If you are only using one section, it is the same for both. But otherwise, the tabulated speed would be closer to the “real sense of total travel time. Note that if you use the “operating kilometer” figure in the timetable for your calculations, you may not get the correct figure, but we will explain why another time.
On the other hand, the “surface speed” includes the time spent at each stop along the way. The actual kilometers from Tokyo to Shin-Osaka and Hakata are 515.4 km and 1,069.1 km, respectively, which is a difference of 553.7 km. This figure includes stops at Okayama, Hiroshima, and Kokura stations, so it is lower than the average speed between stations shown above.
The first and easiest to understand is the “average speed. This figure is for a “single travel section” with no stops along the way. When the 500 Series started commercial operation on the Sanyo Shinkansen as “Nozomi,” the “time required between Hiroshima and Kokura, 44 minutes, average speed 261.8 km” was entered in the Guinness Book of Records as a world record in 1997. The actual kilometers from Tokyo to Hiroshima and Kokura are 821.2 km and 1013.2 km, respectively, so the difference is 192 km, and the average speed can be calculated as “192 ÷ (44 ÷ 60)” since the train takes 44 minutes to travel that distance.
Now. The purpose of increasing speed is to “reduce total travel time,” not to “compete for the highest speed. Even if the maximum speed is the best in the world, if it is not effective in reducing the total travel time, the maximum speed is only a “symbol”. The indicators that we would like to focus on are the “constant speed” and the “average speed. Both of these terms are frequently used in the railroad industry. They are calculated by dividing the distance by the time, but the subject matter of the two is different.
When it comes to measuring train speed, attention is often focused on the maximum speed. However, even if the maximum speed is high at face value, it will not be effective if the distance or section where it can be demonstrated is short. For this reason, the new E8 Series for the Yamagata Shinkansen has a maximum speed of 300 km/h instead of 320 km/h, and the design margin created by this is used to increase capacity. This was done to achieve a balance between speed and transport capacity.
Can you find the speed without GPS speed measurement app?
By the way, have you ever been on a train and suddenly wondered, “How fast is the train going? Have you ever wondered how fast the train is going?
When I wrote my previous test drive report on the HC85 Series, I asked myself, “I heard that the HC85 Series is the first hybrid vehicle capable of 120 km/h, but what is it really like?” I was curious, so I tried a speed measurement application that uses a smartphone’s built-in GPS receiver.
However, there are times when you don’t need to rely on such a civilized device to determine the speed at which you are traveling. A clue to this is the “joint sound. The rails used in railroads are called “fixed length rails” and are 25 m long, and the boundary between adjacent rails has a small gap between them as shown in the following picture.
The sound is emitted when the wheels roll over and pass over these joints. And since the bogie is generally a two-axle bogie, i.e., two sets of wheel axles on one bogie, the “da-da-da-da” sound is made when they pass through the joint in succession. Since the distance between the two bogies across the coupling is short and the distance between the two bogies across the middle of the car is long, the joint sound is a repetition of “da-da-da-da-da-da”.
So why are there gaps? Because rails are made of steel, they expand and contract with changes in temperature. In winter, when the temperature is low, the rails contract and the gap widens, and in summer, when the temperature is high, the rails extend and the gap narrows. It is necessary to provide an appropriate gap to accommodate the amount of expansion and contraction throughout the year.
If the distance between these joints is 25 m as is standard for fixed length rails, the speed can be determined by measuring the joint sound interval. 1 second interval is 25 m per second, or 90 km/h if converted to mph. The formula is “3600 ÷ joint sound interval (seconds) × 25 (m) ÷ 1000 = speed (km/h). However, the length of the rail may not always be exactly 25 meters depending on the location, so this is only a rough guide.
When photographing trains along the line, the length can also be calculated by finding and counting the number of joints in this fixed scale rail. 4 pieces of 25m fixed scale rail is 100m, which is the equivalent of 5 cars on a conventional JR line.
However, the joint noise means that there is shock and vibration. In fact, joints are more likely to damage the track than other parts and are undesirable from the standpoint of comfort. Therefore, rails are welded to rails to eliminate joints in many cases. This type of rail is used especially on Shinkansen bullet trains, where the rails on the main line are basically of this type. There are some exceptions.
However, it is not possible to have a single rail throughout the entire section, so there are boundaries where appropriate. However, instead of a joint as shown in the photo above, one of the rails is cut at an angle, and an adjacent rail is placed on the outside of the rail to absorb expansion and contraction. This is called an expansion and contraction joint, but there is no gap, so the joint does not make a sound.
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