Khaled Nassar

Design Cost Analysis of Transportation Projects

Transportation projects are usually designed in three phases: phase I is the preliminary design report, phase II involves the preparation of the actual construction documents including plans and specifications, and phase III involves the construction inspection and contract administration of the project. The process of arriving at total design man-hours and the related design costs is often the most contentious and difficult part of phase II for both the consultant and the STA (State Transportation Agency). The main objective of this research is to model the design costs of consultant designed projects. Actual data were collected from The Illinois Department of Transportation (IDOT). Statistical modeling techniques were used to predict the design costs. The models developed in the following pages will help supplement the current methods of estimating design costs currently used by IDOT. Currently the Illinois Department of Transportation maintains a set of manuals used by the Bureau of Design and Environment for guiding engineers through the design phase for highway projects. These manuals are very comprehensive covering all facets of the design process. The models contained in this research could be implemented in the Design and Environment manuals.

NIGHTTIME CONSTRUCTION ISSUES REVISITED

An investigation into nighttime construction operations at highway maintenance and reconstruction sites is presented in this paper. This investigation, which is part of a research project sponsored by the Illinois Department of Transportation (IDOT), involved two questionnaire surveys. The first survey is concerned with state Departments of Transportation (DOTs), while the other is concerned with IDOT districts. The surveys addressed issues pertaining to the different aspects of nighttime construction work such as the current practice in nighttime operations, construction-related factors, traffic-related factors, and social, economic, and environmental factors. Research results suggest that there is agreement between the two groups on many aspects of nighttime operations, however some other aspects received conflicting opinions. Many important findings were drawn from these surveys and are summarized in this paper. The study recommends the use of a more quantitative approach in dealing with some aspects of nighttime operations. This can easily be achieved on projects with dual shifts so as to exclude the effect of other affecting factors. The study also recommends the use of a separate bidding of nighttime pay items. This may not only prevent contractors from complaining about prices, but also result in more accurate and possibly lower bids. Also, any incentives provided in nighttime contracts should more reflect the expected benefits of nighttime work, particularly the savings in road user costs.

A Practical Approach for Cost/Benefit Analysis of Early Design Decisions: Application to Architectural Daylighting

Abstract Although several methods exist for performing cost/benefit analysis in architecture, mechanical and civil engineering, etc., the use of these methods in early design phases remains limited. Realizing the importance of the decisions made early in the design process and their effect on cost performance, several research efforts have developed tools and aids to help design professionals perform early cost/benefit analyses. Examples include rules of thumb, simplified formulae, algorithms, spreadsheets and nomographs. Nomographs have been developed to help in cost/benefit analyses for various applications such as generic time-value of money analysis, mechanical equipment sizing, engineering, architectural design, etc. This paper compares and discusses the use of nomographs in relation to specialized spreadsheets as tools for practical cost/benefit analysis. The paper suggests that spreadsheets in general offer a more effective and robust analysis tool when it comes to cost/benefit analysis in the built environment fields, especially for decisions in the early stages of design. The superiority of spreadsheets to nomographs is demonstrated through a practical cost/benefit analysis application to architectural daylighting design decisions. The spreadsheet method has several advantages over the nomograph method, which are explored through an actual case study of daylight cost/benefit analysis for the Kuwait Autism Center. The comparisons can be generalized for several disciplines and domains in other parts of the world.

Design of Braced and Unbraced Cantilevered Steel False Work

AbstractThe architectural design of buildings with nontypical floors can create risky situations in which cantilevered slabs and beams are extended while the floor beneath has no cantilevered slabs on which the false work can rest. The design proposed in this paper is based on using steel cantilevered false work to support the formwork system, with no need for extending the false work along the height of the building. A closed-form solution for the temporary structure was formulated and validated using a commercial software program. A parametric study was performed using the closed-form solution to study the variations of the straining actions within the members with the changes in dimensions. The study was extended to design for the lightest member configuration of the false work for each cantilevered span. The design was extended to include the addition of a diagonal bracing member. The variations between the two designs were included in the study.