Using Exploratory Scenarios in Planning Practice

Abstract

Problem, research strategy, and findings: Despite growing interest by practitioners in using exploratory scenarios within urban planning practice, there are few detailed guidelines for how to do this. Through the discussion of five case examples, we illustrate different approaches to linking exploratory scenarios to different planning contexts. We conclude by observing that to directly inform a plan, regardless of the specific approach taken, exploratory scenarios in urban planning must incorporate stakeholder values and not only rely on expert judgment and analysis.

Takeaway for practice: Exploratory scenarios are effective for analyzing uncertainty within a planning process. However, exploratory scenarios can be incorporated into planning practice in different ways, ranging from workshops among experts that aim to cultivate general learning to complex projects that result in highly detailed scenarios and recommendations for plans. Practitioners can draw on the cases we present to inspire planning methods for particular projects, taking into account specific contexts and goals.     

Interventions targeting non-symptomatic cases can be important to prevent local outbreaks: SARS-CoV-2 as a case study

During infectious disease epidemics, an important question is whether cases travelling to new locations will trigger local outbreaks. The risk of this occurring depends on the transmissibility of the pathogen, the susceptibility of the host population and, crucially, the effectiveness of surveillance in detecting cases and preventing onward spread. For many pathogens, transmission from pre-symptomatic and/or asymptomatic (together referred to as non-symptomatic) infectious hosts can occur, making effective surveillance challenging. Here, by using SARS-CoV-2 as a case study, we show how the risk of local outbreaks can be assessed when non-symptomatic transmission can occur. We construct a branching process model that includes non-symptomatic transmission and explore the effects of interventions targeting non-symptomatic or symptomatic hosts when surveillance resources are limited. We consider whether the greatest reductions in local outbreak risks are achieved by increasing surveillance and control targeting non-symptomatic or symptomatic cases, or a combination of both. We find that seeking to increase surveillance of symptomatic hosts alone is typically not the optimal strategy for reducing outbreak risks. Adopting a strategy that combines an enhancement of surveillance of symptomatic cases with efforts to find and isolate non-symptomatic infected hosts leads to the largest reduction in the probability that imported cases will initiate a local outbreak.     

Learning Elastic Constitutive Material and Damping Models

Commonly used linear and nonlinear constitutive material models in deformation simulation contain many simplifications and only cover a tiny part of possible material behavior. In this work we propose a framework for learning customized models of deformable materials from example surface trajectories. The key idea is to iteratively improve a correction to a nominal model of the elastic and damping properties of the object, which allows new forward simulations with the learned correction to more accurately predict the behavior of a given soft object. Space-time optimization is employed to identify gentle control forces with which we extract necessary data for model inference and to finally encapsulate the material correction into a compact parametric form. Furthermore, a patch based position constraint is proposed to tackle the challenge of handling incomplete and noisy observations arising in real-world examples. We demonstrate the effectiveness of our method with a set of synthetic examples, as well with data captured from real world homogeneous elastic objects.     

Book reviews

The Annals of Regional Science -     

Dispersion of PCB in the environment following an atmospheric release caused by a fire

During a fire at a power plant located in the coastal plain of Israel, PCBs were released to the atmosphere from a ruptured transformer. Since PCBs are probably carcinogenic to humans, this study was performed in order to assess the environmental contamination by PCBs via the atmospheric pathway and the need for remediation measures. The release conditions and the meteorological conditions which prevailed during the fire were analyzed. This provided the input to a Gaussian dispersion model used to estimate the downwind-contaminated sector as well as the location of the maximal concentration within this sector. A sampling plan was then devised and vegetation collected within this sector was analyzed for PCBs. A methodology was developed to convert PCB concentrations in vegetation to concentrations in the atmosphere. It allowed a reconstitution of the PCB source term to the atmosphere from the vegetation measurements. The PCB concentrations were found to be lower than the USEPA decontamination standards. Remediation measures were not needed beyond the plant fence.     

THE IMPLICATIONS OF ENERGY AND OTHER INPUT USE FOR CONSERVATION TILLAGE

An important issue with regard to the overall effectiveness of conservation tillage practices in reducing the impact of agricultural production on the environment concerns what happens to energy, pesticide and fertilizer use as these practices are more extensively adopted. To gain some insight into this, the conservation tillage adoption decision is modelled. Starting with the assumption that the conservation tillage adoption decision is a two step procedure — the first is the decision whether or not to adopt a conservation tillage production system and the second is the decision on the extent to which conservation tillage should be used — appropriate models of the Cragg and Heckman (dominance) type are estimated. Based on farm-level data on corn production in the United States for 1987, the profile of a farm on which conservation tillage was adopted is that the cropland had above average slope and experienced above average rainfall, the farm was a cash grain enterprise, and had an above average expenditure on pesticides, a below average expenditure on energy and a below average expenditure on custom pesticide applications. Additionally, for a farm adopting a no-tillage production practice, an above average expenditure was made on fertilizer. © 1997 by John Wiley and Sons, Ltd., Int. J. Energy Res., vol. 21, 429–446 (1997)     

The impact of the proposed reduction in the motor fuels excise tax in the United States

The analysis in this paper examines the impact of reducing the excise tax on gasoline and diesel fuel on the United States economy. The analytical approach used in the analysis consists of a computable general equilibrium model composed of fourteen producing sectors, fourteen consuming sectors, six household categories classified by income and a government. The effects of a 4·3 cents per gallon reduction in the excise tax on gasoline and diesel fuel on prices and quantities are examined. The results suggest, for example, a decrease in the tax would result in higher output by the producing sectors (by about $2·86 billion), a expansion in the consumption of goods and services (by about $3·48 billion), and an increase in welfare (by about $3·59 billion). The government would realize a decrease in revenue of about $2·37 billion. When subjected to a sensitivity analysis, the results are reasonably robust with regard to the assumption of the values of the substitution elasticities. © 1997 John Wiley & Sons, Ltd.