Multilane Microscopic Modeling to Measure Mobility and Safety Consequences of Mixed Traffic in Freeway Weaving Sections

Abstract

Weaving sections are components of highway networks that introduce a heightened likelihood for bottlenecks and collisions. Automated vehicle technology could address this as it holds considerable promise for transportation mobility and safety improvements. However, the implications of combining automated vehicles (AuVs) with traditional human-driven vehicles (HuVs) in weaving freeway sections have not been quantitatively measured. To address this gap, this paper objectively experimented with bidirectional (i.e., longitudinal and lateral) motion dynamics in a microscopic modeling framework to measure the mobility and safety implications for mixed traffic movement in a freeway weaving section. Our research begins by establishing a multilane microscopic model for studied vehicle types (i.e., AuV and HuV) from model predictive control with the provision to form a CACC platoon of AuV vehicles. The proposed modeling framework was tested first with HuV only on a two-lane weaving section and validated using standardized macroscopic parameters from the Highway Capacity Manual. This model was then applied to incrementally expand the AuV share for varying inflow rates of traffic. Simulation results showed that the maximum flow rate through the weaving section was attained at a 65% AuV share. At the same time, steadiness in the average speed of traffic was experienced with increasing AuV share. The results also revealed that a 95% AuV share could reduce potential conflicts by 94.28%. Finally, the results of simulated scenarios were consolidated and scaled to report expected mobility and safety outcomes from the prevailing traffic state and the optimal AuV share for the current inflow rate in weaving sections.

Modeling Framework for Predicting Lane Change Intensity at Freeway Weaving Segments

“…More recently, Ng et al ( 8 ) and Seraj et al ( 9 ) attempted to predict DLCs at the leftmost lanes of a road segment. The sites considered in those studies were sufficiently far away from any ramp influence.…”

4. Alignment with concurrent policy agendas promoting liveability

“…Modelling has also demonstrated that key benefits of CAVs such as reduced collisions and increased throughput can vary according to highway geometry, the ratio of autonomous to human-controlled vehicles, and to the manner in which vehicle algorithms form 'platoons' and the headway between them. 9 In real world, rather than laboratory, conditions, such factors will vary so widely that the precise safety outcomes of CAVs may be very difficult to predict.…”

Estimation of Appropriate Acceleration Lane Length for Safe and Efficient Truck Platooning Operation on Freeway Merge Areas

“…Like previous studies [23][24][25][26][37][38][39][40], this study undertook the simulation by developing a set of micro-simulation models using PTV Vissim. The US FHWA Surrogate Safety Assessment Model (SSAM) is used to assess the safety performance of platooned HCVs on freeway merge areas [41,42].…”