Journal of Infrastructure Systems

Conserving natural resources for future generations is a common objective of sustainable design and construction. Making use of materials in an efficient manner to improve sustainability is especially applicable on roadway construction projects which can consume significant quantities of materials. An understanding of how best to eliminate material waste on roadway projects requires knowledge of the amount of material waste generated during the various phases of the roadway life cycle. This paper presents a research study undertaken to quantify the amount of materials wasted during the roadway life cycle. The study included life-cycle inventory assessments (LCI) of a continuously reinforced concrete (CRC) roadway and an asphalt concrete (AC) roadway with respect to the waste generated from extraction of raw materials through the end-of-life (EOL) of the roadways. For the CRC roadway, waste was primarily generated at the roadway EOL, accounting for approximately 53% of the total amount of waste generated over the roadway’s entire life cycle. A similar trend was observed for the AC roadway in which 59% of the total waste occurred at EOL. For both CRC and AC roadways, waste created during placement of materials is almost negligible compared to that generated during the manufacturing phase and at EOL. The results suggest that application of sustainable concepts (reduce, recover, reuse, and recycle waste) and use of recycled instead of natural materials would help create sustainable roadways.

The revenue risk is considerable in infrastructure project financing arrangements such as build–operate–transfer (BOT). A potential mitigation strategy for the revenue risk is a governmental revenue guarantee, where the government secures a minimum amount of revenue for a project. Such a guarantee is: (1) only redeemable at distinct points in time; and (2) more economical if the government limits the guarantee’s availability to the early portions of a BOT’s concession period. Hence, a guarantee characterized by this type of structure takes the form of either a Bermudan or a simple multiple-exercise real option, depending upon the number of exercise opportunities afforded. The multi-least-squares Monte Carlo technique is presented and illustrated as a promising approach to determine the fair value of this variety of real option. This method is far more flexible than prevailing approaches, so it represents an important step toward improving risk mitigation and facilitating contractual and financial negotiations in BOT projects.

A methodology is proposed for the development of decision criteria for sewer asset management. Six principles have been established and applied. (1) Criteria are developed for supporting the definition of investigation programs and rehabilitation programs. (2) Criteria are calculated from complementary performance indicators (PIs) relating to defects, dysfunctions or impacts. (3) PIs may be assessed by observation, by estimation, or by combination of other PIs. (4) PIs refer to individual assets or to subsystems. (5) Relationships between PIs can be described by qualitative models. (6) Each criterion is assessing a contribution of a dysfunction of a sewer segment to an impact. The implementation of these principles consists of four steps. (1) Setting up typologies for defects, dysfunctions and impacts. (2) Deriving indicators for defects, dysfunctions and impacts. (3) Combining dysfunction and impact indicators into decision criteria. (4) Using criteria for planning actions. The evaluation of indicators based on visual inspection results is focused on. The methodology provides a rational framework for supporting asset management in organizing all potentially available information into a comprehensive set of PIs and decision criteria.

We present a quadratic programming formulation for the problem of obtaining optimal maintenance and repair policies for multifacility transportation infrastructure systems. The proposed model provides a computationally tractable framework to support decision making, while accounting for economic interdependencies that link the facilities that comprise these systems. To demonstrate the advantages of the proposed model, we present numerical examples that capture economic interdependencies reflecting both costs associated with disruptions/loss of throughput, as well as the benefits associated with coordinating intervention schedules of adjacent facilities to reduce costs associated with resource and personnel delivery. The results illustrate situations where it is optimal to coordinate (synchronize or alternate) interventions for clusters of facilities in transportation systems.

A global network optimization model has been developed for generating a pavement repair plan using expected performance of pavement repair works. The expected performance of pavement repair works is represented by the expected age (service life) associated with potential repair actions. The expected age defines the anticipated pavement condition improvement obtained from applying a particular repair action. The expected age for each repair action is usually known from either experience or assumed as part of a design procedure. A constrained linear optimization model is formulated with its main objective of optimizing the expected pavement condition improvement. Pavement condition improvement is defined as the age gain in year lane kilometer or average age in years extended to a pavement network as a result of applying potential repair actions. The global linear model is subjected to a single budget constraint enforcing the total budget available for the entire network and limitation constraints placing lower and upper limits on the repair variables. The optimum repair plan provides a macroscopic solution as the repair variables represent pavement proportions that should be treated by the corresponding repair actions. The pavement network is divided into a number of systems with similar pavement structures and loading conditions. Presented sample results have indicated that global network optimization of the pavement management problem may not result in a rational budget allocation among deployed pavement systems. This problem can be solved by enforcing system improvement requirement constraints.

Corrosion of reinforcing steel is the main course of deterioration of reinforced concrete (RC) structures in chloride contaminated environments. Various measures can be employed to protect RC structures against corrosion and to improve their durability. Efficiency of these measures can be compared using life-cycle cost analysis. The present paper examines the influence of different sources of uncertainty associated with modeling corrosion initiation and propagation (and corresponding structural damage) on results of life-cycle cost analysis, in particular, on estimated cost of failure. Serviceability failure due excessive cracking is considered. The considered sources of uncertainty include uncertainties associated with time-dependent modeling surface chloride content and chloride diffusion coefficient, prediction of threshold chloride concentration and corrosion rate, and modeling crack initiation and propagation.

The deterioration of municipal underground infrastructure systems and a growing demand for utility services have increased the necessity for more efficient installation, inspection, repair, rehabilitation, and replacement of underground utilities. With conventional open-cut construction methods, direct costs are greatly increased by the need to restore ground surfaces such as sidewalks, pavement, landscaping, and brick paving. Furthermore, taking social and environmental factors into account, open-cut methods have adverse impacts on the community, business, and commuters due to undesirable pollution and traffic disruptions. Trenchless technologies that are used to repair, upgrade, replace, or install underground infrastructure systems with minimum surface disruption offer a viable alternative to existing open-cut methods. The objective of this paper is to describe a methodology for quantitatively assessing and comparing direct, social, and environmental costs associated with municipal underground pipeline construction. It is suggested that decision makers consider combining these costs with direct capital costs so that the best alternative is selected, which in certain cases can make trenchless technology the most economical alternative. Moreover, productivity, workers’ safety, and structural issues have shown that trenchless technology is a more efficient method for underground infrastructure systems.

Flooding and flash flooding pose serious infrastructure hazards to human populations in many parts of the world. During a flood, it is critical to identify road segments that are flooded so that rescue and response routes can be determined and rescue personnel and supplies can be distributed promptly. Presently there is not an information system that, given a specific flood level, can accurately predict flooded road segments and their depth and provide this information for rescue activities. This paper reports on a study to develop a prediction prototype to identify flooded road segments during a flood. It includes two tasks: determining flood extent and depth and identifying road segments that are flooded. Unlike a traditional approach, which determines flood extent and depth by comparing a water surface and a terrain surface, this study determines flood extent and depth using light detection and ranging data in a geographic information system. This flood extent and depth information is integrated with 3D road centerline data created in a related study. It is believed that the proposed prediction model and algorithms in this study can provide a practical and efficient approach to identify road segments that are flooded in a timely manner to help determine rescue routes. These models show promise. Additional research is required to fully validate the models.

This paper presents a traffic simulation approach to evaluating the relative benefits of transportation management strategies aimed at maximizing the utilization of road infrastructure. The approach is demonstrated using a case study of an infrastructure upgrade of a commuting corridor in Brisbane, Australia. A detailed traffic simulation model was developed for the network under consideration, and a number of different infrastructure management strategies were investigated. These included treatment of the additional road capacity as a bus lane (available for buses only), a high occupancy vehicle lane, and a general traffic lane open to all vehicles. The simulation results showed that a bus lane would produce the best travel time benefits for buses (19% decrease in travel times and 68% improvement in travel time reliability). This, however, was achieved at the expense of reduced benefits to other road users. The work reported in this paper demonstrates the feasibility of using traffic simulation to quantify the benefits of alternative infrastructure strategies based on modeling of individual vehicles and their interactions on the road network.