Search

Compressing project schedule using activity accelerating and overlapping requires that an intensive time-cost trade-off analysis be carried out, to determine costs and benefits for each day of compression. However, the cost elements and implications of compression techniques differ significantly, since activity accelerating imposes extra direct cost whereas activity overlapping adds a risk of changes and rework. Such a trade-off becomes even more complicated in capital projects comprised of a large number of schedule activities and relationships. The variety of combinations of accelerating and overlapping of different activities in these complex networks can offer numerous possibilities for compression with various costs and potential risks. The lack of a reliable analytical tool for performing a precise cost-benefit analysis causes this critical task to be performed in a subjective manner during the planning stage of projects. The purpose of this paper is to present an advanced method using a multi-objective evolutionary optimization tool seeking the optimum degree of accelerating and overlapping during the schedule compression process. This optimization technique would be beneficial in maximizing project benefits while meeting the intended target dates. Key words: schedule compression, crashing, overlapping, substitution, accelerating, optimization, genetic algorithms. Raccourcir un echeancier de projet par l'acceleration et le chevauchement des activites demande une analyse circonstanciee comparative temps-couts approfondie afin de determiner les couts et les avantages pour chaque jour de compression. Toutefois, les elements de couts et les implications des techniques de compression different beaucoup, puisque l'acceleration des activites exige des couts directs supplementaires alors que le chevauchement des activites ajoute un risque de changements et de reprise du travail. Un tel compromis devient encore plus complique dans les projets d'immobilisations comportant un grand nombre d'activites programmees et de relations. La variete de combinaisons d'acceleration et de chevauchement des differentes activites dans ces reseaux complexes permet d'offrir plusieurs possibilites de compression presentant divers couts et risques potentiels. Le manque d'outils analytiques fiables pour realiser une analyse couts-avantages precise fait que cette tache doit etre realisee subjectivement durant l'etape de planification des projets. Le but de cet article est de presenter une methode evoluee utilisant un outil d'optimisation evolutionnaire a objectifs multiples recherchant le niveau optimal d'acceleration et de chevauchement durant le processus de compression de l'echeancier. Cette technique d'optimisation pourrait permettre de maximiser les avantages d'un projet tout en rencontrant les dates ciblees indiquees. [Traduit par la Redaction] Mots-cles: compression de l'echeancier, compression des delais, chevauchement, substitution, acceleration, optimisation, algorithmes genetiques., Introduction Schedule compression is the technique by which project managers shorten project duration. Generally, schedule compression is performed using two main techniques. The first may be termed 'accelerating'. Accelerating is [...]

Schedule compression is an attempt to reduce project durations for early delivery, or to catch up on occurred delays. This is usually performed using 'crashing', 'overlapping' and 'substitution' of activities. 'Crashing' is shortening task duration by adding more resource hours. 'Substitution' is changing the method or tool by which the activity is performed. 'Overlapping' is performing sequential activities in parallel. Few studies can be found in the literature that compare costs and benefits of each technique and recommend the optimum combination of these techniques in project schedules. In fact, the implications of each technique are inherently different since crashing and substitution impose extra cost whereas overlapping adds the risk of changes and rework. Therefore, it is a challenge to develop a reliable analytical tool for performing time-cost trade- offs using the three methods. There are also few studies in the literature to propose a practical method for performing schedule compression by combining these techniques. The purpose of this paper is to discuss these schedule compression techniques in detail, and present and validate a heuristic method to perform the combination of crashing, overlapping and substitution in a project schedule, to reach the maximum benefit while meeting the project target dates. Key words: schedule compression, acceleration, overlapping, crashing., Resume: La compression de l'echeancier est une tentative de reduire la duree des projets pour permettre une livraison precoce ou pour rattraper les delais encourus. Cela est normalement realise en [...]

To improve construction productivity and performance, it must be measured. The Construction Sector Council (CSC) has started a Labour Productivity and Project Performance Benchmarking Program for the infrastructure sector of the construction industry in Canada. Metrics were developed for project cost, time, safety, and quality performance; labour productivity; rework; project conditions; and management practices related to health and safety. Data from 19 projects located in different regions of Canada were collected and analyzed. Based on the results and on industry feedback, additional metrics for practices related to project planning, materials management, and construction supervisory skills development were developed. This paper describes the development of the program. Lessons learned during the development and implementation of the benchmarking and metrics program are summarized and steps to establish a sustainable program are identified. It is concluded that a successful program is feasible and has the potential to have broad impact. Key words: benchmarking, metrics, project performance, labour productivity, construction industry, management practices. La productivite et le rendement en construction doivent etre mesures si l'on veut les ameliorer. Le Conseil sectoriel de la construction (CSC) a lance un programme d'analyse comparative de la productivite de la main-d'oeuvre et de rendement de projets pour le secteur des infrastructures de l'industrie de la construction au Canada. Des parametres ont ete developpes pour le cout du projet, le temps, la securite et le rendement en qualite, ainsi que la productivite de la main-d'oeuvre, la reprise de travaux, les conditions du projet et les pratiques de gestions associees a la sante et la securite. Les donnees provenant de 19 projets situes dans differentes regions du Canada ont ete analysees. En se basant sur les resultats et la retroaction de l'industrie, des parametres additionnels sur les pratiques associees a la planification de projets, la gestion des materiaux et le developpement d'habiletes de supervision en construction ont ete integres. Le present article decrit le developpement du programme. Les lecons apprises durant le developpement et l'implantation du programme d'analyse comparative et des parametres sont resumees et les etapes visant a etablir un programme durable sont identifiees. Il est donc possible d'avoir un bon programme qui peut avoir un impact majeur. Mots-cles : analyse comparative, parametres, rendement du projet, productivite de la main-d'oeuvre, industrie de la construction, pratiques de gestion. [Traduit par la Redaction], Introduction Construction productivity directly affects the price of construction projects. A poor national productivity in construction impacts negatively the robustness of its economy: it affects the outcomes of the national [...]

A skill-measuring criterion or strategy can be used to optimize the scarce skilled labour force in the Canadian construction industry. The University of Calgary conducted an extensive study to assess the skill levels and team performance of field workers and managers in Alberta's building construction projects. Over 150 workers and field managers were interviewed, surveyed with questionnaires and observed, to identify team efficiencies, skill levels, team spirit, and team perceptions of supervision. The average construction worker had over 15 years of field experience. Most of the workers were high school educated. More than 70% of the workers wanted to improve their career skills; however, internal and external opportunities were limited and (or) not promoted by the respective construction companies. A very few foremen had certified skills in administration, computer handling, planning, job management and work records. The research clearly noted the urgent need for training programs, for workers and field managers, to improve their present skill levels. Key words: worker skills, supervisory skills, construction productivity, team spirit, worker education. Un critere / une strategie de mesure des competences peut etre utilise pour optimiser la main-d'oeuvre experimentee, rare dans l'industrie canadienne de la construction. L'Universite de Calgary a realise une vaste etude pour evaluer les niveaux de competences et le rendement des equipes de travailleurs et de chefs de chantier dans les projets de construction de batiments en Alberta. Plus de 150 travailleurs et chefs de chantier ont ete interviewes, ont rempli des questionnaires et ont ete observes afin d'identifier les efficacites des equipes, les niveaux de competences, l'esprit d'equipe ainsi que les perceptions que les equipes avaient de la supervision. Le travailleur de la construction moyen possede plus de 15 ans d'experience sur le terrain. La plupart des travailleurs detiennent un diplome d'etudes secondaires. Plus de 70 % des travailleurs veulent ameliorer leurs competences. Toutefois, les occasions a l'interne et a l'externe sont limitees et (ou) non publicisees par les compagnies de construction. Tres peu de contremaitres possedent des competences certifiees en administration, en informatique, en planification, ainsi qu'en gestion des travaux et de registres de travail. La recherche note clairement le besoin urgent d'avoir des programmes de formation pour les travailleurs et les chefs de chantier afin d'ameliorer leur niveau actuel de competences. Mots-cles : competences des travailleurs, competences de supervision, productivite en construction, esprit d'equipe, education des travailleurs. [Traduit par la Redaction], 1. Introduction Human skills are essential in achieving successful execution of a construction project with effective communication, motivation, leadership, teamwork, and mutual trust. These skills play a major role not [...]

This paper explores factors that contribute to claims of changed soil conditions in infrastructure and building projects through a limited review of Canadian legal cases. Forty-one cases, relating to geotechnical problems covering a period of 25 years (1982-2006), were studied. The information obtained was categorized according to the causes for geotechnical claims. The most frequent causes of geotechnical disputes were found to be different soil conditions and recommendations than expected from those given in the geotechnical report, inaccuracies in the design plans and specifications, and the owner's failure to disclose important information. The paper also discusses the special requirements for preparing geotechnical information for construction and suggests precautionary measures to reduce the number of disputes or to arrive at an equitable resolution. These measures require more proactive planning and may require additional funds before the bidding stage to perform a more detailed soil investigation, keep communication clear among all participants, and make a greater effort to provide accurate designs and specifications. Key words: Canadian legal cases, differing soil condition, dispute resolution, geotechnical claims. Cet article explore les facteurs qui ont contribuee aux plaintes reliees aux changements des conditions des sols pour des infrastructures et projets de construction, et ce a partir d'une revue sommaire de cas leegaux canadiens. Quarante-et-un cas associesa des problemes geotechniques couvrant une periode de 25 ans (1982 a 2006) ont ete etudies. L'information obtenue a ete; classeee selon les causes des plaintes geotechniques. Les causes les plus frequentes de disputes geotechniques sont les conditions des sols et les recommandations diffeerentes de celles notees dans les rapports geotechniques, des erreurs dans les plans de conception et dans les specifications, et l'omission du proprieetaire de devoiler des informations importantes. L'article discute aussi des particularitees dans la preparation d'un rapport geotechnique pour la construction, et suggeere des mesures preventives afin de reduire le nombre de conflits ou de les resoudre de facon equitable. Ces mesures neecessitent une planification proactive et peuvent demander du financement additionnel avant l'etape de soumission pour effectuer une investigation du sol plus detaillee, pour conserver une bonne communication entre toutes les parties, et finalement pour fournir un effort plus grand afin d'offrir des conceptions et specifications precises. Mots-cles: cas leegaux canadiens, diffeerentes conditions des sols, resolution de conflits, plaintes geotechniques. [Traduit par la Redaction], Introduction A 'differing soil condition' or 'changed soil condition' is a condition encountered when a subsurface stratum is materially different from what is given in the contract documents and specifications [...]

A recent study on construction productivity improvement at the University of Calgary revealed the direct tool time (working time) of Alberta's commercial construction to be about 51%. This study exposed inadequate communication and unavailability of required information as the main causes for a relatively lower tool time. Use of information technology (IT) to overcome widely visible communication issues was extremely limited at the construction site level. Construction companies' hesitation to adopt new technologies was well noted whereas construction workers expressed their willingness and ability to use IT at the site level. The objective of this paper is to discuss the concept and the application of a novel communication tool (called an information booth) developed and pilot tested at a construction project. The concept and the technology presented in this paper have been tested at an actual construction project resulting in improvements in construction productivity, worker satisfaction, and efficiency. This paper also elaborates the rationale for a new technological framework (and the information booth), barriers for technology implementation, research objectives, methodology, and data analysis. Key words: information technology, construction productivity, worker satisfaction, human-technology interaction, on-site communication. Une recente etude sur 1'amelioration de la productivite dans le domaine de la construction menee a l'Universite de Calgary a revele le temps d'utilisation directe des outils (temps de travail) dans le domaine de la construction commerciale en Alberta; il etait d'environ 51 %. Cette etude a determine que les principales causes du temps de travail reel relativement faible sont une communication inadequate et la non-disponibilite de l'information requise. L'utilisation des technologies de l'information (TI) pour surmonter les problemes de communication bien evidents etait extremement limitee sur les sites de construction. L'hesitation des compagnies de construction a adopter les nouvelles technologies a ete bien notee alors que les travailleurs de la construction ont exprime leur volonte et leur capacite a utiliser les TI sur le site. Cet article discute du concept et de l'utilisation d'un nouvel outil de communication (appele << kiosque d'information >>) developpe et teste a l'echelle pilote sur un site de construction. Le concept et la technologie presentes dans cet article ont ete mis a l'epreuve sur un reel projet de construction; il en a decoule des ameliorations en productivite en construction, en satisfaction des travailleurs et en efficacite. Cet article traite egalement de la justification d'un nouveau cadre technologique (et du << kiosque d'information >>), des obstacles a l'implantation de la technologie, des objectifs de recherche, de la methodologie ainsi que de l'analyse des donnees. Mots-cles : technologies de l'information, productivite en construction, satisfaction des travailleurs, interaction humaintechnologie, communication sur le site. [Traduit par la Redaction], Background The construction industry faces many challenges at the beginning of the 21st century as it is forced to change and to incorporate new advanced technologies into the construction process [...]

Measuring projects' cost and schedule risks in an integrated framework using simulation has several modeling challenges that have yet to be addressed by researchers. This paper presents a multilevel network modeling approach that aims to integrate a combination of different networks in one framework, and presents a computer simulation implementation to the cost and time risk assessment network (CTAN). The CTAN is an integrated network that includes uncertainties in the realization of the schedule logic, in activities durations, in project scope, and in cost. The simulation model is a decision support simulation system (DSSS) that currently consists of three modules: the CTAN, the stochastic decision trees, and the stochastic shortest/longest rout network. The CTAN-DSSS may be used in cost and schedule risk assessment. It completely integrates with other DSSS networks and deals with risks associated with cost, time, and scope at equal importance. The DSSS was verified by conducting several tests and validated by its extensive use for both undergraduate and graduate courses in Civil Engineering at the University of Calgary over the last three years. DOI: 10.1061/(ASCE)0733-9364(2007)133:1(96) CE Database subject headings: Computer analysis; Cost control; Risk management; Critical path method; Project management; Network analysis; Quantitative analysis; Stochastic processes.

Decision trees (DTs) have proven to be valuable tools for decision making. The common approach for using DTs is calculating the expected value (EV) based on single-number estimates, but the single-number EV method has limited the DTs' real-life applications to a narrow scope of decision problems. This paper introduces the stochastic multilevel decision tree (MLDT) modeling approach, which is useful for analyzing decision problems characterized by uncertainty and complexity. The MLDT's advantages are shown through a computer simulation program: the Decision Support Simulation System (DSSS). The DSSS allows users to model probabilistic linear graph networks and provides a hierarchical modeling method for modeling decision trees to present uncertainties more accurately. It consists of three modules: tree analysis networks (TANs), the shortest and longest path dynamic programming analysis network, and cost time analysis networks. The paper only discusses the TAN module by presenting the MLDT concept under the TAN of the DSSS computer application. The content of the paper includes the modeling approach, its advantages, and examples that can be used in modeling stochastic trees. The DT-DSSS was verified by conducting several tests and validated by using it extensively for undergraduate courses in civil engineering at the University of Calgary for the last two academic years. CE Database subject headings: Decision making; Models; Stochastic models; Networks; Construction industry.

Abstract: Construction site operations are very complex, and they involve complicated relationships among numerous tasks, factors, obstacles, risks, and uncertainties, or triggering situations that affect productivity. To improve the performance [...]

This paper describes the organization and conduct of a 4th year capstone project for civil engineering students at the University of Calgary that embodied a very significant international component and the difficulties inherent to that component. The project design education process results in numerous contributions to university, industry, and society by permitting students to develop innovative design solutions that reflect multicultural influences, while also recognizing that Civil Engineering design is universal. This paper explains the novel approach adopted for the final-year civil engineering design course in 2002-2003 using the largest urban renewal project currently underway in Europe, for which the students had the opportunity to develop designs. The concept, structure, challenges, and contributions as well as the successful outcome of the civil engineering design course are also explained in the paper. Overall, this design project provided the students with valuable experience in communication, design, professional practice, and organizational skills that will be useful in their future careers, in addition to the challenges of dealing with a real and international client of a complex project. DOI: 10.1061/(ASCE)1052-3928(2006)132:4(297) CE Database subject headings: Undergraduate study; Engineering education; Project management; International factors; Foreign projects.

Abstract: For decades, many researchers have reported the decline in construction productivity, but it is impossible to generalize the productivity problems due to issues such as geographical differences, weather changes, [...]

This is an excellent discussion of our paper. We thank the author for providing the background that we were not privy to. His list of lessons learned provides excellent and [...]