Viewpoint: Turning streets into housing

I argue that wide residential streets in US cities are both a contributor to homelessness and a potential strategy to provide more affordable housing. In residential neighborhoods, subdivision ordinances typically set binding standards for street width, far in excess of what is economically optimal or what private developers and residents would likely prefer. These street width standards are one contributor to high housing costs and supply restrictions, which exacerbate the housing affordability crisis in high-cost cities. Planning for autonomous vehicles highlights the overprovision of streets in urban areas. Because they can evade municipal anti-camping restrictions that restrict the use of streets by unhoused people, autonomous camper vans have the ability to blur the distinction between land for housing and land for streets. I propose two strategies through which excess street space can accommodate housing in a formalized way. First, cities could permit camper van parking on the right-of-way, analogous to liveaboard canal boats that provide housing options in some UK cities. Second, extending private residential lots into the right-of-way would create space for front-yard accessory dwelling units.

Evaluation of Walking Comfort in Children’s School Travel at Street Scale: A Case Study in Tianjin (China)

(1) Background: school travel is an important part of a child’s daily activities. A comfortable walking environment can encourage children to walk to school. The existing methods of evaluating walking environments are not specific to children’s walks to school. (2) Methods: this study proposes a method of evaluating walking comfort in children traveling to school at street scale. Related indexes were selected that reflect children’s school travel behavior and their needs in street environments based on walking environment audit tools. Factor analysis was then used to calculate the relative weight of each index. (3) Results: the new evaluation method was tested in the neighborhoods around the First Central Primary School in Hedong District, Tianjin, China. The walking comfort for children’s school travel was evaluated in eight indexes: effective street width; street flatness; street cleanliness; interface diversity; buffer; shade coverage; green looking ratio; and sound decibels. Different classes and types of streets were found to have various vulnerabilities. (4) Conclusions: this evaluation method can accurately locate the weak spots in streets to improve the local policymakers’ perception of street environments, which can greatly facilitate the implementation of precise measures to promote children walking to school.

Influence of canyon aspect ratio on microclimatic conditions: case of Lodz, Poland

This study presents an analysis of the effect of height/width proportions of street canyons on microclimatic conditions in the most urbanized part of Lodz. The empirical research covered public spaces located in the so-called Greater City Zone of Lodz, which were included in the revitalization process. In this case, two street canyons were selected, which are used as pedestrian and driving canyons (the so-called woonerfs). At first, the authors determined the average weather conditions prevailing in the warm period of Typical Meteorological Year in the area of city. On their basis, microclimatic parameters prevailing in the areas of selected street canyons were evaluated with the use of computer simulations. The next stage included the determination of aspect ratio (AR) defining the ratio of building height forming the frontage of canyons to the street width. Finally, the relation between the determined coefficient and selected weather parameters was studied.

A Method for the Assessment of the Inhalation Dose Exposure to Radionuclides in an Indoor Environment

The radionuclides released from NPPs (Nuclear Power Plants) as a result of accidents will significantly affect human health by causing cancer, genetic diseases, or acute radiation sickness. To investigate and evaluate the influence of the airborne hazardous materials on human bodies in an indoor environment in urban areas near NPPs, it is necessary to calculate the inhalation dose. In this study, a method for the assessment of the inhalation dose of indoor radionuclides was proposed. This method consists of the combination of the basic equation of natural ventilation and the empirical equation for calculation of the inhalation dose. The method was applied in a modeled densely urban domain, and CFD simulations were conducted to obtain the wind pressure distribution on the building surfaces. Moreover, the impacts of certain important parameters, including the ventilation coefficient, the age group of humans, the wind velocity, the urban street width, and the building height, were discussed in this paper. The results show that all of these parameters affect the indoor inhalation dose. In most cases, the indoor dose obtained at the same floor was higher with a higher ventilation coefficient, breathing rate, wind velocity, and street width or a lower building height. Furthermore, people living in the middle floors will generally be exposed to a lower inhalation dose than those in other floors especially the top floor.

Ablation Free Dicing of 4H-SiC Wafers with Feed Rates up to 200 mm/s by Using Thermal Laser Separation

ABSTRACTThis paper presents Thermal Laser Separation (TLS) as a novel dicing technology for silicon carbide (SiC) wafers. Results of this work will play an important role in improving the SiC dicing process regarding throughput and edge quality. TLS process parameters were developed for separating 4H-SiC wafers. Separated SiC dies were analyzed and compared with results produced with current state of the art blade dicing technology. For the first time, fully processed 100 mm 4H-SiC wafers with a thickness of 450 μm, including epi-layer and back side metal layers, could be separated with feed rates up to 200 mm/s. Besides the vastly improved dicing speed, the TLS separation process results in two important features of the separated SiC devices: First, edges are free of chipping and therefore of higher quality than the edges produced by blade dicing. Second, the TLS process is kerf free, which allows for reducing the necessary dicing street width and hence increasing the number of devices per wafer.