If you can’t get tickets for May Day, why don’t you add a few more night high-speed trains?

In the past decade, my country's rail transit industry has developed rapidly, with investments of thousands or even trillions of yuan, allowing rail lines in various places to quickly form a network. Whether it is the densely packed subways in cities or the railways across the country, they have greatly facilitated our lives.

However, every year when the holidays begin, train tickets are almost sold out in seconds. As the May Day holiday approaches, the tickets for May 1st are officially on sale today, and the annual holiday ticket-grabbing war has begun again.

As the enthusiasm of passengers to travel is unprecedentedly high this year, data shows that it is no less difficult to buy tickets for popular routes such as Beijing-Shanghai, Chengdu-Xi'an, Shanghai-Wuhan, Shenzhen-Changsha, and Beijing-Qingdao than during the Spring Festival travel rush. Many netizens "complained" about the 12306 APP "waiting list after ticket opening" and "preparation for ten minutes, and tickets are sold out in one second". #12306秒没# became a hot search, attracting widespread attention.

The pressure on railway transportation during the Spring Festival is very high every year (Photo source: Veer Gallery) Some people can't help but wonder:

Why do most conventional and high-speed railways run during the day, but only a few at night? Can't we add more trains at night to ease the transportation pressure?

There is actually a similar question, which is why the city’s subway stops operating at 11 or 12 o’clock at night?

A Fuxing train leaves Tianjin Depot (Photo credit: China State Railway Group Co., Ltd.)

Part 1

Why don’t high-speed trains and subways run at night?

The above two questions actually point to one problem, that is, what is happening on the line when there are no trains at night?

To answer this question, we have to mention a more professional concept - skylight. The "skylight" here is not the window on the top of a car or building as everyone understands it, but a concept exclusive to rail transit.

According to the description of "skylight" in Chapter 3 of the "Regulations on Safety Management of Railway Operating Line Construction", we can know the following definition:

"Skylight refers to the time reserved for construction and maintenance work when the train lines are not drawn or adjusted or reduced in the train operation diagram. It is divided into construction skylight and maintenance skylight according to its use."

For any kind of transportation, maintenance or overhaul is very necessary and important.

(Photo source: Veer Gallery)

It is clearer at a glance. In fact, a very important reason is that the line needs to be maintained and constructed at night, which takes a certain amount of time.

For example, you often see in the news that "the National Railway Company announced that it will adjust the timetable for a certain area at a certain time" , or when buying tickets on 12306, you will find that a train number you often take to go home has a "train timetable adjustment", which leads to a delay in the ticket purchase time. The prerequisites for this type of question are related to the questions in front of this question.

The new operation diagram will be implemented on December 30, 2019 (Photo source: CCTV News)

The so-called timetable adjustment is the adjustment of the train operation diagram, which affects the specific trains that passengers take. There are many reasons for this adjustment, the most typical of which is the transformation of the signal system.

For example, if a few signal machines or sets of switches are added at a certain location on the line due to design changes, the station interlocking logic must be rewritten and the corresponding application software must be upgraded. This is obviously a change in line conditions.

For example, if a line is transferred from one railway bureau to another railway bureau, the dispatching management of the line will be the responsibility of the new dispatching command center, which will be reconnected. This will obviously also be reflected in the center's operation diagram and large screen changes. Accordingly, the dispatching centralized control system (CTC, Centralized Traffic Control System) may need to be modified. Obviously, the above work is not allowed to be performed during the daytime train operation . The specific construction will have to wait until the "construction skylight" time period mentioned above, which is generally at night.

The operators are debugging (Photo source: Sohu.com)

For example, for high-speed railways, the regulations require that the window time should not be less than 240 minutes in principle. However, in practice, taking into account the preparation before construction, the emergency time reserved for construction, and the cleaning and restoration of the site after construction, the default window time is generally between 00:00 and 06:00 in the early morning. This is why you rarely see G/D/C trains departing during this time period.

Fortunately, there are many railway lines, and there is usually more than one transportation line between two cities, so we also have the opportunity to take a "sleeper train" such as the Beijing-Shanghai D7. Departing in the evening and arriving the next morning, in a sense, it satisfies some passengers who often travel for business but are troubled by the red-eye flights.

Of course, in addition to major line maintenance issues that limit rail transit operations at night, passenger volume is also a consideration.

As we all know, both subways and railways, as public infrastructure of cities, have certain public service nature. This is also a main reason why China's high-speed railways/subways are still built even though they will lose money after they are built.

Although rail transit is a public welfare, it also carries a lot of staff who work hard for it. It is obviously unrealistic to rely solely on government subsidies. It is still necessary to create profits on the basis of completing basic tasks. At night, there are fewer passengers and the travel density is low. If the number of railway trains is the same as during the day, it will cause a lot of resource loss. Therefore, reducing the number of night trains is also understandable.

In addition, as we all know, the rail transit industry is a typical "three-shift" work system for operating staff. Although most of the equipment at night is "low-efficiency", the staff on duty are indispensable. Nighttime is the time for people to rest, and their mental state cannot be compared with that during the day. If a large number of trains are operated at night, it will also cause great pressure on the staff themselves.

Part 2

Compared with high-speed rail, the operation time of subway is more restricted

If the vastness of the railway gives us the opportunity to travel at night, the subway seems much more cramped in this regard.

Compared with four-line subways abroad, domestic subways are currently dominated by two lines.

From the perspective of line maintenance, either there is no maintenance, or no trains can run on the track (except for rail cars and trains that cooperate with EMU debugging). Therefore, this is also an important reason why domestic subways cannot operate 24 hours a day. In addition, it is definitely not okay not to maintain the line. After all, the primary responsibility of public transportation is to ensure that passengers can travel safely and reliably. That's right, it's the subway night construction site you imagined:

(Image source: colorhub.me)

Therefore, how to control the maintenance cycle and equipment failure within a certain range is an important issue that urban rail transit has been committed to solving. The corresponding intelligent operation and maintenance system research and development and the application of big data are also constantly helping subway companies improve their capabilities in this regard.

Or one day in the future, without building a fourth line, the subway can achieve intermittent 24-hour operation.

Although my country's rail transit cannot operate 24 hours a day at present, it is constantly exploring more solutions. For example, some first-tier cities have chosen to extend the operating hours of supporting subway lines in order to activate the city's nighttime commercial capabilities. The railways have chosen to add various temporary trains during major holidays, especially during the "phenomenal" traffic during the Spring Festival.

As mentioned in the previous article, some people may wonder why the railway department does not add high-speed trains at night during the Spring Festival travel rush? In fact, there are additional trains. However, compared with trains that depart and arrive during the day, the ticket sales of trains that depart and arrive at night are still worse, because many passengers still need to reverse twice before and after entering/exiting the station. Trains that depart and arrive at night are still not very convenient for cities without large comprehensive transportation hubs.

Finally, I wish everyone can buy tickets and travel happily and smoothly!

High-speed rail in operation (Photo source: Veer Gallery)

Produced by: Science Popularization China

Produced by: Sima Wangtian

Produced by: Computer Network Information Center, Chinese Academy of Sciences (The images with source in this article have been authorized)

This article only represents the author's views and does not represent the position of China Science Expo

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