Zhang Queming is called "the living bus map" because of his remarkable ability to memorize details of Beijing's transportation system.
Zhang, a conductor on the 387 bus route, helps passengers to find their way around a network that even long-term residents can find confusing.
He tells them the best way to reach their destinations, and gives suggestions for tailored tours of major landmarks.
He has memorized details of more than 900 bus routes and is familiar with the areas surrounding the stops along them.
Beijing Public Transport Holdings, the capital's major bus operator and the company Zhang works for, has 1,085 routes, and Zhang can recall details of 90 percent of them.
"Some bus stops share the same name but are on different roads, and this confuses many passengers," said Zhang, a 34-year-old Beijing native.
"I travel on buses on different routes after work and on weekends, and walk around the stops to gather details about the surroundings."
He has put all of this information, including details of landmarks and major buildings, into a guidebook containing 500,000 words.
The book has been updated several times. The first edition, issued in 2006, contained details of 500 routes, and the latest, released in February, covers more than 900.
The 387 service he works on sets off from the bus station at Beijing West Railway Station, so it often carries visitors from other cities who are not familiar with the capital.
"When tourists ask for details of a trip to a particular place, I see the bus routes and stops immediately in my mind," he said. "It helps me to serve passengers better.
"It's exhausting to walk around the bus stops, but it's worth it to see more people enjoy the capital. My parents pack snacks for me when I go on my bus trips."
His interest in recording bus route information started long before he began working as a conductor.
"I had to change buses three times on the way to my vocational school, and the journey took more than three hours, so I always looked for ways to save time," he said, "Then I began to travel on buses in my free time."
Now he plans to develop a smartphone app based on his guidebook.