A method to determine minimum contract bids for incentive highway projects
Abstract An increasing number of state highway agencies (SHAs) are using Incentive/Disincentive (I/D) bidding for highway construction. The I/D bidding concept is designed to shorten the total contract time by allowing the contractor to obtain incentives for early completion and pay disincentives for late completion of a project. Contractors are then presented with the problem of determining a better strategy to develop their bid estimate, including construction cost, construction time, and I/D. This research offers a quantifying model to determine an optimum low bid to submit for both linear I/D and escalating I/D type projects. A functional relationship between the construction cost and time duration is developed from the Florida Department of Transportation (FDOT) projects. The equation is then combined with the I/D to determine the optimum low bid price and time. Finally, several projects completed by the FDOT will be utilized to illustrate the validity of this model.
Revenue-Sharing Contract Design for Construction Onsite Equipment Sharing
Equipment sharing between contractors can relieve equipment shortages and enhance construction productivity. Previous studies focused on how to allocate cooperative gains of resource sharing among contractors, and yet how to ensure the owner and contractors form a coalition that contributes to maximizing resource-sharing gains still needs to be studied. This article examines the contract design problem of motivating the contractors and owner to willingly cooperate to increase the amount of shared equipment to an optimal level to maximize the project’s overall gain through equipment sharing. First, two trilateral equipment-sharing game models including a critical contractor, a non-critical contractor, and the owner are developed, which represent contractors’ different leadership positions in equipment sharing. Then, a set of revenue-sharing contracts are devised to compensate the contractors’ equipment-sharing cost and the owner’s extra duration reward cost by reassigning the consequently increased operation income. Eventually, a numerical study demonstrates that the proposed contracts can prompt members to make decisions according to an optimal solution to maximize the overall gains of equipment sharing, and each member’s gain and the construction duration compression are improved. This article contributes to onsite resource management by introducing a revenue-sharing contract to fairly compensate construction members’ equipment-sharing costs to achieve optimal cooperative gains.
Prediction of a representative point for rail temperature measurement by considering longitudinal deformation
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, the maximum variation of the internal rail temperature can be >7 ℃ depending on the point of measurement. However, there is as yet no sufficient information about how to predict the measurement point to represent the thermal deformation due to temperature distribution. In this study, the authors report a new point, called the representative measurement point, at which the rail temperature can be measured. This point considers the average deformation of the rail through structural analysis by adopting experimental and actual rail temperature data. The authors designed and installed a measurement system similar to an actual rail environment. Using the system, various data were acquired (internal/surface rail temperature and weather data) for 10 months. On the basis of these data, an analysis was done to calculate the average deformation point through thermal analysis. Finally, the representative measurement point was proposed as the position at which the average deformation point converges regardless of weather or seasons. The authors believe that the method described herein is advantageous in that it could be used in a high-accuracy temperature-monitoring system and for predicting thermal deformation and buckling.