This is a rough set of guidelines for how to make public transport networks more resilient to infectious diseases. While this post is inspired by the Covid-19 pandemic, some of what I’m going to discuss here is relevant to infections in general, both seasonal flu and future generational epidemics.
I’m aiming mainly at people who work for public transport authorities and can act to epidemic-proof their systems in the future, but some of the guidelines may be helpful for riders. The key takeaway is that public officials probably should not want to shut down the system or discourage people from riding it; thus, as a rider you probably shouldn’t avoid the trains except insofar that you should avoid most places you’d take them to, like crowded offices and events.
Finally, let me be clear: my expertise on public health approaches zero. I have a fair amount of general knowledge of how different urban rail systems operate, but more about network design and costs than public health. To the extent I’m ahead of anyone else on this issue, it’s that I’ve seen so much wanton incuriosity in the West (especially the US) toward Asian practices, and therefore asked around for East Asian practices rather than trying to learn worst industry practices from Europe and North America.
The scope of this post
The scope of what best industry practices are on epidemic prevention is, roughly, the high-income major cities of East Asia, plus Singapore. China is excluded on purpose: a country that arrests doctors for telling the public about the coronavirus isn’t really where you want to get disease prevention tips from. Instead, the low infection rates so far in Taiwan, Hong Kong, and Singapore, and South Korea’s ability to control the infection through mass testing after the explosion in cases at the Shincheonji church, suggest that those countries should be the models. Japan may be a good example as well, but the state is undertesting, so the full extent, while apparently lower than in Western countries, may be understated.
I have talked to people in Singapore, Hong Kong, and Seoul to understand the situation on the ground there. In Taipei and the cities of Japan I have not, and am relying on media report; I know I have commenters who live in Japan, so if you have anything to say about the efforts there then please do speak up and contribute, regarding both the measures taken and current infection rates.
This is necessarily a volatile situation. It’s possible that in a month, Germany and France will have controlled the infection while the rich countries of Asia will look as dire as Lombardy looks right now. I don’t think such an inversion is at all likely, but ultimately, I am describing the best information available as of 2020-3-11.
Do people need to stop taking mass transit?
Probably not. I emphasize probably because the different in-scope cities are reacting differently, and we don’t yet know for certain whether avoiding the trains is correlated with greater safety from infection.
In Singapore, life goes on. I have family there; I’m told that the MRT is not less crowded than the usual at rush hour, but the buses are definitely less crowded. The estimate I heard is that 1/3 to 1/2 of the population on the street is wearing surgical masks. Instead of shutting down schools and offices, the state imposed a mandatory quarantine on people arriving from early-infected countries including China, and went as far as revoking the green card of a permanent resident who violated the quarantine.
Update 2020-3-12: my sibling reports that, first, the mask-wearers are largely Chinese, not ethnic minorities like Malays and Indians, and second, ridership on the MRT is noticeably down at rush hour, with some empty seats where normally trains are standing-room only.
In Hong Kong, it is exactly the opposite. The state is not terribly relevant – the population does not trust it. There was early caution due to social memory of SARS, leading to rapid social distancing, closing down schools, offices, and public events. I’ve asked Lyman Stone and Trey Menefee for their impressions. They both said the MTR is empty nowadays, and Lyman reminded me that ridership was down even before the epidemic on account of a popular boycott in response to the company’s collaboration with regime security. The total social distancing means people travel little, but when they do, it’s often by TNC, leading to a lot of Uber traffic; drivers even put hand sanitizer in the back of their cars and make an effort to clean the interior well, to attract passengers afraid of catching the disease.
In Seoul, the situation is different, in that there was a big flare of the epidemic thanks to the so-called patient 31, a member of Shincheonji, who transmitted the virus around the group. Until a few days ago, Korea was the #2 country in the world in confirmed cases, after China, but Italy and Iran have since overtaken it and the US is poised to overtake it soon too. But new infections are down thanks to an aggressive regime of testing. Public transportation is still in operation – Min-Jae Park, an NYU student from Korea who has been working with me and Eric Goldwyn on our construction costs project, said that there is noticeably less ridership according to family but also,
Yesterday, there has been a group of confirmed cases in a same workplace including commuters via transit to and from Seoul. The government did declare that it is almost impossible track back individual patients to show if transit is a hazardous environment. However, since the early stages, the national and local transit authorities has been aggressively sanitized the public realm especially in transit. Additionally, the ridership of the transit decreased overall, as the remote working culture started to become naturalized.
So far, there has not been a substantial case that proves that transit needs to be reduced or shut down, but we shall see how the yesterday’s case turns out. I will update to you if any policy change comes up relating to the virus, but I think that is probably the last thing the government want to do in scale of national lockdown Italy did.
My other source on Korea’s response is Nick Plott, a.k.a. Tasteless, a popular esports caster. In a short video about the virus and its effect on esports, he mentions the effect on Korea, and says that public transport in Seoul is deserted. My hunch is that Min-Jae’s take, although second-hand, is more accurate than Tasteless’s, and public transport in Seoul still has a fair amount of ridership, if not nearly so much as before the pandemic.
Update 2020-3-12: Min-Jae clarifies that as of the morning of the 13th Korea time, there is a shift to private transport even though the government says public transport is safe; he guesses ridership is down 20-30%.
In the big cities of Japan, ridership is down, though not by much relative to the magnitude of the crisis. The media quotes 10-20% declines in ridership on the Yamanote Line and on lines around Osaka, and 20-30% declines in ridership on the Nagoya subway. Maciej Ceglowski is visiting Japan and reports that the trains in Kyoto “are not crowded at all,” adding that about 3/4 of the people wear masks. Japanese office culture is resistant to working from home, as is I think office culture elsewhere in Asia-Pacific, and this has hampered social distancing efforts.
Finally, in Taipei, I do not have any information regarding public transport usage during the pandemic. That said, some circumstantial evidence that it is still going on is that the region has just opened a new circumferential line, the Yellow Line, and even let passengers ride for free for the first month, getting more than a million riders in 25 days, which is low but not outrageously so for a new circumferential line.
How can mass transit be made less infectious in the future?
There are two ways passengers can infect other passengers in public. The first is directly, through coughing, sneezing, or casual touching combined with touching one’s own face. The second is through intermediate surfaces, called fomites in epidemiology, such as poles, seats, door handles. Neither disease vector can be eliminated, but there are design elements that can greatly reduce both.
Infrared sensors for temperature checks
It’s possible to take people’s temperatures passively using infrared sensors. Taipei installed such sensors at one MRT station and is about to do so at six additional central stations. People with fever above 38 degrees will not be allowed into the station, and people with temperature between 37.5 and 38 degrees will have to undergo an ear temperature check to confirm that they do not have a fever. I saw this system at the airport when I visited Taipei three months ago, where it was used to screen passengers with fever.
This system requires all station entrances to be staffed. This may be expensive in smaller cities, but as a temporary measure during an epidemic, it’s fully justified. If you’re the government, you can afford to bust the budget in an emergency to make sure people can travel around the city without contracting a fatal disease.
Temperature checks will miss asymptomatic cases, but this is fine. The epidemiologist-turned-data-scientist Maria Ma summarizes the best available research on Covid-19: while asymptomatic transmission is possible, it requires much closer contact than being together on a train.
Every station entrance should have hand sanitizer in sufficient quantities for the expected passenger traffic. Some office and university buildings already have this solution, even in the West; this is especially common in Singapore. My recollection of Taipei is that it had hand sanitizer at stations even in December, but I am not completely certain this was from Taipei and not Singapore or Bangkok.
Seoul offers disposable chopsticks for pressing elevator buttons. In the short run, transit agencies that use button-operated doors, such as those of Berlin and Paris, should do the same at stations and inside train cars, space permitting. In the long run, European agencies should be more like Asian (or North American) ones and have automatic doors opening at every stop.
In the long run, it’s also beneficial to design train interiors to inhibit the spread of viruses and bacteria. Some materials catch bacterial and viral infections more than others – for example, a 2015 study by Biranjia-Hurdoyal, Deerpaul and Permal finds that synthetic purses have far more bacteria than leather or cloth ones; this should be equally true of train seats. Moreover, the poles should be coated with copper, as it has biocidal and antiviral properties – a 2013 study by Salgado et al finds that coating ER surfaces with copper reduces the risk hospital-acquired infections, from 12.3% to 7.1% when all infections are included or from 8.1% to 3.4% excluding MRSA and VRE.
Fare barriers and station entrances should be designed to minimize fomites. The best option here is not used in Asia: no fare barriers at all, with proof-of-payment fare enforcement. But the smartcard systems and automatic fare barriers so common around Asia are a good second best, as they do not involve physical contact with foreign objects. The worst options are metal turnstiles that passengers turn with their hands, cage-style turnstiles, or heavy doors that passengers must push on their way out; these are found in New York and Paris, and should be replaced to reduce the spread of disease in the future.
Transport companies should clean their vehicles and stations regularly. This may not be realistic at bus stops, but is realistic on buses and trains and at all train stations. That ten-year-old piece of gum stuck to the floor of your New York subway station is not by itself a vector for a virus that only spread to humans three months ago, but if it’s still there, then so is the tissue thrown yesterday by someone who just got sick.
Seoul is using drones to spray disinfectant on hard-to-reach surfaces, such as playgrounds. This can also be used at railyards and elevated rail stations to speed up the process.
The guidelines above are designed for passenger safety. What about employee safety? This, I believe, is a smaller problem, at least in countries that are advanced enough to have good sick leave. It is notable that even in Hong Kong, trains are running, albeit the buses run at lower frequency as people are staying home.
A train driver works sitting alone in a cab separated from where passengers are is not at great risk, and neither is a bus driver separated by a glass screen. There is risk of worker-to-worker infection, especially if drop-in crews are common to control turnaround times, but it’s easier to test workers for fever and send sick ones home with pay than to deploy infrared sensors at every station entrance. As an additional layer of safety on top of temperature checks and generous sick leave, agencies should clean train and bus driver cabs between every crew change.
It’s workers who are together all the time who should not be going to work – that is, the head office. Planners, schedulers, managers, and clerical workers can work remotely, albeit at reduced productivity. Making regular plans to reduce infections during flu season, and planning how to respond to bigger epidemic threats in advance, is therefore useful since it doesn’t stress planning capacity at a time when productivity is the lowest.