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Dear Gabby, how do you plan detours?

Posted March 28th, 2019
Dear Gabby Transit Advice

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

Dear Gabby,

There was construction on my way to school last week, and my bus had to take another route. Who decided on that detour? I would have gone a different way.

-Detouring in Diamond Bar

Dear Detouring in Diamond Bar,

ReroutingHave you ever been in a car following GPS directions when you come across an unexpected event, and you have to find a new way around? It’s pretty fast and easy. The GPS tells you it’s rerouting, and suddenly you’ve got a whole new set of directions to get you to your destination.

Rerouting a bus line is not nearly as quick or as easy, but we have just as many road obstacles as cars do. So what does it take to plan a detour for a Foothill Transit bus line?

Just like everything else we do here, our first job is to keep our customers and operators safe. Customers need safe places to get on and off their buses. Bus operators need to be able to make safe turns – and some of our buses are 60 feet long. That’s a full 15 feet longer than a school bus! Here’s how we get started.

Customer tweet about a crash affecting serviceThe first step is simply finding out about the closure! We work on building strong relationships with cities, construction and filming coordinators, and other transit agencies. That way we can find out about road closures as soon as possible. But our buses serve more than 20 different cities, so we also depend on our bus operators to tell us whenever their routes are blocked or they see signs for upcoming events or construction. And sometimes we learn about closures from awesome customers like you. You rock! When we find out about a closure, we need to know what streets are closed and when it’s expected to begin and end. Roads are often closed long before an event starts and long after it ends. With crashes or construction, there may not even be a fixed end time. Some events, like marches, are especially complicated. Marches don’t stay in one place, and they can be unpredictable.

Once we learn of a closure, our bus operators can’t just pull out Google Maps or Waze for a new route like a car driver can. You’re going to need to know where to pick up your bus, right? The bus operators who are going to serve later trips on that same line will need to know about the closure and follow the same detour. And if it’s an unexpected closure, our planning team can try to contact the organizers of the event or construction for more information. So we all need to be on the same page.

Lane closure

When supervisors plan a detour, they have so much to think about. Are the roads one-way? (DTLA, I’m looking at you.) Can our longest buses safely make all the turns on the new route? Which bus stops will we miss during the detour? Are there safe locations for alternate bus stops that all of our customers can access? Then they need to decide when the detour will start and end. Some of our customers won’t have access to the internet, email, or text messages during a detour. Supervisors and facilities technicians need enough time to drive to each bus stop and post signs before a detour and take them down afterwards. And all our customers need enough time to get to the right locations when a detour starts or ends. Sometimes, we’ll decide to keep detouring even though streets have cleared to make sure there’s no confusion about where people need to catch their buses. Also, did you know our buses are actually operated by two different agencies? Both of those agencies need to communicate with each other and with the staff at the Foothill Transit administrative offices to make sure we’re all working together.

Got that all straight? Yeah, it’s a lot.

Rider Alert text messageBut wait, there’s more! All that planning then needs to be communicated to you, our customers. Depending on the timing and the size of the detour, we might post hand-written temporary signs or printed, laminated signs at your bus stops. If we’re posting the signs long before the detour starts, we need to keep an eye out to replace any signs that get taken down. (It happens.) For big detours with lots of advance notice, like DTLA May Day events, we might post Rider Alerts on board our buses (right behind the operator’s seat). All of our detours are listed on our website at /news/rider-alerts/ and on our Twitter account. And a lot of our customers get an email or text whenever the line they ride has a detour. You can, too – sign up at /news/e-notice/. All the cool kids are doing it.

So the next time your bus has to detour, you can say a word of thanks that all you have to think about is where your bus will be stopping. The rest is up to us.

Glad to go good places with you,


Dear Gabby is our transit advice column. Gabby will give you the inside scoop on everything you ever needed to know to master the art of public transit. See you next time!

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Categories: Commuters, Dear Gabby, Schedules