Bottom‐up estimation of material stocks and flows in Toronto's road network

Abstract

Improving resource efficiency is critical to reduce the environmental impacts of constructing and maintaining the built environment. A growing body of research has been investigating where and for what purposes construction materials are consumed in cities. Much of this existing research relies on archetypes to simplify the analysis of the large number of structures, and city-scale bottom-up material stock assessments mostly examine buildings to the exclusion of other urban structures. In this research we examine the effectiveness of pavement archetypes compared to spatially disaggregate pavement material data from a municipal pavement management database for stock estimation and find that the use of archetypes can lead to asymmetric estimation errors (i.e., variability in prediction error among materials and across the city's geography). We use Toronto's road network as a case study and estimate the stocks of concrete, asphalt, and granular materials. The stock of materials is unevenly distributed, in terms of both material type (uneven distribution of concrete vs. asphalt) and when normalized by area and population. In general, the use of archetypes tends to obscure spatial variability in material use, even across a relatively limited geographical area like Toronto and relatively consistent product like roads. We argue that the uncertainty inherent in the use of archetypes is significant and should be accounted for in bottom-up urban material flow analysis, that governments are in a unique position to provide high quality data for study, and that efforts should be made to capture, collate, and share this information more widely.

Material Stock and Embodied Greenhouse Gas Emissions of Global and Urban Road Pavement

“…This approach receives criticism because of its oversimplification and time consumption if one wants to define detailed archetypes. 14 An alternative to archetypes is to collect detailed consumption data about road construction, collect empirical data from municipal or governmental agencies, 59 or use of machine learning 14 but this requires large datasets. Therefore, the use of archetypes enables a first estimation of global material stock.…”

High-Resolution Mapping of Material Stocks in Belgian Road Infrastructure: Material Efficiency Patterns, Material Recycling Potentials, and Greenhouse Gas Emissions Reduction Opportunities

“…However, this precludes capturing locational heterogeneities in road properties (e.g., pavement structure, material type, layer thickness, and material composition) governed by traffic, climatic, and soil conditions. To date, only a few studies , have employed location-specific data to estimate materials stocked in road infrastructure, thanks to continuous documentation efforts of the cities or countries involved in these studies. However, location-specific data are scarce and not always available, calling for novel methods to capture locational heterogeneities in road properties.…”

“…Most recently, several studies have attempted to provide a granular understanding of materials stocked in road infrastructure. − Most of them use an archetype-based approach based on design standards and assumptions to determine material intensities and quantify material stocks. However, this precludes capturing locational heterogeneities in road properties (e.g., pavement structure, material type, layer thickness, and material composition) governed by traffic, climatic, and soil conditions.…”

A bottom‐up modeling of metabolism of the residential building system in China toward 2050

“…The metabolism of the building system, which includes construction, use, waste demolition, and recycling, is tied to the development of society and economy and plays a significant role in resource utilization and environmental impact in the anthroposphere. Half of the materials extracted from the lithosphere by human beings are transformed into building materials and related products (Kloostra et al., 2022). The ever‐growing construction projects have accelerated the accumulation of materials in the building system.…”