Traffic Operations Engineering is a discipline of civil engineering which focuses on the safe and efficient mobility of surface transportation systems. Traffic operations engineers leverage skills in communications, human factors, electronics and transportation engineering to address complex traffic congestion challenges. Traffic operations engineering requires knowledge and experience with traffic flow theory, traffic data collection, traffic signal timing optimization software tools, traffic signal control equipment and field devices.
To support our clients we have developed a team of highly qualified traffic operations engineers and specialists that use the latest software and hardware to move traffic safely and efficiently through sound engineering principles.
Our approach to successful retiming projects is to understand the network saturation levels and by having reasonable expectations of what success means. Within this approach, we have a hierarchy of traffic operations plan goals that are part of our philosophy and they are as follows:
- Prevent freeway/expressway ramp backups
- Eliminate gridlock
- Provide/improve progression and reduce overall travel and delay time to increase system throughput
- Additional client goals based on the project
The process shown below allows us to master the more complex aspects of operations as well as deliver successful projects expeditiously.
Our Retiming Process
Step 1 - Determine Project Goals, Define Success, Determine Schedule
- Discussion of project goals, how the project came about and any specific definitions of project success. Identify any project constraints, restraints or special conditions. Determination of project limits, seasonal traffic impacts and resulting data plan.
- Discussion of the handling of pedestrians and openness to sequence changes by time of day.
- Determination of current equipment: traffic controllers, cabinets, communication design, and communication status. Status of system detectors should also be determined as this could impact the data collection phase.
- Development of the Project Schedule to include additional meetings, key delivery dates, any impacts to operations (school year issues), and any other issues associated to schedule.
- Written authorization for our engineers to be on client(s) ROW to perform our work as well as permission to access traffic signal cabinets.
Step 2 – Data Collection and Analysis
- System Machine Counts, 7-day using intrusive (tubes) or
non-intrusive (Wavetronix) platforms
- Turning Movement Counts using Miovision Video Collection Units
o More accurate than people counting traffic
o Ability to collect entire corridor at the same time
- Field Reviews & Controller database uploads
- Saturation Flow Rate studies
- Collect reports from ATMS
- “Before” travel time runs using Tru-Traffic and/or Emerging Technologies like Bluetooth MAC Address matching systems
- Build Baseline Synchro Models
o Intersection geometry (intersection field reviews)
o Turning movement counts (Miovision/Jamar files)
o Existing timings and phasing
o Repeated for various times-of-day (day plan schedule)
Good modeling provides a trustworthy picture of capacity analysis and can minimize the amount of fine-tuning required
Step 3 – Develop Traffic Signal Timing Plans
- Update Basic Timings
- Determine pattern needs
- Make pedestrian decisions
- Review crash records for safety issues
- Update Synchro models and use them for pattern optimization. Balanced data collection and sufficiently detailed modeling provide both cost effective and technically appropriate inputs to the signal timing process. Know the end state and work toward it.
- We always question the results, Synchro is only 40% of the answer (maybe less)
- Utilize Tru-Traffic for offset fine-tuning
- Prepare timings for controller database, determine transition modes, standardize action table, ensure Yellow Trap prevention, etc.
- The use of local controller settings besides just optimizing for cycle offsets and splits provides more opportunities to move traffic.
- Coordination plan testing (diagnostics), test databases in our controllers and cabinets (both part of our laboratory) to address any issues.
- Prepare databases for transfer to client’s ATMS, (special files to preserve existing files as applicable)
Step 4 – Deploy Traffic Signal Timing Plans
- Coordination plan testing (diagnostics), and proper implementation are all key components to smooth, successful retiming efforts
- Implementation day staffed accordingly
- Download plans via ATMS, direct connect or front panel if necessary. This task will not require the support from the maintaining agency.
- Verify proper clock time for controllers
- Drive system using Tru-Traffic to determine if controllers are functioning as desired
- Never allow pattern to operate unobserved
- Goal is to ensure local controllers are operating correctly prior to beginning the fine-tuning process
Step 5 – Fine-tune Traffic Signal Timing Plans
- Use Tru-Traffic to fine-tune pattern timing
- Monitor critical intersections, drive the corridor using Tru-Traffic adjusting necessary settings to achieve goals
o More than just Cycle, Offset, Splits
o Use controller features to achieve goals
o Unique to every system, but knowing the hardware can support the timing plan
- We use ATMS to troubleshoot the system, identify issues, and monitor traffic
- We always want to deploy our timings
- Long days, but we never leave until it's right
- "After" runs using Tru-Traffic and/or Emerging Technologies like Bluetooth MAC Address matching systems
Step 6 – Performance Evaluation
- "Before/After" run comparisons to determine travel time savings with the use of Tru-Traffic and or Emerging Technologies like Bluetooth MAC Address matching systems
- Synchro & SimTraffic Modeling
o Develops Operations on Benefit to Cost ratio analysis
o Provides means to develop implementable recommendations
o Fuel savings comparison develops CO2 and emission impacts
- Safety Benefit Cost Analysis
- Concise report signed and sealed by Professional Engineer
Enhanced skills and applications are acquired continuously. We continue to assess and apply improvements to our process after each project.
Quality Control points throughout each project are in place, supporting an overall Quality Assurance program tailored exclusively for our process. We formalize our SOPs and use checklists to ensure we do not miss critical steps in the procedures.
- Advanced System Operation