SCUBA Diver Specialization and Behavior Norms at Coral Reefs

SCUBA diving is an increasingly popular activity that provides a number of benefits to coastal communities. However, the sustainability of recreational diving on coral reefs is largely dependent on the health of reef ecosystems. Divers can minimize their impacts to coral reefs through responsible diving behaviors, which are in part guided by social norms. The behavioral obligation and sanction components of twelve diving behaviors were determined for Florida Keys divers throughout the course of a year. Recognizing that recreationists are not homogenous, these norms were compared according to diver specialization level. Specialized divers felt a stronger obligation not to touch corals and to pick up garbage from the sea floor than did less specialized divers. Specialized divers also reported they would feel greater embarrassment for losing buoyancy control, touching corals, taking pieces of dead corals, or touching marine mammals. The findings point to a connection between specialization level and social norms, and a relationship to ensuring continued reef health.     

Long-memory characteristics of urban roadside air quality

Carbon monoxide is a major contributor to air pollution in urban cities, particularly at the roadside. Hourly, monthly and seasonal mean carbon monoxide concentration data are collected from a roadside air monitoring station in Hong Kong over 7-years. The station is a few metres from a major intersection surrounded by tall buildings. In particular, hourly patterns of concentrations on different days of the week are investigated. The data show that hourly carbon monoxide concentrations resemble the traffic pattern of the area and tend to be lower in the summer. Using a seasonal autoregressive integrated moving average models shows that the daily traffic cycle strongly influences concentrations. Further, it is found that urban roadside carbon monoxide monitoring data exhibits a long-memory process, suggesting that a model incorporating long memory and seasonality effects is needed simulate urban roadside air quality.     

Partition‐based algorithm for estimating transportation network reliability with dependent link failures

Evaluating the reliability of a transportation network often involves an intensive simulation exercise to randomly generate and evaluate different possible network states. This paper proposes an algorithm to approximate the network reliability which minimizes the use of such simulation procedure. The algorithm will dissect and classify the network states into reliable, unreliable, and un‐determined partitions. By postulating the monotone property of the reliability function, each reliable and/or unreliable state can be used to determine a number of other reliable and/or unreliable states without evaluating all of them with an equilibrium assignment procedure. The paper also proposes the cause‐based failure framework for representing dependent link degradation probabilities. The algorithm and framework proposed are tested with a medium size test network to illustrate the performance of the algorithm.     

车辆安全和联合国十年行动计划

预计到2030年道路交通事故将成为第五大致命原因，每年死亡人数将上升至240万人。儿童、青少年和自行车、摩托车车手以及行人这类易受碰撞的群体是最处于危险之中的。     

A method to assess demand growth vulnerability of travel times on road network links

Many national governments around the world have turned their recent focus to monitoring the actual reliability of their road networks. In parallel there have been major research efforts aimed at developing modelling approaches for predicting the potential vulnerability of such networks, and in forecasting the future impact of any mitigating actions. In practice—whether monitoring the past or planning for the future—a confounding factor may arise, namely the potential for systematic growth in demand over a period of years. As this growth occurs the networks will operate in a regime closer to capacity, in which they are more sensitive to any variation in flow or capacity. Such growth will be partially an explanation for trends observed in historic data, and it will have an impact in forecasting too, where we can interpret this as implying that the networks are vulnerable to demand growth. This fact is not reflected in current vulnerability methods which focus almost exclusively on vulnerability to loss in capacity. In the paper, a simple, moment-based method is developed to separate out this effect of demand growth on the distribution of travel times on a network link, the aim being to develop a simple, tractable, analytic method for medium-term planning applications. Thus the impact of demand growth on the mean, variance and skewness in travel times may be isolated. For given critical changes in these summary measures, we are thus able to identify what (location-specific) level of demand growth would cause these critical values to be exceeded, and this level is referred to as Demand Growth Reliability Vulnerability (DGRV). Computing the DGRV index for each link of a network also allows the planner to identify the most vulnerable locations, in terms of their ability to accommodate growth in demand. Numerical examples are used to illustrate the principles and computation of the DGRV measure.     

Formulating and solving the network design problem by decomposition

The optimal transportation network design problem is formulated as a convex nonlinear programming problem and a solution method based on standard traffic assignment algorithms is presented. The technique can deal with network improvements which introduce new links, which increase the capacity of existing links, or which decrease the free-flow (uncongested) travel time on existing links (with or without simultaneously increasing link capacity). Preliminary computational experience with the method demonstrates that it is capable of solving very large problems with reasonable amounts of computer time.     

Impact of coastal construction on coral reefs in the U.S.‐affiliated pacific Islands

Abstract

During the past century, traditional ownership, control, and use of coral reef habitats in the U.S.‐affiliated islands in the Pacific have declined, exposing them to increased construction for plantation, transportation, military, urban, aquaculture, fisheries, mineral, and resort development. Dredging, filling, and other construction in coral reef and related ecosystems are expected to continue at high levels. Collectively, these activities have resulted in major adverse ecological impacts, many of which can be avoided or reduced to minor levels. Improvements in the design, siting, and construction of coastal projects can be accomplished by early integration of environmental objectives. Ecological baseline surveys; environmental impact assessments; regulatory conditions; guidelines and standards during construction; monitoring of construction; post‐construction evaluation; and long‐range research, planning, and management are among the most useful of the environmental tools to describe reefs and to identify measures to reduce or avoid adverse impacts on coral reefs.     

Book reviews

THE U.S. AIRFREIGHT INDUSTRY, by Nawal K. Taneja. Lexington Books, Lexington, Mass., 1979. 244 pp.

TRAFFIC, OPERATIONAL RESEARCH, FUTUROLOGY, by Arne Jensen. North Holland Publishing Company, Amsterdam, 1980. 321 pp. ($39.00)

PROBLEMS OF THE CARLESS, by R. E. Paaswell and W. W. Recker. Praeger Publishers, New York, 1978. 190 pp.

TRANSPORTATION AND THE ELDERLY, by Martin Wachs. University of California Press, Berkeley, 1980.

PUBLIC TRANSPORTATION: PLANNING, OPERATIONS AND MANAGEMENT, edited by George E. Gray and Lester A Hoel. Prentice Hall, Englewood Cliffs, New Jersey, 1979. 749 pp.

ETHYL ALCOHOL PRODUCTION AND USE AS A MOTOR FUEL, edited by J. K. Paul. Noyes Data Corporation, New Jersy, 1979. 354 pp ($48.00).

URBAN PLANNING AND PUBLIC TRANSPORT, edited by Roy Cresswell. The Construction Press, London, 1980. 172 pp. (£15.00)