Journal of Infrastructure Systems

Wassily Leontief received the 1973 Nobel Price in Economics for developing what came to be known as the Leontief input-output model of the economy. Leontief's model enables understanding the interconnectedness among the various sectors of an economy and forecasting the effect on one segment of a change in another. A Leontief-based infrastructure input-output model is developed here to enable an accounting of the intraconnectedness within each critical infrastructure as well as the interconnectedness among them. The linear input/output model is then generalized into a generic risk model with the former as the first-order approximation. A preliminary study of the dynamics of risk of inoperability is discussed, using a Leontief-based dynamic model. Several examples are presented to illustrate the theory and its applications.

The production of equipment and materials used for transportation facilities and services can have significant environmental effects. Considerable effort is expended to reduce such effects as efficiently and effectively as possible. In this paper, we estimate external environmental costs resulting from the production of common transportation equipment, materials, and services. These external cost estimates only include the effects from air emissions of conventional pollutants, including carbon monoxide, greenhouse gases (or global warming potential), volatile organics, sulfur dioxide, particulate matter, and nitrogen oxides. The estimates include all the direct and indirect supply chain emissions, such as electricity generation and mining. The cost estimates are uncertain and are likely to be underestimates of total external costs. However, the estimates should be useful for an initial assessment of the total social costs of transportation projects, and to indicate products and processes worthy of additional pollution prevention efforts. In particular, we find that additional external environmental costs may range from as low as 1% to as high as 45% for transportation services. External environmental costs of transportation equipment manufacturing range between 0.3 and 11%, while the external environmental costs of transportation construction and operation materials are estimated to vary between 1 and 100%.

Continuous rapid economic growth in the past two decades places heavy demands on infrastructure facilities in China, which in turn provides attractive but often challenging development opportunities for foreign investors. BOT (build-operate-transfer) type project financing arrangements, such as joint venture BOT, sole proprietorship BOT, build-transfer-operate, and transfer-operate-transfer have been explored, with a number of projects successfully developed in diverse industries. Drawing examples from key landmark projects, this paper provides an overview and analysis of such developments. It provides pointers to improve procurement processes and timely insights into relevant Chinese initiatives, legal structures, foreign investment protocols, various project-financing models, tendering systems, specific procurement procedures, and particular challenges facing BOT-based approaches in China.

Interference between trees and sewer systems is likely to occur in old systems and in cracked pipes. Factors that contribute to damage include old pipes with joints, shallow pipes, small-dimension pipes, and fast-growing tree species. Because roots are reported to cause >50% of all sewer blockages, costs associated with root removal from sewers is substantial. In smaller-dimension pipes, root removal every year or every other year is common. Major resources are put into replacement and renewal of existing pipes, which is sometimes accelerated because of root intrusion. Collapse repair costs are greater than new construction, but costs associated with root removal may be one-sixth the cost of pipe replacement/renewal due to roots. Major breaks and stoppages seem to occur more frequently in older systems than in new. Therefore, it seems worthwhile to carry out preventative maintenance of the older parts of the sewer system.

Because the provision of an adequate and reliable water supply system involves a very high level of investment, it is essential that the layout and design of such systems are very carefully planned and the operation of their hydraulic infrastructures is properly managed. This paper describes a simulated annealing method that can be used to find the least-cost design for a gravitational looped water distribution network. Simulated annealing heuristics have proved to be extremely efficient in solving classic combinatorial problems such as the “traveling salesmen” problem. To assess its performance, this heuristic method has been applied to well-known networks in the literature. The results compare very favorably with those obtained by other optimization methods, confirming that simulated annealing is capable of handling nonlinear mixed-integer problems such as this. This encourages further research in this area.