Week 6 - Improving the Simulation
April 13, 2024
Welcome back to the blog folks!
As you may remember from last week, one of the goals was to create detectors that can change signal timing for non-peak hours. However, I soon realized that I wasn’t able to change the type of signal controller, I had optimized it as a fixed time signal and there was no method for me to switch the controller type. So this simulation will be the most effective for peak hours, which still taught me a lot – and hopefully you – about signaling principles.
The other goal for this week, which I was able to accomplish, was to create safe pedestrian crossings. Since I had created the signal phases to be so short it didn’t give enough green time for a pedestrian to cross the roadway in time. So I increased the signal cycle by 15 seconds based on pedestrian interaction, where I was then able to let pedestrians through along with a 2 second buffer between a green light. Which worked! There was one issue I ran into, the right turn, since it crossed two pedestrian crossings that meant there was no time in the signal cycle for cars to take a right turn. Currently, the Fremont & Mowry intersection has 3 lanes for straight bound traffic with the rightmost lane allowing both straight and right-turn traffic. The way that my signal was set up didn’t allow for that and so I had to change the rightmost lane into a right turn only lane. This meant that I was now able to freely let cars take right turns during the left turn phase of the signal cycle. And since there are two left turn lanes the right lane was free to join into the third lane.
One final idea I played with was a pedestrian refuge island. I tried to create an area in between the roadway to create a safe space for pedestrians and to reduce conflict. The way that I had created the signal phases actually protected pedestrians crossing parallel to Mowry through two green phases when heading north. So I only needed to add a pedestrian signal for pedestrians going south, letting Fremont traffic flow through. And then giving the green light again to pedestrians. I also added a refuge island for pedestrians walking parallel to Fremont but this was more to allow right turn traffic through and not build up. All that I have left is to work through some small tweaks with the right turns, whether to input a signal or a stop sign as the right turn seems to be the main cause of congestion for this intersection. Otherwise this simulation is a success!
This week has taught me a lot about the challenges that many city traffic engineers may need to face when trying to upgrade our intersections. Next week, I will work towards figuring out the cost of these upgrades and ways in which our local governments can help finance them.
Tune in next week!
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