The goal of the Intelligent Network Flow Optimization (INFLO) application bundle within the Dynamic Mobility Applications (DMA) Program is to optimize traffic flow through the use of connected vehicle-drawn data. An evaluation was performed to assess the impacts of a prototype of Dynamic Speed Harmonization (SPD-HARM) with Queue Warning (Q-WARN), two component applications of the INFLO bundle.
A previously calibrated VISSIM microsimulation model of an 8.5-mile segment of US-101 freeway in San Mateo, California was used for a "before and after" analysis.
- Modeling was done for six operational scenarios for each of the four different levels of connected vehicle response rates: 0-percent (baseline), 10-percent, 25-percent, and 50-percent (a maximum of 50-percent was used with the implicit assumption that the response rate is the market penetration rate depreciated for communication loss and driver compliance effects.)
- The six scenarios modeled combined a flat median traffic demand level, three possible severity levels of incidents (none, 1 lane closed – 30 min, 1 lane closed – 60 min) and two possible weather types (dry pavement, wet pavement) for the corridor.
- Simulation runs were averaged for each scenario and results were then weighted according to their expected frequency over the course of a year to obtain annualized results.
- The magnitudes of the speed drops (shockwaves) between vehicles was significantly reduced, even at the 10-percent market penetration level.
- Under SPD-HARM, average speeds on freeways were reduced by up to 20-percent, with the greatest impact occurring at the 50-percent connected vehicle level.
- Under severe-congestion conditions (such as during lane-closure incidents), reductions in speed still occurred with the Prototype, but they were less significant than for less-severe conditions.
- There was relatively little effect on vehicle stops.
- There was an increase in the amount of lane changing on the freeway.