Alternative Construction Methods Research Articles

Construction of property price indices

PurposeThe purpose of this paper is to examine if temporal aggregation matters in the construction of house price indices and to test the accuracy of alternative index construction methods.Design/methodology/approachFive index construction models based on the hedonic, repeat‐sales and hybrid methods are examined. The accuracy of the alternative index construction methods are examined using the mean squared error and out‐of‐sample technique. Monthly, quarterly, semi‐yearly and yearly indices are constructed for each of the methods and six null hypotheses are tested to examine the temporal aggregation effect.FindingsOverall, the hedonic is the best method to use. While running separate regressions to estimate the index is best at the broader level of time aggregation like the annual, pooling data together and including time dummies to estimate the index is the best at the lower level of time aggregation. The repeat‐sales method is the least preferred method. The results also show that it is important to limit time to the lowest level of temporal aggregation when construction property price indices.Practical implicationsThis paper provides alternative method, the mean squared error method based on an out‐of‐sample technique to evaluate the accuracy of alternative index construction methods.Originality/valueThe introduction of financial products like the property derivatives and home equity insurances to the financial market calls for accurate and robust property price indices. However, the index method and level of temporal aggregation to use still remain unresolved in the index construction literature. This paper contributes to fill these gaps.

A Robust Multiquadric Method for Digital Elevation Model Construction

The multiquadric method (MQ) with high interpolation accuracy has been widely used for interpolating spatial data. However, MQ is an exact interpolation method, which is improper to interpolate noisy sampling data. Although the least squares MQ (LSMQ) has the ability to smooth out sampling errors, it is inherently not robust to outliers due to the least squares criterion in estimating the weights of sampling knots. In order to reduce the impact of outliers on the accuracy of digital elevation models (DEMs), a robust method of MQ (MQ-R) has been developed. MQ-R includes two independent procedures: knot selection and the solution of the system of linear equations. The two independent procedures were respectively achieved by the space-filling design and the least absolute deviation, both of which are very robust to outliers. Gaussian synthetic surface, which is subject to a series of errors with different distributions, was employed to compare the performance of MQ-R with that of LSMQ. Results indicate that LSMQ is seriously affected by outliers, whereas MQ-R performs well in resisting outliers, and can construct satisfactory surfaces even though the data are contaminated by severe outliers. A real-world example of DEM construction was employed to evaluate the robustness of MQ-R, LSMQ, and the classical interpolation methods including inverse distance weighting method, thin plate spline, and ANUDEM. Results showed that compared with the classical methods, MQ-R has the highest accuracy in terms of root mean square error. In conclusion, when sampling data is subject to outliers, MQ-R can be considered as an alternative method for DEM construction.

Quantum effects in the abstraction reaction by H atoms of primary and secondary hydrogens in n-C4H10: a test of a new potential energy surface construction method

Recently, von Horsten et al. suggested an efficient method to construct two dimensional potential energy surfaces (PESs) for use in quantum scattering simulations, in which they utilised the minimum energy path (MEP) and assumed harmonic behaviour of the PES near the MEP. In the same paper, the authors applied this method to various H-abstraction reactions from C1-C3 alkane molecules. In this work we demonstrate an alternative PES construction method, and apply it to the more challenging H-abstraction from n-C(4)H(10) reactions. The geometry optimizations and frequency calculations are done at the MP2/cc-pVTZ level of theory, while the energies are calculated with the CCSD(T) method with the same basis set. The calculations give adiabatic energy barrier heights of 45.9 kJ mol(-1) and 34.4 kJ mol(-1) for the primary and secondary hydrogens in n-C(4)H(10). When compared to purely classical transition state theory, quantum scattering calculations show that quantum tunnelling and zero-point effects have large contributions at low temperatures, typically below 500 K. The branching ratio study suggests that the abstraction of secondary hydrogen in n-C(4)H(10) dominates the overall reaction rate at low temperatures. The rate constants for the two abstraction channels become more comparable as the temperature increases.

Horizontal Directional Drilling: A Green and Sustainable Technology for Site Remediation

Sustainability has become an important factor in the selection of remedies to clean up contaminated sites. Horizontal directional drilling (HDD) is a relatively new drilling technology that has been successfully adapted to site remediation. In addition to the benefits that HDD provides for the logistics of site cleanup, it also delivers sustainability advantages, compared to alternative construction methods.

Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts

AbstractCrosshole Sonic Logging (CSL) of drilled shafts requires 1.5-in (38-mm) or 2-in (51-mm) I.D. sonic access tubes to be installed inside the steel reinforcement cage. The sonic access tubes do not contribute to the structural capacity of the drilled shaft. The proposed use of Ischebeck TITAN T73/56 CSL/Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts (patent pending) is discussed as an alternative method of construction and CSL probe access. The T73/56 hollow threaded rebar/sonic access tube performs as a high strength rebar while at the same time creating a 2.2-in (56-mm) I.D. sonic access tube. The deformed high strength hollow bar provides better adhesion to concrete thus reducing the problem of debonding associated with smooth PVC and steel pipe. A cost comparison using conventional rebar with added sonic access tubes is discussed. The use of T73/56 CSL/Hollow Threaded Rebar as a value engineering alternative can re...

Laparoscope‐Assisted Creation of a Neovagina Using Pedicled Ileum Segment Transfer

To present our experience of vaginal reconstruction with the use of a pedicled ileum segment and laparoscope assistance, and to analyze its complications and long-term anatomic and functional results. The abdominal and perineal approaches were performed simultaneously with the patient in a special position. Under the guidance of laparoscopy, the target ileal segment was harvested and transposed down to the perineum through an artificial tunnel between the bladder and the rectum. A silicon vaginal tutor was introduced into the vaginal cavity and maintained all day long for 2-3 months. The complications and the anatomical and functional results were summarized and analyzed. From February 2002 to June 2010, 82 patients underwent laparoscope-assisted total vaginal reconstruction with a pedicled ileum segment at our department. Complications developed in 16 of 82 patients, including rectum and/or bladder injury during operation, acute renal failure, delayed healing of the ileocutaneous anastomosis, introital stenosis, and partial or complete intestinal obstruction. The abdominal cutaneous scar was acceptable after the surgery. The vulva was not altered, which was especially significant for patients with congenital vaginal atresia. The neovagina was patent, soft, moist, and flexible. The mean width and depth of the neovagina at the latest postoperative visit measured 3.2 and 15 cm, respectively. The favorable long-term anatomical and functional results demonstrate that our technique is ideal for patients with congenital vaginal atresia or patients who need secondary vaginal reconstruction. For the primary male-to-female transsexuals or hermaphrodites, it can be an alternative method for vaginal construction.

Performance Assessment of On-Grade Horizontal Directional Drilling

Although horizontal directional drilling (HDD) has been widely accepted and used for installing gas lines, waterlines, and telecommunication cables, its applications to gravity-flow sewer lines have been limited. One primary reason is the difficulty with maintaining critical grades essential for gravity-flow sewer systems when using the conventional HDD tracking methods. Recently, advancements made in tracking systems, electronics, and operational techniques have made this HDD technology a technically feasible and an economically attractive method for installing on-grade underground pipes in many situations. This paper presents a newly developed HDD technology in terms of its technical capabilities and economic feasibilities compared with the traditional open-cut method on the basis of two real-scale case studies. Installation errors are quantitatively analyzed and discussed, and a general set of boundary site conditions for the application of this new technology is also discussed. The detailed analysis of the two case studies demonstrates that the on-grade HDD method could be a very attractive alternative construction method for gravity-flow sewer pipelines when some favorable site conditions are available.

A method of DEM construction and related error analysis

The concept and the computation of terrain representation error (ETR) are investigated and total DEM error is presented as an accuracy index for DEM evaluation at a global level. A promising method of surface modelling based on the theorem of surfaces (SMTS) has been developed. A numerical test and a real-world example are employed to comparatively analyze the simulation accuracy of SMTS and the classical interpolation methods, including IDW, SPLINE and KRIGING performed in ARCGIS 9.1 in terms of sampling and interpolation errors and of total DEM error. The numerical test shows that SMTS is much more accurate than the classical interpolation methods and ETR has a worse influence on the accuracy of SMTS than those of the classical interpolation methods. In a real-world example, DEMs are constructed with SMTS as well as the three classical interpolation methods. The results indicate that, although SMTS is more accurate than the classical interpolation methods, a real-world test indicates that there is a large accuracy loss. Total DEM error composed of, not only sampling and interpolation errors, but also ETRs can be considered as a good accuracy measure for DEM evaluation at a global level. SMTS is an alternative method for DEM construction.

Construction of geogrid encased stone columns: A new proposal based on laboratory testing

Geogrid encasement has recently been investigated to provide an alternative and perhaps stiffer option to the now established method of geotextile encased columns (GECs). To construct geogrid encasement, the geogrid is typically rolled into a sleeve and welded using a specialized welding frame. However, the process is unlikely to be economical for site construction and therefore an alternative method of encasement construction was investigated in this paper. The technique comprises overlapping the geogrid encasement by a nominal amount and relying on interlock between the stone aggregate and section of overlap to provide a level of fixity similar to welding. A series of small-scale tests were initially used to investigate the technique, followed by medium-scale compression tests using different geogrids and typical stone column aggregates. The results of testing indicate that the “method of overlap” provides a simple and effective method of encasement construction, providing a level of fixity similar to welding. A full circumference of overlap should generally be adopted to achieve adequate fixity. Biaxial geogrids are best suited to the technique, with increased encasement stiffness resulting in increased column capacity and column stiffness. Higher strength geogrids are also more robust, providing a greater resistance to cutting from pieces of angular crushed rock. Site trials are recommended for final confirmation of the technique.

Energy, Emissions, Material Conservation, and Prices Associated with Construction, Rehabilitation, and Material Alternatives for Flexible Pavement

Today, public agencies responsible for roads, streets, and highways are experiencing significant increases in the price of construction operations and asphalt binder availability; they are also experiencing limited available funds and the uncertainty of inflation. Those concerns are coupled with significant pressure to build, maintain, and rehabilitate “green,” and agencies must look to alternative construction, rehabilitation, and maintenance methods as well as alternative materials that deliver on both of these seemingly different forces. Life-cycle assessment was used to evaluate roadway construction activities. Life-cycle assessment is similar to life-cycle cost analysis, except that environmental impact is considered over the analysis period. Life-cycle assessment includes energy consumption, emissions generation, and natural resource consumption in addition to price of the activity. All activities evaluated were compared with conventional materials and means of construction. Materials evaluated specific to hot-mix asphalt included reclaimed asphalt pavement, asphalt shingles, and warm-mix asphalt. Aggregate base stabilization and subgrade treatments were evaluated as part of a low- and high-traffic-volume facility. The final evaluation considered rehabilitation and maintenance activities that focused on in-place recycling, such as hot in-place and cold in-place recycling. In most instances, these activities can reduce energy consumption and emissions generation and can conserve natural resources (aggregate and asphalt binder), plus offer the benefit of reducing the price of construction. These materials and technologies show promise in helping agencies meet the rising price of construction while addressing public concern for the environment.

Life-Cycle Case Study Comparison of Permeable Reactive Barrier versus Pump-and-Treat Remediation

A permeable reactive barrier (PRB) is a passive remediation technology, which over decades of use, may reduce lifetime environmental impacts when compared with a conventional pump-and-treat system (PTS). Greater material production requirements to install PRBs may offset the expected reductions in operational phase impacts and the trade-offs can be investigated in a life-cycle assessment (LCA). The life-cycle environmental impacts of a zerovalent iron (ZVI) containing PRB with a funnel and gate configuration and a PTS were compared in a case study. Potential impacts of the model PRB are driven by the ZVI reactive medium and the energy usage during construction, while for the PTS they are driven by the operational energy demand. Medium longevity governed the magnitude of the potential PRB impacts and the extent to which it was optimal relative to the PTS. Even at conservatively low estimates of longevity, the PRB offers significant environmental advantages in impact categories of human health and ozone depletion. The minimum ZVI longevity for PRB benefit over the PTS system in all impact categories was 10 years. Suggested PRB design innovations to reduce environmental impacts include the development of alternative reactive media and construction methods.

Self-assembly and self-repair of arbitrary shapes by a swarm of reactive robots: algorithms and simulations

Self-assembly of active, robotic agents, rather than of passive agents such as molecules, is an emerging research field that is attracting increasing attention. Active self-assembly techniques are especially attractive at very small spatial scales, where alternative construction methods are unavailable or have severe limitations. Building nanostructures by using swarms of very simple nanorobots is a promising approach for manufacturing nanoscale devices and systems. The method described in this paper allows a group of simple, physically identical, identically programmed and reactive (i.e., stateless) agents to construct and repair polygonal approximations to arbitrary structures in the plane. The distributed algorithms presented here are tolerant of robot failures and of externally-induced disturbances. The structures are self-healing, and self-replicating in a weak sense. Their components can be re-used once the structures are no longer needed. A specification of vertices at relative positions, and the edges between them, is translated by a compiler into reactive rules for assembly agents. These rules lead to the construction and repair of the specified shape. Simulation results are presented, which validate the proposed algorithms.

Visualizing high-rise building construction strategies using linear scheduling and 4D CAD

Project teams face ever increasing pressure to deliver projects as quickly as possible. To meet these demands, contractors are faced with the need to explore various construction strategies in order to meet delivery dates, and to assure themselves as to the achievability and quality of a schedule. Various visual representations of a project's schedule and associated information combined with visual representations of the project in progress, i.e. 4D CAD, can assist with these tasks of identifying effective construction strategies for shortening project duration, assessing their workability, and judging schedule quality. Such visual representations aid communication amongst project staff and facilitate brain-storming, and, implemented well they can provide clear, fast, and multi-dimensional feedback to the project team. In this paper, we describe aspects of our work which is directed at formulating a dynamic visualization environment that links 3D CAD, a generalization of traditional CPM which embraces linear scheduling, dual product representations (scheduling and CAD system) and their mapping onto each other, and schedule and CAD graphics in a manner which facilitates the relatively rapid exploration of alternative construction method and scheduling strategies for large scale linear projects (e.g. high-rise buildings, bridges, etc.). Requirements of such an environment include quickness, treating scale, working at multiple levels of detail, dealing with design variability, and realistic representation of the work. Use is made of a realistic example to highlight aspects of our approach and identify important issues that must be addressed if a visualization environment useful for construction professionals is to be developed.

Using buttress walls to reduce excavation-induced movements

The buttress wall is an alternative construction method for protection of adjacent buildings during excavation. It is generally recognised, but not verified, that the method has good effects in reducing wall movement and ground settlement, because buttress walls behave as T-shaped concrete beams, which possess comparatively larger stiffness than two-dimensional diaphragm walls. However, the behaviour of buttress walls in excavations is not fully understood, because of a lack of well-monitored case histories and systematic studies. In this study, the effectiveness of buttress walls in reducing wall deflection and ground settlement is evaluated through observed behaviour of a case history, and through finite element studies. The case study indicates that the use of buttress walls in a deep excavation can significantly reduce the deflection of a diaphragm wall. Effective prediction of the behaviour of the buttress wall can be achieved using the three-dimensional finite element method. Parametric studies reveal that deflection of the diaphragm wall is strongly influenced by the condition of the restraint at the bottom of the buttress walls, and by the number of buttress walls. As long as the buttress wall bottom is well restrained, and reasonable numbers of buttress walls are installed, wall deflection can be considerably reduced.

Go Trenchless to Combat Excavation Costs

This article discusses alternative construction methods such as horizontal directional drilling (HDD) and pipe bursting for installing and replacing underground pipelines. The article describes how the two technologies work, along with common pipe materials for trenchless technologies.

Bridging the gap between research and standards

Standards were developed and continued to exist to allow commerce. Minimum specifications are set for materials, and standard test methods are used to determine compliance with the specification limits. Materials specifications for cements and other concrete ingredients are referenced in concrete specifications, which are in turn referenced in building codes. A common complaint about standards is that they are not responsive to new research findings and lag behind new developments in materials and construction practices. However, standards do evolve over time as needs are seen to improve or add new tests methods or to set new specification limits. Another complaint is that historically prescriptive specifications should be switched to performance-based specifications so as not to limit development of alternative materials and construction methods. It should be noted that many standards writing organizations such as ASTM and CSA develop consensus standards, where volunteer members provide a balanced representation of a range of different interests, typically including both Producers and Users of a standard as well as General and Governmental agency interests. As a result of this balance, the wishes of one group alone can not unilaterally change standards against the majority interests. In this contribution, some both historical and recent developments in standards relating to cementitious materials are addressed, along with some thoughts on future directions. While some international standards are mentioned, it is acknowledged that this paper is largely limited to discussion of North American standards.

Geosynthetic-wrap around revetments for shore protection

Geosynthetic structures for shore protection have demonstrably lower construction and lifetime costs than those of hard structures. This paper outlines the recent development of a geosynthetic structure that is commonly used for shore protection: geotextile wrap-around revetments (GWRs). Its advantages are also explained. Model tests described in this paper show that these structures are stable against wave action and that their stability can be increased with some simple modifications. Additionally, GWRs have been shown to adapt extremely well against differential settlement and scour erosion. Knowledge obtained from model tests has facilitated the creation of modified design charts. Efficiency of these systems against storm surges, rising sea level, and tsunami is also discussed. Analyses show that many uncertainties involving these structures remain, but that geosynthetic structures should not be regarded as an alternative shore construction method. Rather, they are a preferable solution for numerous coastal problems.

A novel approach for Roux limb construction via the lesser sac

Exposure of the ligament of Treitz for Roux limb construction during laparoscopic gastric bypass requires either division or displacement of the omentum. Factors compromising this exposure include: (1) a bulky omentum, (2) hepatomegaly, (3) adhesions between the omentum and lower abdominal wall or pelvic contents and (4) inability to identify the transverse colon because of overlying adipose tissue. The lesser sac approach is an alternative method for Roux limb construction during laparoscopic gastric bypass when access to the inframesocolic abdomen is difficult. In this technique the lesser sac is entered through the gastrocolic ligament. The transverse mesocolon is then opened and the ligament of Treitz is identified. The jejunum is pulled into the lesser sac and the Roux limb is constructed. The jejunojejunostomy is reduced into the inframesocolic compartment, the mesenteric defects are closed, and the remaining portion of the procedure is completed. This technique provides an alternative method for completion of a laparoscopic gastric bypass in patients who would otherwise require more extensive surgery.

MANAGERIAL AND ECONOMIC OPTIMISATIONS FOR PREFABRICATED BUILDING SYSTEMS

This paper deals with new realisations of research, scientific development, managerial and economic optimisations – a prefabricated building systems. In the literature, all scientific fields are worked out based on efficiencies, costs, benefits, choice of execution design, technical demands, aesthetical point of view, as well as the total economics. In the present example of a school building for communities in developing countries, the following criteria have been regarded: the optimal superstructure of prefabricated concrete building systems; the particularity of developing countries (eg the climate, the political and economic conditions); the time for construction and necessary innovative developments for an economically optimised superstructure. In addition, alternative construction methods and costs for a simple but variable system which can be adapted to changing functions are suggested.

Life-Cycle Economic Evaluation of Alternative Road Construction Methods on Low-Volume Roads

The province of Saskatchewan has the largest number of public roads per capita in Canada and one of the largest in the world. Over the past decade, pressures on the road network have increased, resulting in accelerated road damage and increased demand to upgrade portions of the highway network. To address transportation infrastructure sustainability issues, Saskatchewan Highways and Transportation (DHT) and Pavement Scientific International, Inc., are researching more cost-effective methods. The research work involves evaluating the technical and economic feasibility of undertaking alternative road construction techniques. A critical component of this research effort is to evaluate the economic feasibility associated with different road construction techniques. The ability to perform whole-life economic analysis associated with long-term infrastructure assets is important to long-term sustainability. By comparing the present value of initial construction and future preservation costs across different road structures and technologies, an accurate assessment of construction and design options is achievable. On the basis of performance predictions and projected structural performance, resource allocation can be optimized more reliably across limited resources and alternative road strengthening systems, providing technically sound solutions that are more economically attractive. With an ability to predict whole life-cycle performance on the basis of future maintenance treatments, road managers can more reliably assess alternative surfacing and structural preservation strategies. The primary focus of this paper is to demonstrate the economic considerations undertaken in evaluating alternative road design and construction methods. This longer-term evaluation approach allows strategic investments in highway infrastructure and allows DHT and other agencies to consider innovative road structural rehabilitation and management strategies more effectively.