Impacts of Reducing Freeway Shockwaves on Fuel Consumption and Emissions Meng Wang, Winnie Daamen, Serge Hoogendoorn, Bart van Arem Department of Transport&Planning February 24, 2019

Outline Introduction Approach Application&Results Conclusions February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Background Increasing congestion Freeway control measures in freeways i.e. SPECIALIST (SPEed ControllIng ALgorIthm using Shockwave Theory) February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Background2 Increasing public concerns on environment and health Both sustainability and throughput should be considered when implementing control measures Question need to be answered: What are the impacts of freeway control measures (i.e. SPECIALIST) on fuel consumption and emissions? February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Problem statement Macroscopic emission models Average trip speed as inputs Estimating emissions for large scale network, i.e. a country or a city Microscopic emission models Microscopic traffic data (speed and acceleration) as inputs Appropriate for estimating emissions at link level We have loop detector data Lack of microscopic traffic data We have loop detector data Possibility to extract microscopic information from them February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Approach Speed map at equidistant output grid of 100m*10s February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Approach-Acceleration estimation Assuming vehicle n enters a grid (i, j) with position and time (xentry,tentry), and travels with a speed as a linear function of speed at spatial cell boundaries Trajectory can be obtained by solving the equation with x(tentry)=xentry Acceleration can be estimated February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Application Assessing the environmental impacts of SPECIALIST A freeway control algorithm dedicated at reducing shockwaves on Dutch freeway Detects traffic states and predicts their future evolution using Shockwave theory Resolves shockwaves by implementing dynamic speed limits at different locations Field implementation since September 2009 On A12 going from the connection with the N11 at Bodegraven up to Harmelen. February 24, 2019

Application- data set Double loop detectors with typical distance of 300 to 600m Time period is morning peaks from 6.00 to 11.00 hours. Weekday data from January to May in 2006 as Before-SPECIALIST situation. Weekday data from September to December in 2009 as After-SPECIALIST situation. Unusual congested days are excluded from the dataset. February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Results Indicators Before After Change Average Flow (veh/h) 4761 4991 4.83% Average Speed (km/h) 91.24 91.75 0.56% Average acceleration (m/s2) 0.023 0.022 -4.35% Standard deviation of acceleration (m/s2) 0.0828 0.0631 -23.79% Average Fuel consumption (veh/100 km) 9.0266 8.9852 -0.46% Average NOx emission (mg/s) 7.7306 8.1590 5.54% Total Fuel Consumption (l) 1.0820e+04 1.1178e+04 3.31% Total NOx emission (g) 3.5092e+04 3.6682e+04 4.53% February 24, 2019

Fuel rate Average speed NOx rate The average fuel consumption rate per vehicle decreased slightly. Clear benefits of average fuel consumption rate in congestion area from 8 to 9 am. Average NOx emission rate per vehicle increased by 5.54% after implementing SPECIALIST. Increase in total fuel consumption and emissions After-SPECIALIST. It is difficult to conclude whether implementing SPECIALIST can reduce total fuel consumptions and emissions in the considered road stretch, for the benefits might be compensated by the increase of demand in the network. February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Conclusions The proposed approach provides a way to estimate fuel consumption and emissions based on macroscopic traffic data Potential application includes assessing the impacts of traffic control measures on sustainability at link level Certain dynamic traffic management measures may have different impacts on different indicators of fuel consumption and emissions. Suggestion: Dynamic traffic management measures should be carefully designed if they are aimed at reducing fuel consumption and emission. February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Thanks! Comments & Questions? February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Fuel consumption with speed&acceleration NOx with speed&acceleration February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning

Detector spacing=500m Detector spacing=1000m February 24, 2019 Meng Wang m.wang@tudelft.nl Department of Transport & Planning