Dear Gabby, How do you make your bus schedules?Posted October 1st, 2019
Gabby is here to share and answer the hundreds of questions you send to her every day. She's your source for the inside scoop on everything you ever needed to know about mastering the art of public transit. Email her at firstname.lastname@example.org.
Foothill Transit just updated its schedules, and it made me wonder: how do you come up with your bus schedules in the first place? How do you decide what to change when you come out with a new Bus Book?
-Wondering in West Covina
Dear Wondering in West Covina,
Good question! How does your bus schedule get made? Your answer has several parts.
Your bus line’s route
So maybe you’ve wondered why your bus serves certain areas but not others. Our planning team looks at how many people are boarding the bus at different stops, and they also use the demographics of each area to make sure we’ve got enough buses going to the most popular places.
We usually try to place bus stops close to services or popular destinations. With local service, we try to space stops at least a quarter of a mile away from each other, because if the bus has to pull over too often, it slows down the whole line.
Have you noticed that, although your bus stops at many locations, not all of them show up on the bus schedule? The stops you see in our Bus Book are called time points. Time points are certain stops which a bus has to leave at a scheduled time.
Just like with planning our routes, we look at our data when we plan our timetables. We want to schedule frequent buses at the times when many people are traveling. But we also want to make sure we’re not sending empty buses when there aren’t many customers, because that would be a wasteful way to spend the money you pay us.
Updates to our schedules
We keep a constant eye on the on-time performance of all our lines. We do this in real-time with a software system called “CAD-AVL”, which stands for Computer Aided Dispatching – Automatic Vehicle Location. You can think of it like the map of cars you see when you open the Uber or Lyft apps, although it’s much more complex. We can also use this software to replay bus trips that happened in the past.
We also communicate with people in the know to get their perspective on how the different lines are performing: your bus operators, the dispatchers, the supervisors, and YOU! When you come out to our Meet the Planner events, speak with a Customer Service Representative, send us an email, or touch base with us on social media, we track all of those comments in software made especially for transit providers. This helps us to see where problems are happening.
When we notice a line is running late or early, we try to figure out what might be causing it. Some common problems for on-time performance are:
- It’s taking longer than usual for customers to board the bus. This can happen when, for example, many customers are paying with cash and don’t have the exact change ready before boarding.
- There is added traffic near a school zone.
- Construction might be causing delays.
- Frequent bus stops located too close to one another, causing the bu operator to lose time pulling in and out of traffic.
Improving on-time performance is often more art than science, because there are so many factors all occurring at once. If we add too much time between time points, the operator will have to wait at the stop to avoid leaving early. Too little time, and the buses will be late. We collect data during the months between service changes, and then look at averages based on specific time periods. Our timing changes throughout the day based on school hours and commute times. These adjustments throughout the day allow operators to adapt to varying congestion patterns.
With all this complexity, you can see why we don’t update our schedules more often! It can take significant time to analyze the data and consider the impacts of potential changes. What’s more, every time we update schedules, we need to work with our bus operators and their employers (we contract out for our operations and maintenance). They make sure they can serve the timetables we create. And finally, we need to communicate the changes with you, which means creating, printing, and distributing tens of thousands of Bus Books!
Sometimes, delays are caused by long-term detours, like the construction on the 10 Freeway. When that happens, we update the “running time”, which is the time a bus is supposed to take to get from the start of the route to the end.
When planning a detour, the goal is to try to get the bus as close to as many current bus stops as possible. As you know if you spend much time in downtown Los Angeles, the frequent closing of stops there is a real challenge due to one-way streets and limited turns that the buses can safely make. In most cases, a stop can be temporarily moved without interfering too much with the entire route.