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.

Transportation greenhouse gas (GHG) emissions often account for the largest share of urban GHG emissions. Consequently, large-scale reductions in urban GHG emissions will not be possible without significant improvements in the transport sector. Increasing public transit mode share is widely promoted in efforts to reduce GHG emissions from transport. Large increases in public transit use will require the provision of new transportation infrastructure, which is itself GHG intensive. This paper presents a time-dependent analysis of the embodied GHG emissions associated with construction and reconstruction for the refurbishment and street redesign of the 510 Spadina streetcar route in Toronto, Canada during a 38-year period. From 1987 to 2015, the embodied emissions in the line's civil infrastructure are calculated as 27.4 kilotons of CO 2 equivalent (ktCO 2 e). It is expected that, by 2025, further reconstruction of the right-of-way (ROW) will increase embodied GHG emissions to 32.1 ktCO 2 e. Overall, reconstruction projects increase GHG emissions by 25.9% beyond initial construction. When accounting only for at-grade infrastructure, reconstruction increases embodied emissions by 45.8% during the 38-year study period.