The impact of off-site construction transport on air quality

Today Nicolas Brusselaers (VU Brussels) promoted his thesis about the impact of off-site construction transport on air quality. The effects of air pollution are responsible for more than 364.200 premature deaths in Europe each year. Most urban areas still exceed the NOx and PM WHO air quality guidelines, of which a large share of pollutants is attributable to freight transport. The construction sector is no exception, as it relies on off-site logistics activities, i.e., transports to and from sites.

Although construction works lead to an urban economic uptake in the long run, the environmental nuisances from construction logistic (CL) activities during the works have so far been overlooked. This thesis focuses on the air quality impact of off-site construction transport, covering four main parts.

Data about construction transport

First, as there is a lack of knowledge within cities on how to set construction transport demands and how to involve actors in these processes, a stakeholder framework is presented. Next, he identified the available and required transport data (and digitization possibilities) to assess the sector’s environmental impact, such as On-Board Units.

Impact assessment

Secondly, impact assessments were conducted across various construction supply chain implementations on a single-site, city-wide, and national level. Hence, a methodological approach is proposed to derive construction-related vehicles from Heavy-Goods Vehicle (HGV) traffic based on algorithmic and geospatial analyses.

Results indicate that construction transport represents 26% of total HGV traffic in the Brussels-Capital Region (BCR), generating €45,631.85 of external costs per workday and 18% in Belgium (or €1.45 Mio per day). Subsequently, the framework was deployed to assess the transport performance of the multimodal Brussels Construction Consolidation Centre. This setup can mitigate external costs by up to 59% compared to business-as-usual operations, most notably on congestion and climate change costs.

Improvements are necessary to tackle local emissions attributable to less performant -yet ubiquitous- vessel engines. Air pollution damage costs remain high on city-level analyses, with CL inflicting €55,123.07 per
month in the BCR. A fortiori, with the growing concern on urban air quality, raises the question of where, when and by whom the most exposure costs are inflicted. So far, the geo-temporal link between the emitting freight vehicle and its receptor densities has been considered static.

A dynamic impact-pathway approach

The third part of the research introduces a dynamic impact-pathway approach, highlighting that PM & NO2 source impacts engender €61.604 of health costs in the BCR each day. Furthermore, large differences were found on the local level compared to the traditional static approach, indicating that the proposed dynamic methodology should be used for micro-scale analyses (on link, building, or neighborhood level).

Striking is that vulnerable population segments such as toddlers, school children, and the elderly, who are more sensitive to the effects of air pollution, incur 60.28% of the total health costs. However, these segments represent only a quarter of the BCR population. Moreover, a substantial overlap was found between the receptor’s presence (particularly children) and peak freight traffic movements.

The fourth part investigates the exposure effects of off-site construction transport flows spatiotemporally rerouted around air pollution hotspots. Although increased emissions are observed due to higher traveled distances and slower driving speeds, results show that the inflicted health costs can be mitigated by up to 25.53%. Conclusively, this study suggests decoupling policies from absolute transport emissions and focusing on the actual health impact, considering the spatiotemporal relationship between emissions and receptors.

Although tailoring a one-size-fits-all construction logistic plan can initially prove difficult due to the unique character of each construction site’s supply chain, the conducted studies also show that this individual complexity can be overcome by better integrated urban transport planning and can ultimately lead to significant sustainability benefits.

Read the full thesis here.

Source: VU Brussels.

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