Development Type: None
Services Provided: Traffic Signal Tune-Up
Client: City of St. Louis Park
Shortly after introducing our new Traffic Signal Tune-Up service earlier this year, St. Louis Park became our first client to contract with us. In all, they requested we examine 15 signal systems around the City – all local systems with at least a couple years past since being examined.
We followed our standard procedure for this service, which includes turning movement counts, revising the signal timing, and completing basic maintenance. Wrapped up at the end of August, here’s our top five take-aways from this project:
+ Group Adjacent Intersections. Although these intersections all operated independently, the movements at one influenced the movements at another. While that is pretty obvious (especially to drivers), that means it may make more sense to update all signals in a general area rather than chronologically by date of last revision.
+ Coordinate With Other Agencies. Another obvious one that goes along with paying attention to surrounding signal systems. In this case, both the County and the State operated adjacent signals that were not coordinated together. By talking with both agencies, we were able to account for those adjacent operations as well as obtain another perspective on how the City’s study intersections were operating. Both agencies were extremely helpful and made our revisions better because of their help.
+ 48-Hour Counts Make a Difference. We written about longer turning movement counts as part of our standard Traffic Impact Study process. The benefits for this project included being able to better see the length of different peak periods and notice peaks that extended into the evening in the retail areas. Most interesting was reviewing the shifting traffic, in terms of time, between the two days. The average of the two days smoothed those shifts out, allowing our revised signal timing to better accommodate the natural variations in traffic flow.
+ Maintenance Checklist Are Good Planning Tools. Most agencies do not have excess money just waiting to be spent on hidden signal issues. Based on our field reviews, we divided potential improvements into lists of short-term items and long-term concerns to address. The critical items listed in short-term needs included things like fixing detection and push buttons, improve sight distance by trimming nearby vegetation, and updating the cabinet logbook with the most up-to-date information. Long-term needs focused on items that need more planning, such as identifying future interconnect options, improving crossings to full ADA-standards, and reconfirming signal timing when a couple multi-year construction projects are complete. Putting priority on these improvements helps with budget planning and overall scheduling.
+ Lots of Controller Types. We encountered ASC/2, ASC/3, ASC/8000, and EPAC 300 in the cabinets. That made programming interesting as each type has slightly different ways to enter the information. The older controllers also presented issues in terms of clocks that slowly lost time, inability to provide for Flashing Yellow Arrow operation, and a simple loss of some programming options that could improve operations.
As far as we know, our service is the first to pair the retiming with basic maintenance. After completion of this first project, the items reviewed and report prepared have helped the City not only improve traffic operations at the study intersections, but improve safety in both the short- and long-term. As we continue with the next Tune-Up projects, this experience has helped us better focus on the individual intersection needs.