The other day I was speaking to a Korean friend of mine and he was telling me about Seoul's new GTX-A commuter railway line. This line opened at the end of 2024 and is part of a broader Great Train eXpress initiative that includes 3 lines (A, B, and C) and that is intended to establish a new "30-minute commute zone" surrounding Seoul. A is the first line to open. C is scheduled for completion in 2030. And already, three more lines are now being planned: D, E, and F.

What this first line has accomplished is pretty extraordinary. GTX-A connects Paju in the north to Seoul in the south. Paju sits at the northern border of South Korea (and therefore houses many US and South Korean Army bases) and has a population of over half a million people. Prior to GTX-A opening, this commute used to take approximately 90 minutes by conventional subway and up to 90 minutes by car, depending on traffic.

Today it takes exactly 22 minutes! If you're interested in seeing a complete walking video of this commute, click here.

The GTX system is a higher-speed railway line. Meaning, the trains are designed to operate up to a maximum speed of 180 km/h. Average speeds vary depending on the segment and stop spacing, but it seems to operate at an average speed of around 100 km/h. Paju to Seoul, for example, is around 33 km. So at 22 minutes, that's a blended average of 90 km/h. This means that there's no faster way to travel between these two points.

What this also means is that, as new GTX lines continue to come online, the geography of the Seoul urban region will continue to get redrawn. Suburban regions that were previously far out, are now going to get "pulled in" and function as more integral parts of a contiguous city. This improved access should also alleviate housing pressures by effectively opening up more supply.

I mean, 22 minutes is nothing. It can take longer than this to travel 3 blocks on a Toronto streetcar during rush hour. GTX is a prime example of the magic of rail and what's possible once you accept that highways (and tunnels underneath them) aren't going to be what efficiently move the most number of people around a big global city.

Cover photo by Ethan Brooke on Unsplash

The Financial Times published the following chart last night. It shows the cumulative number of COVID-19 cases around the world, across the number of days since the 100th case in that particular country. The message here is that most western countries appear to be on a similar trajectory. (The grey dotted line represents a 33% daily increase.) Whereas in Asia, and in particular Hong Kong and Singapore, they have seemingly managed to slow the spread.

Now, there are a number of possible explanations for the outliers; everything from stricter quarantine rules to more rigorous testing. There's also an argument that Hong Kong and Singapore were better prepared as a result of the SARS outbreak in 2002. (More on these explanations, here.) But the other factor at play seems to be climate.

A recent study (by Jingyuan Wang, Ke Tang, Kai Feng, and Weifeng Lv) has concluded that, like the flu, the transmission of COVID-19 appears to be significantly impacted by both air temperature and relative humidity. In their research, they looked at the reproductive number (R), or the severity of infectiousness, for all Chinese cities with more than 40 cases between January 21 to 23, 2020. (Large-scale government interventions began on January 24, 2020 and would have therefore skewed the numbers.)

What they found was that for every one degree Celsius increase in temperature and every one degree Celsius increase in relative humidity, the reproductive numbers drop by 0.0383 and 0.0224, respectively. Air temperature, in other words, has more of a positive impact on containing spread than relative humidity -- which feels right. That is also apparent when you look at the above charts. Take note of Korea, Iran, and Italy near the top left corner of the temperature chart.

If you'd like to download a full copy of the research paper, click here.

I just spent the last 7 minutes listening to this brief historical overview of Seoul by The Urbanist, while I bounced around the city on Google Street View, admiring the coverage of their transit network and the density of their low-rise neighborhoods. 

I love Street View and I love using it to explore cities.

One of the things I liked about The Urbanist episode –  beyond it being a good soundtrack while I explored – is that it talks, albeit briefly, about why Seoul is located where it is today. 

I am always curious about this when it comes to cities. I mean, who was it that decided, yup, this is going to be the spot. Because it’s generally a pretty sticky decision once it is made.

You may also find this 2014 NASA photograph of the Korean Peninsula interesting. The nighttime sky renders up a pretty stark contrast between North Korea and South Korea.

According to NASA, per capita power consumption in North Korea and South Korea is 739 kilowatt hours and 10,161 kilowatt hours, respectively. That’s why the satellite photo looks the way it does.