published journal article

1,000 HP Electric Drayage Trucks as a Substitute for New Freeway Lanes Construction

Abstract

Electrification of trucking combined with connected technologies promise to cut the cost of freight transportation, reduce its environmental footprint, and make roads safer. If electric trucks are powerful enough to cease behaving as moving bottlenecks, they could also increase the capacity of existing roads and reduce the demand for new road infrastructure, a consequence that has so far been understudied. To explore the potential speed changes of replacing conventional heavy-duty drayage trucks with electric and/or connected trucks, we performed microscopic traffic simulations on a network centered on I-710, the country’s most important economic artery, between the San Pedro Bay Ports and downtown Los Angeles, in Southern California. In addition to a 2012 baseline, we analyzed twelve scenarios for the year 2035, characterized by three levels of road improvements and four types of heavy-duty port trucks (HDPT). Our results show that 1,000 hp electric/hydrogen trucks (eTs) can be a substitute for additional freeway lanes in busy freight corridors. While conventional HDPTs with CACC would only slightly increase network speeds, replacing conventional HDPTs with eTs and improving selected I-710 ramps should be sufficient to absorb the forecasted increases in drayage demand for 2035 without adding a controversial lane to I-710. Our results highlight the importance of accounting for the impacts on the speed of new vehicle technologies in infrastructure planning and suggest shifting funding from building new capacity to financing 1,000 hp connected electric trucks in freight corridors until the market for these vehicles has matured.

published journal article

Clean air in cities: impact of the layout of buildings in urban areas on pedestrian exposure to ultrafine particles from traffic

Abstract

Traffic-related pollutant concentrations are typically much higher in near-roadway microenvironments, and pedestrian and resident exposures to air pollutants can be substantially increased by the short periods of time spent on and near roadways. The design of the built environment plays a critical role in the dispersion of pollutants at street level; after normalizing for traffic, differences of a factor of ~5 have been observed between urban neighborhoods with different built environment characteristics. We examined the effects of different built environment designs on the concentrations of street-level ultrafine particles (UFP) at the scale of several blocks using the Quick Urban and Industrial Complex (QUIC) numerical modeling system. The model was capable of reasonably reproducing the complex ensemble mean 3D air flow patterns and pollutant concentrations in urban areas at fine spatial scale. We evaluated the effects of several built environment designs, changing building heights and spacing while holding total built environment volumes constant. We found that ground-level open space reduces street-level pollutant concentrations. Holding volume/surface area constant, tall buildings clustered together with larger open spaces between buildings resulted in substantially lower pollutant concentrations than buildings in rows. Buildings arranged on a ‘checkerboard’ grid with smaller contiguous open spaces, a configuration with some open space on one of the sides of the roadway at all locations, resulted in the lowest average concentrations for almost all wind directions. Rows usually prohibit mixing for perpendicular and oblique wind directions, even when there are large spaces between them, and clustered buildings have some areas where buildings border both sides of the roadways, inhibiting mixing. The model results suggest that pollutant concentrations drop off rapidly with height in the first 10 m or so above the roadways. In addition, the simulated vertical concentration profiles show a moderately elevated peak at the roof levels of the shorter buildings within the area. Model limitations and suggestions for urban design are both discussed.

policy brief

Informing California Policy for the Three Transportation Revolutions - Shared, Automated, and Electric Vehicles

white paper

Reduce Emissions and Improve Traffic Flow Through Collaborative Autonomy

Abstract

This report explores opportunities for employing autonomous driving technology to dampen stop-and-go waves on freeways. If successful, it could reduce fuel consumption and emissions. This technology was tested in an on-road experiment with 100 vehicles over one week. Public stakeholders were engaged to assess the planning effort and feasibility of taking the technology to the next level: a pilot involving 1000+ vehicles over several months. Considerations included the possible geographical boundaries, target fleets of vehicles, and suitable facilities such as bridges or managed lanes. Flow smoothing technology may improve the user experience and operations of managed lanes or bridges, however, it may require external incentives such as reduced tolls to entice the traveling public to use it. This must be matched with other goals such as verifying vehicle occupancy. It might be possible for some hybrid solution that addresses both challenges to provide a way forward. A concept of operations needs to be developed specifically for a target road geometry and a California partner. This concept should benefit from lessons learned from previous pilot projects and will need to be defined so as to achieve both (1) a penetration rate sufficient to achieve measurable effects; and (2) sufficient quality and quantity of data to confirm benefits.

policy brief

Connected Vehicle Technology and AI Could Help Reduce Highway Congestion through Better Utilization of Park and Ride Facilitie

Abstract

Considerable advancements have been made in traffic management strategies to address highway congestion over the past decades; however, the continuous growth of metropolitan regions has impeded such progress. In response, transportation planners have given special attention to integrated corridor management (ICM), an approach that coordinates various traffic control units (e.g., ramp metering) to optimize their operations along the entire freeway. Emerging connected vehicle (CV) technology is expected to substantially benefit ICM, where vehicles can communicate with each other and surrounding roadway infrastructure. The combined potential of ICM strategies and CVs could be even greater if combined with strategies that leverage underutilized infrastructure (specifically park-and-ride facilities) to reduce the total number of vehicles on the roadway.