An integrated computer model for time and cost optimisation has been developed for multi-storey reinforced concrete office buildings. The development of the model has been based on interviews completed with Planners, Estimators and Researchers within 2 of the top 20 (in terms of turnover) UK main contractors, and on published literature, bar charts and bills of quantities of concrete framed commercial buildings. The duration and cost of construction of a typical multistorey reinforced concrete office building is calculated through the first part of the integrated model, i.e. the simulation model. The model provides a set of choices for the selection of materials and plant and possible methods of work. It also requires the user to input the quantities of work, gang sizes and the quantity of plant required, lag values between activities, output rates, unit costs of plant, labour costs and indirect costs. A linked bar chart is drawn automatically by using the data available from the simulation model. The second part of the model, (optimisation) uses the data provided by the simulation part and provides sets of solutions of time vs. cost from which the minimum project cost corresponding to the optimum project duration is calculated under the given schedule restrictions. Linear programming is used for the optimisation problem. The objective function is set to be the minimisation of the project cost which is the total of the direct costs of all the activities creating the project and the indirect costs of the project. The constraints are formulated from the precedence relationship, lag values, and normal and crash values of time and cost for the activities supplied by the simulation model. The simulation part has been validated by comparing and contrasting the results with those methods and practices adopted by commercial planners and estimators. The validation of the optimisation part has been undertaken by plotting time-direct cost curves from the results and checking the convexity of the curves. Additionally, the validation procedures included taking account of the opinions of practitioners in the industry on the practical and commercial viability of the model.

Lighting simulation contribute readily to the synthesis of high performance lighting designs. Unfortunately there exist several issues impeding the pervasive use of lighting simulation, including: Most of the time in preparing lighting simulations is spent towards the input of existing but non-interoperable information between different tools. Lighting simulation tools do not complement integrated building design processes where the design solution is progressively developed in multiple disciplines concurrently; lighting simulation tools require design information (attributes) that may not yet be defined, and is non-interoperable with other tools. . Disparate tools with vastly different technical approaches available for different stages of the building design process do not allow consistent or meaningful performance comparisons between design versions, and similarly makes design performance progress tracking between design versions difficult. Lighting simulation tools provide radiance and irradiance values as simulation results, and much time and manual effort is required to process these results into operative information, information that is directly applicable in making design decisions. Lighting simulation tools employ outdated rendering techniques that are inadequate in evaluating highly-reflected irradiance, a typical feature in high performance building designs. While there remain other shortcomings in lighting simulation tools as identified by contemporary research3, the issues above relate closely to the overall effort and time-cost factors attributed to using simulation tools, which has been consistently identified as obstacles towards using simulation tools. This research seeks to reduce the effort and time-cost required to conduct lighting simulation by addressing the issues above. Case studies of actual design scenarios are used to establish quantitatively the effort and time costs baselines for comparison. The effort and time reduction goal is structured as the following objectives in a new lighting design support tool: Reduce the time and effort to set up and conduct lighting simulation by using interoperable information (building information models) from design modeling tools. Complement integrated design processes by supporting design models of varying completeness5, in a format that is interoperable with tools from other disciplines in the design team. All information, including assumptions, must be consistent across all disciplines. Provide ability to use performance metrics and consistent technical approaches throughout design stages, regardless of completeness of design model. Provide operative information with minimum user effort. Implement a first principle-based rendering technique that handles high performance building designs well, and produce simulation results within reasonable time constraints. By meeting these objectives, the new lighting design tool is able to automate much of the previously manual, time-consuming, and disparate efforts in lighting simulation, thus reducing the effort and time-cost. By sharing interoperable information with other tools across the design team, the new lighting design tool is integrated. The new tool is also scalable in being able to support models of varying completeness throughout all design stages.

In pursuance of decreasing costs, both the client and the contractor would strive to speed up the construction project. However, accelerating the project schedule will impose additional cost and might be profitable up to a certain limit. Paramount for construction management, analyses of this trade-off between duration and cost is hailed as the time-cost trade-off (TCT) optimization. Inadequacies of existing commercial software packages for such analyses tied with eminence of discretization, motivated development of different paradigms of particle swarm optimizers (PSO) for three extensions of discrete TCT problems (DTCTPs). A sole-PSO algorithm for concomitant minimization of time and cost is proposed which involves minimal adjustments to shift focus to the completion deadline problem. A hybrid model is also developed to unravel the time-cost curve extension of DCTCPs. Engaging novel principles for evaluation of cost-slopes, and pbest/gbest positions, the hybrid SAM-PSO model combines complementary strengths of overhauled versions of the Siemens Approximation Method (SAM) and the PSO algorithm. Effectiveness and efficiency of the proposed algorithms are validated employing instances derived from the literature. Throughout computational experiments, mixed integer programming technique is implemented to introduce the optimal non-dominated fronts of two specific benchmark problems for the very first time in the literature. Another chief contribution of this thesis can be depicted as potency of SAM-PSO model in locating the entire Pareto fronts of the practiced instances, within acceptable time-frames with reasonable deviations from the optima. Possible further improvements and applications of SAM-PSO model are suggested in the conclusion.

In this thesis, meta-heuristic algorithms are developed to obtain optimum or near optimum solutions for the time-cost-resource trade-off and resource leveling problems in project scheduling. Time cost trade-off, resource leveling, single-mode resource constrained project scheduling, multi-mode resource constrained project scheduling and resource constrained time cost trade-off problems are analyzed. Genetic algorithm simulated annealing, quantum simulated annealing, memetic algorithm, variable neighborhood search, particle swarm optimization, ant colony optimization and electromagnetic scatter search meta-heuristic algorithms are implemented for time cost trade-off problems with unlimited resources. In this thesis, three new meta-heuristic algorithms are developed by embedding meta-heuristic algorithms in each other. Hybrid genetic algorithm with simulated annealing presents the best results for time cost trade-off. Resource leveling problem is analyzed by five genetic algorithm based meta-heuristic algorithms. Apart from simple genetic algorithm, four meta-heuristic algorithms obtained same schedules obtained in the literature. In addition to this, in one of the test problems the solution is improved by the four meta-heuristic algorithms. For the resource constrained scheduling problems / genetic algorithm, genetic algorithm with simulated annealing, hybrid genetic algorithm with simulated annealing and particle swarm optimization meta-heuristic algorithms are implemented. The algorithms are tested by using the project sets of Kolisch and Sprecher (1996). Genetic algorithm with simulated annealing and hybrid genetic algorithm simulated annealing algorithm obtained very successful results when compared with the previous state of the art algorithms. 120-activity multi-mode problem set is produced by using the single mode problem set of Kolisch and Sprecher (1996) for the analysis of resource constrained time cost trade-off problem. Genetic algorithm with simulated annealing presented the least total project cost.

In project scheduling, the activity durations can often be reduced by dedicating additional resources. Time/Cost Trade-off Problem considers the compromise between the total cost and project duration. The discrete version of the problem assumes a number of time/cost pairs, so called modes, and selects a mode for each activity. In this thesis we consider the Discrete Time/Cost Trade-off Problem. We first study the Deadline Problem, i.e., the problem of minimizing total cost subject to a deadline on project duration. To solve the Deadline Problem, we propose several optimization and approximation algorithms that are based on optimal Linear Programming Relaxation solutions. We then analyze the problem of generating all efficient solutions, and propose an approach that uses the successive solutions of the Deadline Problem. Our computational results on large-sized problem instances have revealed the satisfactory behavior of our algorithms.

In this thesis, we consider a discrete time/cost trade-off problem with a single nonrenewable resource. We assume the resource is released at some prespecified time points and at some prespecified quantities. We also assume that the costs due to the activities are incurred at their completions. Our aim is to minimize total project completion time. We formulate the problem as a pure integer programming model. We show that the problem is strongly NP-hard. We find lower bounds by pure linear programming and mixed integer linear programming relaxations of the model. We develop three heuristic procedures using the optimal solutions of mixed integer linear program and pure linear program. The results of our computational study reveal the satisfactory performance of our heuristic procedures.

Construction projects in developing countries may suffer from time overruns, which are associated with cost overruns. This research project investigated both time and cost overruns on high-rise building projects in Dhaka, Bangladesh. Surprisingly, preliminary data analysis showed negligible cost overruns in comparison to time overruns. So, further analysis o f cost overruns was not considered in this thesis. This research project also investigated how the causes o f time-overruns can be mitigated. 72 time-overrun and 22 cost-overrun variables were identified through a literature review. These variables were taken as parameters and a personal interview survey was conducted with developers, consultants, contractors and project managers using semistructured questionnaire. A similar second survey was conducted using 22 measures, which can mitigate time- overruns. Data analysis involved the relative importance index to rank the variables, factors analysis to reduce variables to factors with minimum loss of data, stepwise regression to find links among factors in successive stages of construction process and multiple regression to explain delays in terms of factors. The main causes o f time-overruns were ‘cash flow’, ‘planning and scheduling deficiency’ and ‘design changes’. A scree graph identified 31 important variables that caused delays but factor analysis reduced these to 14 factors. Stepwise regression found no strong links among the factors to identify them as reasons for delay in successive stages of the construction project. A multiple regression model explained about 85% of the variance of the delays using eight factors. The main individual measures mitigating time-overruns were ‘improvement of cash flow’, ‘improvement o f communication and coordination among project participants’ and ‘development o f robust planning and scheduling instruments’. Factor analysis produced ten representative factors. Stepwise regression could not find strong links among factors mitigating time-overruns in successive stages of the construction project.

The negative impacts associated with highway pavement rehabilitation projects drove state highway agencies (SHAs) towards increased adoption of alternative contracting methods (ACMs) to accelerate the construction of such projects; hence, reducing these impacts on the travelling public. However, the application of such methods showed mixed results due to the lack of specific guidelines addressing the adoption of such methods and the selection of the best ACM for each project. This lack of guidelines stems from the lack of research studies examining the impact of each of these methods on the time/cost trade-off relationship in highway rehabilitation projects. Existing literature includes several studies aimed at developing generic and subjective guidelines based on past experiences that do not take into consideration the unique nature of each of these methods. Hence, this research study aimed at analyzing the SHAs’ decision making process regarding two of the most-widely used ACMs: Incentive/Disincentive (I/D) and Cost + Time (A+B) contracting methods, in order to support decision makers in choosing the most-suitable method for their projects. To this end, two models were developed in this dissertation to examine the time/cost trade-off for each method using simulation and regression analysis. Each model was validated against real-life projects and used to assign appropriate ID and “B” values based on the SHA’s desired duration reduction and available budget. Furthermore, a risk analysis module was developed to determine the most-likely duration reduction that the contractor can achieve for each project under each method. The developed models should help improve the decision making process regarding the selection and implementation of these methods in highway rehabilitation projects. For example, the models can help SHAs identify the minimum ID level that can be offered for each project and the expected duration that the contractors can bid on under the A+B contracting method. Finally, the models were contrasted and applied to real-life projects with different characteristics to verify existing guidelines and establish the candidate ACM for each project category. The findings of this study will benefit the society, SHAs, and the economy in general by optimizing the use of available time and money resources.

Bakgrunden till detta examensarbete har sin grund i den bostadsbrist som finns i Sverige idag och den allmänna debatten om ökat bostadsbyggande och långsamma planprocesser som pågår. I studien har två detaljplaner, med huvudändamål bostäder, i var och en av de tre kommunerna Botkyrka, Norrköping och Västerås djupgående analyserats, i syfte att bringa klarhet i vilka aktiviteter och komponenter som faktiskt ger upphov till tidsåtgång i detaljplaneprocessens olika skeden. Av studien, vars tillvägagångssätt baserats på dokumentanalyser och intervjuer, framgår att detaljplaneprocessen utifrån sin utformning samt uppbyggnad via plan- och bygglagen (PBL) tar ”tid”. Hur lång tid en process tar beror enligt studien på flera olika anledningar som kan ha med den specifika planen och/eller kommunen att göra. Resultatet av undersökningen visar på att det i ett tidigt skede är väldigt svårt att uppskatta tidsåtgången för en detaljplan, då alla planer till viss del är unika och då oförutsebara komponenter och aktiviteter vanligtvis dyker upp under processens gång. Tidsåtgången för detaljplaneprocessen, räknat från det att ett formellt planuppdrag ges till det att detaljplanen vinner laga kraft, har för de planer som studerats i arbetet kraftigt varierat mellan 21 månader till 7 år. I snitt har dock processen för samtliga planer endast aktivt bedrivits under 1,5 – 3 år. Anledningen till att arbetet med vissa detaljplaner avstannat eller fördröjts har bland annat med oerfarna byggherrars brist på kunskap, politisk oenighet, sena inspel och bristen på resurser att göra. Enligt studien är de aktiviteter som ger upphov till störst tidsåtgång i detaljplaneprocesserna framförallt kopplade till utredningsarbetet. Det handlar både om att det är många utredningar som behöver tas fram och att de tar tid. Av studien framgår att tidseffektiviseringar i planprocessen är önskvärt så länge kvalitén kan bibehållas och detaljplanernas genomförbarhet kan säkerställas. Bostadsbristen i regionerna och det höga trycket i kommunerna lyfts fram som aspekter till varför det är viktigt. De förslag till förbättringsåtgärder som framhålls i denna studie handlar bland annat om att få till stånd bättre former för tidig samverkan mellan involverade parter, att ge den strategiska planeringen större tyngd och att utreda mer i ett tidigt skede, att skapa tydliga kommunövergripande mål och prioriteringsordningar för detaljplaner samt förbättra kommunens system och arbetsrutiner. Utöver det omnämns även ett behov av att utöka kommunens resurser och att öka tydligheten i vilka beslut som behöver fattas politiskt och på vilken nivå samt om det finns beslut som kan delegeras till kommunernas förvaltningar. / The background of this master thesis stems from the housing shortage that exists in Sweden today and the general debate on increased housing and slow planning processes that are currently taking place. In this study an in-depth analysis of two detailed development plans in each of the three municipalities of Botkyrka, Norrköping and Västerås has been carried out, in order to shed light on which activities and components that give rise to time consumption in the various stages of the planning process. The study, which is based on document analysis and interviews, concludes that the Swedish planning process due to its overall design and by being regulated by the Swedish planning and building act (PBL) takes "time". How much time the process takes depends, according to the analysis, on several different reasons that may have with the specific detailed development plan and/or the municipality to do. The result of the case studies carried out in this master thesis shows that it’s very difficult in an early stage to estimate how much time that will be required in order to create a detailed development plan. The reason for this is that every plan is somewhat unique and that unforeseeable components and activities usually emerge during the process. The time-cost of the planning process for the detailed development plans studied in this master thesis varied greatly from 21 months to 7 years. On average, however, the process for all the plans was only actively pursued during 1,5 - 3 years. The reason that the development of some of the plans was delayed or postponed has to do with, among other things, inexperienced developers lack of knowledge with regards to the planning process, political disagreements, belated demands for additional investigations and shortage of staff. According to this study, conducting surveys and investigations are the most time consuming activities within the planning process. It is a combination of many surveys needed to be carried out and that each one of them takes time to complete.    The result of this study shows that more time-efficient planning processes are desirable as long as the quality can be maintained and the feasibility of the detailed development plans can be guaranteed. The housing shortage in the regions and the high pressure to draw up plans and build homes in the municipalities are brought up as aspects of why it is important. The improvements that are suggested in the study involves, among others things, establishing better forms of early collaboration between all parties involved, giving the strategic planning greater weight and conducting more surveys in an early stage, creating clear common goals and priorities within the municipality's and furthermore improve the municipality's systems and working practices. In addition, it is suggested that the municipality's resources should be extended and that there should be an increased transparency regarding which decisions in the planning processes that need to be made politically and at what level, and if there are decisions that can be delegated to the municipality’s administrations.

Many private households spend considerable amounts of time accessing water, for instance by walking to and queuing at public access points, or by filling storage vessels at taps with low flow rates. This time has an opportunity cost, which can be substantial and may impact which water services and quantities of water households demand. In a novel form of diary study, we gathered detailed water consumption and time use data from 50 households in five informal settlements of the Indian metropolis Pune, accompanied by a household survey and in-depth interviews. With the data, we characterize water collection behaviors and assign monetary values to water procurement time. We statistically analyze the effects of time cost on consumed quantities in several two-level mixed effect models. Household members in our sample spend up to several hours each day filling storage vessels, even if a private connection to the piped network is available. Average time cost amounted to the equivalent of 4.23–13.81% of monthly household cash income. Our analyses indicate that procurement time reduces quantitative water demand in a significant way. The households incurring the highest per-unit time cost consumed water quantities below minimum levels recommended for human health. This substantiates that time costs can impede access to water and are a relevant issue for water management and policy.