1. What Is a "Never-Opening Crossing" That Stays Closed in Rush Hour?
In the morning rush hour, when the barrier of a railroad crossing goes down, the next train often comes right away, so the barrier does not go up for a long time. The Ministry of Land, Infrastructure, Transport and Tourism calls a crossing where the barrier is down for more than 40 minutes per hour during peak times a "never-opening crossing." There are more than 500 such crossings across the country. [3] Forty minutes is two-thirds of an hour.
In the 1960s, the Chuo Line faced similar problems. As the population grew, the line became very crowded. To add more trains, more tracks were needed, but this made the crossings closed for even longer. It was reported that some crossings on the Chuo Line were open for only about 5 minutes in an hour during rush hour. However, this was true for some crossings, not all of them. [5]
Because of this, the project to add tracks to the Chuo Line was carried out together with a project to raise the tracks onto an elevated bridge. Construction on the elevated section between Nakano and Mitaka started in February 1962. The first elevated section, between Nakano and Ogikubo, was completed on September 20, 1964. [5] The idea of lifting the tracks to solve crossing problems has been used for more than 60 years. But why remove them all together instead of one by one?
2. Why Remove Railroad Crossings by Section Instead of One by One?
A "continuous grade separation project" is a project where a specific section of railway is raised (or put underground) all together to remove multiple crossings at once. Local governments promote this as part of urban planning to improve roads. [1] The Ministry of Land, Infrastructure, Transport and Tourism explains that the goals are to improve car traffic flow and to reconnect city areas that are split by the railway, helping to revitalize the town. [2]
Near Keikyu Kamata Station, there were 28 crossings in a section of about 6.0 km (about 3.7 miles), including those on the Kanpachi-dori road. Fifteen of these were major bottlenecks. They were big causes of chronic traffic jams and the separation of local communities. [6] If you divide 6,000 meters by 28, the crossings were about 214 meters apart.
If you only fix one crossing, the one right next to it remains. If you lift the tracks for the whole section, you can remove all the points where roads and tracks cross at the same time. [6]
Who pays for this? According to guidelines, prefectures and designated cities carry out the project as urban planning. The railway company pays for the part that corresponds to the benefits the railway receives. The local government pays the rest. The railway company does not pay the full amount. [4]
A similar project is happening near Higashimurayama Station on the Seibu Shinjuku Line. They are raising the railway over about 4.5 km (about 2.8 miles) to remove 5 crossings, aiming to fix traffic jams and unite the local area. [8] To raise tracks over such long distances, construction must happen while trains are running. How is this done?
3. How Can a Bridge Be Built for Tracks While Trains Keep Running?
One method for raising tracks is to build temporary tracks next to the current ones, move the trains there, and then build the elevated bridge in the space left behind. However, this method takes time because all the land for the temporary tracks must be acquired before work can start. [6]
The other method is called the "direct elevated construction method." This builds the elevated bridge directly over the active tracks, straddling them. The special feature of this method is that land acquisition and construction can proceed at the same time. [6] Near Keikyu Kamata, this method was used for about 60% of the construction section. [6]
Because construction happens while the railway is operating, serious work is said to be limited to nighttime for safety reasons. [7] In the direct elevated method, trains pass underneath the construction site during the day. What were the conditions at night and during the day?
Note: Construction while trains are running requires strict safety measures. Serious work is limited to nighttime to protect workers and passengers.
4. How Do Workers Build the Bridge in Only 2.5 Hours of Night Closure?
At the Keikyu Kamata site, the time available to cut off the electricity for trains at night was 2.5 hours. The time available to close the tracks for work was 4 hours. [6] Out of 24 hours in a day, only about 10% of the time could be used to cut the power.
During the day, trains pass underneath the elevated bridge under construction at a speed of 120 km/h (about 75 mph). [6] A speed of 120 km/h is about 33 meters per second.
To match these conditions, the construction used precast parts (components made in advance at another location) and special safety management. [6] Work had to be finished in the limited nighttime hours, and during the day, the construction had to not interfere with the trains. Many of the engineering improvements came from these two conditions.
Note: To handle the risk of trains passing overhead, precast parts (made in factories beforehand) were used, and special safety management was applied.
5. Why Does Removing Crossings Along About 6 km Take 16 Years?
The duration of projects near Tokyo has been reported as follows: 18 years for the JR Chuo Main Line between Mitaka and Tachikawa (about 13.1 km or 8.1 miles); 16 years for the area near Keikyu Kamata Station (about 6.0 km or 3.7 miles); and 12 years for the underground conversion near Chofu Station on the Keio Line (about 3.7 km or 2.3 miles). [7] These numbers represent the total project time, not just construction time.
If we look at the time per kilometer, Mitaka to Tachikawa was about 1.4 years per km (18 divided by 13.1). Keikyu Kamata was about 2.7 years per km (16 divided by 6.0). Chofu was about 3.2 years per km (12 divided by 3.7). This shows that a shorter section does not necessarily finish quickly. However, since these examples use different methods (elevated vs. underground), we cannot simply say one is better than the other. [7]
Reasons for the long time include the fact that serious work is limited to nighttime because trains must keep running, and if temporary tracks are used, time is needed to acquire the land along the tracks. [7]
The method of building a bridge directly above active tracks, as seen near Keikyu Kamata, is a way to save time because land acquisition and construction can happen at the same time. [6] The years it takes to reduce crossings and the fact that trains keep running during that time must be considered together.
Note: Project duration does not simply match distance. Differences in method (elevated or underground), land availability, and local conditions mean distance is not the only cause of time.
6. How Can You Measure the Closing Time at a Crossing Near You?
Let us measure the closing time at a nearby railroad crossing. Do this with a guardian, observing from a safe place away from the crossing. Never enter the crossing area or the tracks. [2]
Use a clock to measure the time from when the barrier goes down until it goes up. Measure several times at the same crossing and record the number of closures and the time for each one. You do not need to wait for trains or stay for a long time.
The standard for a "never-opening crossing" is more than 40 minutes closed in one hour during peak times. You can only compare your total closed time to this standard if you observe for a full hour during rush hour. If you record for a shorter time, compare how the number and length of closures change depending on the location and time of day. [3]
If you want to read about continuous grade separation, you can read about the goals of the system on the Ministry of Land, Infrastructure, Transport and Tourism's Urban Bureau page, and read about the construction details in the technical report for Keikyu Kamata. [2] [6]
Safety note: Observe from a safe place (outside the crossing, away from the barrier). Measure with a guardian. Do not attempt to measure alone or take risks.