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Those Yellow Dots on SF’s Pavement - Explained

Monday, May 23, 2016

Many a San Franciscan has pondered the meaning of the strange yellow dots painted at certain places on the street pavement. Many have resigned to letting them forever remain a mystery.

You know the ones we mean. The big yellow dots, painted in a line, some with arms sticking out and gaps down the middle? Well, as the agency that laid down these esoteric markings, we thought it's time we explain them for your peace of mind.

As you may have noticed, these symbols are always found underneath Muni’s electrified overhead wires. Simply put, they help Muni operators navigate their electric trolley buses and Metro trains through wire junctions.


An electric trolley bus approaches a series of four yellow dot markings on the road pavement.

These yellow dots guide Muni’s electric vehicles, like this trolley bus at Mission and 11th streets. Find out how below.

Among Muni staff, these modified circles tend to go by nicknames -- tadpoles, frying pans, hamburgers and pancakes. No kidding.

But the purpose of these markings is serious. They help operators time their acceleration properly as their electric trolley poles and train pantographs pass through the “breakers” that connect different sections of wire. The arms and gaps on the circles indicate which vehicles they apply to, based on the vehicle type (short or long trolley bus) and the direction of approach.

So now that you know about these “pancakes” and “hamburgers,” spotting them may make you hungry. But they’re also hints at the complex work handled by our operators and the crews that maintain our system around the clock. To safely navigate our streets, trolley and streetcar operators don’t just look left and right for people and other traffic -- they also scan up and down for specific markings and signals as well as objects or damage on the tracks and wires.

And now when you scan the pavement while waiting for a Muni train or trolley bus, you’ll be able to identify San Francisco’s urban tadpoles.

Stay tuned for more answers to Muni’s mysteries.