Traffic Operations and Microsimulations
Traffic operations analysis bridges the gap between transportation planning and traffic engineering/design. CHS senior transportation planners and traffic engineers offer more than 25 years of experience in analyzing traffic operations in saturated urban environments to develop realistic solutions to complex traffic problems.
CHS transportation planners and engineers use state-of-the-art microscopic simulation software such as Transit, Synchro, CORSIM, and VISSIM to effectively convey the benefits and impacts of various transportation solutions. These software programs provide animated visual presentations of how traffic flows and how queues form and dissipate. Our staff often use them to present recommendations to decision-makers as well as the general public.
Areas of Expertise
Arterial Road Operations and Simulation Analysis
Signal Timing and Phasing Analysis
Freeway Operations and Simulation Analysis
Vehicle Queuing Analysis
North Hollywood to Pasadena Bus Rapid Transit Planning and Environmental Study
Project Overview
In 2017, the Los Angeles County Metropolitan Transportation Authority (LA Metro) initiated a study of bus rapid transit (BRT) between the communities of Pasadena and North Hollywood. This service would utilize the State Route 134 freeway (SR-134) or arterial streets in the same corridor that are generally parallel with the freeway. The study involves defining the purpose and need of the project, developing alternative alignments, conceptualizing engineering improvements, detailing the operation of buses providing BRT service, and writing an environmental impact report.
CHS Role
CHS Consulting Group led several of the study’s key tasks. The first involved the development of evaluation criteria to evaluate route alternatives that had been developed in previous studies of the SR-134 corridor and selecting the most appropriate ones to be studied in the environmental document. The second involved determining potential parking impacts of the BRT service and potentially mitigating them by replacing lost parking along side streets.
CHS is currently collaborating with Kimley Horn on detailed VISSIM micro-simulation analysis for several segments in Burbank where vehicle queueing was a key concern for local stakeholders as well as SYNCHRO/SimTraffic analyses for two segments in the Eagle Rock neighborhood where residents were worried about traffic diversion. The results of both analyses were instrumental in helping stakeholders better understand the project and achieve consensus for the proposed design.
Oakland/Alameda Access Project
Project Overview
The purpose of this project is to improve vehicular access to and from the City of Alameda and I-880. Alameda traffic also has a major impact on nearby Oakland Chinatown, which has high volumes of pedestrian traffic and a large elderly population. Pedestrian and vehicular conflicts are a primary reason why several core intersections in Oakland Chinatown have the highest collision rates in Oakland.
Differing perspectives from key stakeholders were a major reason why the project had been studied four times since 2000 but had failed to reach a consensus. In 2017, Alameda CTC made its 5th attempt to move this project to the PAED phase.
CHS Role
CHS Consulting Group has been involved in this project over the past 20 years. The current effort resurrected a detailed geometric and safety study of an option that was preferred by Oakland Chinatown community leaders but had previously been deemed unfeasible. CHS was responsible for a detailed traffic operations/simulation analysis that covers 56 intersections in both Oakland and Alameda. The signal analysis required detailed SimTraffic validation and calibration of vehicle queue length and durations, especially the Jason Street on-ramp to I-880. The project also involved the development of future traffic operations analysis for the years 2025 and 2045, with and without the proposed improvements. CHS’s analyses were accepted by Alameda CTC and Caltrans and the project is now moving forward to the 65% design phase.
Monterey Road Signal Retiming
Project Overview
The City of San Jose obtained a grant to retime and synchronize 24 traffic signals on Monterey Road to improve multi‐modal mobility by reducing traffic signal cycle lengths and pedestrian delay, promoting pedestrian mobility, and improving pedestrian safety. The signal retiming is also expected to reduce vehicle travel time, vehicle emissions harmful to air quality, and greenhouse gas emissions.
CHS Role
CHS Consulting Group was awarded this project as part of its current on-call contract with the City of San Jose. CHS’s work required updating the city’s Synchro model to reflect current conditions, including vehicular, bicycle, and pedestrian volumes as well as turning movement counts.
The key challenges for the project were to balance pedestrian safe crossing needs with the need to minimize vehicular delay and maintain signal synchronization. CHS worked closely with city staff and tested a number of options to optimize signal timing, including optimizing by direction and by a group of adjacent intersections while maintaining the shortest possible cycle length.
CHS conducted floating car runs in both directions during each peak period both before the project and after the proposed signal timing plan was implemented. During the weekday AM peak period, the southbound travel time on Monterey Road was reduced by 13% and delay was reduced by 34%. During other periods, results show travel time and delay have slightly increased due to shorter cycle lengths. This is expected, as the primary goal of the project is to improve pedestrian safety by reducing cycle lengths. A shorter cycle length would result in more and longer red and yellow time per hour, and therefore reduce green time for each signal. The travel time increases were managed to be within 5% for most directions during weekday and weekend midday periods, and within 15% for peak directions during weekday AM and PM peak periods. Fuel consumption and emissions were decreased by up to 17% during the weekday AM peak period.
