growth. Considering the meagre resources this growth was a remarkable achievement, and it was made possible, not only through the efforts of the students, but also through the acceptance and support of the community. This support included providing accommodation for both students and site management. With a minimum of resources local community members were trained and employed by the SDP over a prolonged period of three years. The SDP evolved into a new programme, the Mohlaletse Youth Service Programme (MYSP), funded by the Umsobomvu Youth Fund. Of the R1.700.000 donated to the SDP, R1.690.000 was used during the evaluated period. Of this sum approximately 50% was spent directly within the Mohlaletse and Monametse community. The SDP consisted out of three main phases. The organisation evolved during the first two phases from no organisation into LITE Section 21, an organisation that could deal with training and engineering based on a strong labour-intensive focus. During the Pilot Phase the programme focused on establishing contact with the community and proving that labouriii intensive construction method could work. The next phase was the Training Phase where the necessary team leaders were trained to perform a variety of construction techniques. These techniques range from drainage structure to roads and buildings. The last phase is the Construction Phase during which the construction went ahead as planned using fully trained team leaders from the local community. The total setting of the SDP was as follows: SDP Phases SDP Periods Organisation SDP Projects - Pilot Phase: Period 1999H None Period Projects Period 2000A Point-of-Fact (Pty) Ltd Period Projects - Training Phase: Period 2001A Period Projects Mohlaletse Money-Cant-Buy Section 21 Period Projects Monametse Period 2001H Period Projects Mohlaletse LITE - Section 21 Period Projects Monametse Period Project Compound - Construction Phase: Period 2002H Period Projects Mohlaletse Period Projects Monametse Period Project LITE-House and LITE-School The main reason for the success has been the substantial involvement of the local Mohlaletse community and the acceptance of the Site Management within the Community. Within the constraints of the programme definition and objectives, the SDP has been a success to its sponsors and beneficiaries. Major problems were encountered within the fields of Labour-Intensive Construction Methods and the Project Management Areas of Knowledge. These should be taken into consideration when a new Constructing-Training Programme is started in future.