Assessing the Impact of Calendar Events upon Urban Vehicle Behaviour and Emissions Using Telematics Data

Highlights: This study provides an in-depth examination of the influence of calendar events (Easter holidays) on travel characteristics and vehicular emissions.

What are the main findings?
• During Easter holidays, vehicles exhibited more dynamic driving patterns compared to the average annual periods, with increases in speed (~4%), acceleration (3–4%), and vehicle-specific power (7–9%). The more active driving behaviour resulted in higher emissions per vehicle, with CO₂ and NO₂ emission factors increasing by 3–8% and 4–10%, respectively.
• The effect of Easter holidays on overall CO₂ and NO₂ emissions in 2022 was not uniform across time and location. By integrating road occupancy data, this study revealed contrasting outcomes: major roads experienced substantial decreases in emissions (15–25%) during weekday peak hours, while urban roads saw slight increases during weekend rush periods. This variability highlights the complex interplay between holiday traffic flow patterns and emission levels across different road types and times.

What is the implication of the main finding?
• This study calls into question the assumption that a reduction in traffic automatically results in lower emissions per vehicle. This is evidenced by the observation that individual vehicle emission factors are higher during less congested holiday periods.
• The substantial decline in overall emissions during Easter, despite an increase in per-vehicle emissions, highlights the pivotal role of traffic volume in urban air quality management. This finding suggests that strategies focusing on reducing the number of vehicles on the road, such as promoting public transportation or encouraging remote work during peak periods, may prove more effective in lowering total emissions than solely targeting individual vehicle efficiency in urban environments.

Abstract: Employing vehicle telematics data, this study investigates the transport environment across urban and major road networks during a two-week period encompassing the Easter holidays, considered as a case study. The analysis spans four distinct years: 2016, 2018, 2021, and 2022. Geospatial and Temporal Mapping captured the dependencies of vehicle speed, acceleration, vehicle-specific power (VSP), and emission factors (EFs) for air pollutants (CO₂ and NO_x) on the studied calendar period. The results showed that during the Easter holiday, the median vehicle speeds exceeded annual averages by roughly 5%, indicating a clear deviation from regular traffic patterns. This deviation was particularly stark during the 2021 lockdown, with a significant drop in vehicle presence, leading to less congestion and thus higher speeds and vehicle acceleration. The emissions analyses revealed that individual cars emit higher levels of CO₂ and NO_x during Easter. Specifically, the median values of CO₂ EF and NO_x EF were 9% and 11% higher than the annual norm. When combined with road occupancy data, the results demonstrate that the Easter holidays in 2022 had a variable impact on NO_x and CO₂ emissions, with significant reductions on major roads during weekday rush hours (15–25%) but slight increases on urban roads during weekend periods.