William Hui has been fascinated with public transportation for as long as he can remember.
So it only made sense that the 40-year-old systems engineer would challenge himself to travel from his hometown of Vancouver, British Columbia, to Tijuana, Mexico, solely on public buses and trains.
On 24 June, Mr Hui set out to do just that, taking a nine-day journey along the US Pacific coast.
Mr Hui told the BBC he only had a few rules for his trip: absolutely no Greyhound buses or Amtrak trains were allowed, and walking between bus stops had to be kept to a minimum.
“At no point in this trip did I have to walk more than maybe 15 minutes from one bus stop to another,” he told the BBC on Friday.
“It was just remarkable to see how the different services connected, especially in rural areas,” he added.
This was not the first time Mr Hui set out on an unusual journey.
In 2013, he tried to travel as far south from Vancouver as he could, but only made it to Salem, Oregon.
“I wanted to go further, I just couldn’t because there was no transit pretty much crossing Oregon into central California,” Mr Hui said.
But earlier this year, he learned of a new, four-hour bus route that links Eureka, a city in northern California, to another city named Ukiah, about two hours north of San Francisco.
He called that route “the missing link”, which finally allowed him to make the journey all the way to Mexico more than a decade later.
Mr Hui said a lot has changed from that initial trip, including how more public transit buses now are equipped with WiFi and accept credit or debit card payments.
Some, however, still only accept cash. “I went to the currency exchange before I set out on this journey and asked for 50 $1 bills just so I had exact change,” he said.
Another thing Mr Hui noted was the difference between public transport in bigger cities, like Seattle or San Francisco, and smaller rural areas, where one bus would travel several hours to link people over the span of hundreds of kilometres.
When it came to international borders, Mr Hui said he crossed them by foot.
At the US-Canada border, he said he was met with scepticism by border agents as he tried to explain the purpose of his journey.
“There are not that many people who cross the (northern) border by foot,” Mr Hui said.
By contrast, he noticed a more well-travelled route between San Diego, in California, and Tijuana, Mexico, and generally more foot traffic at the southern border.
In all, Mr Hui spent a total of about $200 (£157) on bus tickets. But the views along the way, he said, were priceless.
“I was absolutely amazed by the Oregon coastline when I passed through central Oregon,” he said, and was also “awestruck by the redwoods” as he travelled through northern California.
“And I’ve been saying this to folks who have asked: I was really there for the journey, not so much the destination,” he said.
Mr Hui, who works at TransLink - the transportation authority in Vancouver - said his fascination with public transport stems from his appreciation of the “logistics puzzle” behind transit systems that allow buses and trains to get to their intended destinations on time.
He added that he enjoys the novelty of experiencing a new system of public transport, and the role these systems play in helping connect people from one place to another.
“One thing that struck me on this trip is how important transit is to the communities it serves,” Mr Hui said.
“At no point was I alone on the bus for extended periods of time,” he said.
Another thing that surprised Mr Hui is the minimal delays throughout his trip.
“That was the amazing part,” he said. Even with the notoriously lengthy Los Angeles traffic, Mr Hui said he had enough time to make his next connection and did not have to resort to any back-up plans.
For anyone who wants to set out on a similar journey, Mr Hui advised to research ahead of time and to pack light since there are typically no luggage racks or baggage space available.
He added that it is good to also plan out bathroom breaks.
“Shopping centres, libraries, community centers, those are great places to find a washroom during a short stop,” Mr Hui said.
And perhaps the most important tip: “Know when the bus comes.”