By Bryant Ficek, PE, PTOE
Late last year, we started a research project on evaluating stop sign compliance. Our goal is to determine clear lines between effective and non-effective stop sign locations. After partnering with multiple cities for this initial round of work, the data collection portion of the project is wrapping up. We have firmly moved into evaluating the data and determining what that data tells us. Our initial work has led to a few interesting nuggets:
- The higher the conflicting volume that opposes the stop sign, the higher the percentage of drivers that complete a full stop. File this one under not surprising, but still good to confirm. It gives more credence to the fact that volume should be a large indicator of appropriate locations for stop signs.
- On the opposite side, when conflicting volume is under 100 vehicles per hour, the percentage of drivers that do not stop at all (full run of the stop sign, not a ‘rolling stop’) is much greater. One location with low conflicting had over 50 percent of drivers blow through the stop sign.
- Traffic volumes, and particularly conflicting volume, is a greater factor than the functional classification of the road. Higher order roads like arterials generally have higher volumes, so the two sometimes go together. However, intersections with similar volumes appear to have similar compliance regardless of whether a crossing or approach street is labeled as an arterial, collector, or local road.
- The presence of pedestrians, whether conflicting or adjacent, has a minor impact on compliance. It seems somewhat similar to conflicting vehicles, but might also be that drivers have come to expect pedestrians.
We have collected a lot of data. On the one hand, we know we were opening the door to a lot of graphs and numbers. On the other hand, we have found a whole lot of ways to spin data and try to find correlations.
Our reviews are on-going and should be complete in the next few weeks. Cars and pedestrians are only a couple of the factors we are exploring. Other intersection characteristics include posted speed limits, sight triangles, and peak versus non-peak hour traffic.
These initial thoughts provide some interesting looks to where our evaluation is headed. No real clear-cut answers, but intriguing possibilities. We are all curious to see where the final numbers shake out. We look forward to sharing our research results in April. Look for a post with the results and information on how to get your copy.
Stop Sign Compliance Research: Phase II
We are already starting work on phase II of our research. A number of cities have already expressed an interest in participating. We are looking for seven additional cities for this second phase, including five cities outside of Minnesota. Each City will get to select three or four locations within their boundaries for our review. For a nominal fee to partially cover our field work (we will cover time for part of the field and all of the necessary engineering).
What’s in it for you?
- 48-hour turning movement counts at the selected intersections
- Rates of stop sign compliance on at least one approach of each selected intersections
- Participation in and recognition of that participation in our research and any subsequent forums where we might present the results (Traffic Corner Tuesday is a natural fit)
- First look at the final document and the ability to point to your own City numbers to hopefully back up statements about unwarranted signs
Interested? We’re looking to add seven more cities to our list. Contact me directly at firstname.lastname@example.org to learn more and add your name to our research list.