How We Optimized Our Way to Better Signal Timing

Guest post by Jonah Finkelstein, EIT Spack Consulting and Bryant Ficek, PE, PTOE, Vice President at Spack Consulting.

Vistro and Synchro are two powerful tools in a traffic engineer’s arsenal. Whether completing traffic studies, intersection analyses, or traffic signal timing, these software packages make our lives much easier and work more efficient. As most traffic engineers know, using traffic analysis software and their optimization tools are more of a starting point for signal timing compared to a ‘one-click’ final solution. For our recent signal retiming projects, we took a detailed look into Vistro’s optimization settings to see how they compared to Synchro’s automatic optimization.

Prior to joining Spack Consulting, Jonah worked exclusively with Synchro while Bryant used Synchro’s tool set prior to switching to Vistro. What we learned was Synchro provides local and coordinated intersection optimization of cycle lengths, split lengths, and offset values. However, through experience and education, we have also learned to completely ignore most of it. If used at all, the optimization was run once after the volumes and phases were in place to provide a start for manual analysis. In other words, the built in signal optimization tool can help get you into the ballpark, but manual optimization is needed to achieve the best signal timing possible. With this in mind, we took a deeper dive into PTV’s Vistro optimization settings to see how they compared.

Much like Synchro, Vistro offers local and coordinated signal optimization. But, within the local optimization tool, the user can define what timings to optimize, either split or split and cycle length optimization, and what range of cycle lengths to analyze. On top of optimization type, there is also an option to optimize the signal either through V/C Balancing or by minimizing the critical movement delay. This gives users flexible options for optimizing the intersection timing, and at least provides more start-off points for manual optimization.

Vistro’s network optimization tool also gives users more control over the initial optimization techniques. Much like Synchro, the network optimization applies to the cycle length, split length, and intersection offsets. Vistro then takes the next step, like its local signal optimization, with a “Define the Objective Function” allowing users to assign weight to vehicle delay and total stops. Both give more flexibility and control in those initial optimization results.

Another useful tool unique to Vistro is the route optimization option. Within Vistro’s main page, users are able to define specific routes to use in signal timing. Once defined, weights can be assigned to each route prior to optimization resulting in more efficient signal timing given to those routes with higher rates. This unique application allows users to identify critical movements in a corridor and have the automatic optimization determine signal timings that focus on those defined routes.

Engineering judgement and signal timing knowledge is a necessary component to provide adjustments for reaching optimal signal performance. Vistro’s in-program optimization tools, much like Synchro’s, helps users quickly get to a starting point for that manual signal optimization. Where Vistro begins to separate itself from Synchro is its ability to focus optimization using the “Objective Functions” tools. The ability to assign weights to delay, total stops, and specific vehicle routes, gives Vistro users more control over the initial optimization resulting in a more focused start and closer result to that final optimization.

Due to these options, we have become more efficient in our signal timing projects and are further convinced of the advantages of using Vistro for all our projects. Plus, we got Jonah hooked on using Vistro for signal timing in a very short amount of time.

If you are interested in using Vistro in your office, you can get $250 off your purchase when you use code SPACK16. Contact PTV for more information about Vistro.

Or check out our FREE case study: How Vistro Improved Our Efficiency by 10%