Why are Manholes on the Best Line of the Motorcycle?


Why is there a manhole on our line?Do you have any idea how slippery a manhole can be on a rainy day? If you know, why would you put it in the most inappropriate place? Is this harassment of motorcyclists?

You can't help but think so, with manholes appearing on the best lines as if they were intended. All riders have experienced the appearance of manholes in the worst places, such as the braking position, the apex of a corner, or the position where you open the throttle at the exit of a turn, and so many others, that it seems like they are really doing it on purpose.

There's a reason why manholes appear in the worst places.

WebiQ is here to bring you a little satisfaction and motorcycle knowledge. In this issue, we're going to explore the mystery of manholes.

Manhole is dangerous.

Riders are basically dominant, but I have yet to meet a rider who says he loves manholes. Even motard riders who love to slide say they hate manholes.

The reason all riders hate them, of course, is because they are slippery. They put patterns on them to make them less slippery, but they are still very slippery. A rainy day is the worst, it's like riding on a wet and slippery steel plate, so of course, it's super slippery.

A straight line would be better.

Manholes, even in a straight line, before an intersection or a stop line, where you have to apply the brakes, are a formidable enemy. We have all had the experience of feeling a sense of urgency when the tires lock unexpectedly (or ABS in modern vehicles) on a rainy night or when you can't see them because of the reflection of city lights.

The ones in the middle of the curve are the worst.

They are the worst, and they are also the ones that exist on the easiest lines to drive. You can still see them at the entrance of a curve, but if they are on the outside of a clipping or a rise in the middle of a turn, there is no way to avoid them, and they can slip and slide, which is very exciting. In the worst-case scenario, you might even fall down.

When I was a beginner, my eyes would be fixed on the manhole and my body would freeze up like a statue of the Earth. ...... I was really scared.

What are manholes for?

I don't need to explain this one. It is a sewer inspection opening. A manhole with a hole (i.e., a hole) for a person (i.e., a man) to pass through.

In addition, water, gas, electricity, telephone, rainwater, etc., may be run through pipes separate from the sewer system, and each has a manhole for passage inspection.

Characteristics of manhole locations on straight roads

On a wide two-lane road, you should be concentrating on one lane.

The reason for this is that when you open a manhole for inspection or other purposes, you have to restrict the lane. If you focus on one side. It only takes one side to regulate it.

So why don't you just put it on the sidewalk!But if you restrict the sidewalk for inspection, you have to direct pedestrians to the roadway, right? It's a pain in the ass just to regulate the lanes. It's just going to be more trouble than it's worth.That's why they are not installed on the sidewalk.

However, recently built roads are often wider, so they are installed underneath the sidewalk in such cases. If you can regulate half the sidewalk and still have no trouble with people coming and going, you don't have to regulate the lanes, and it's the safest way to reduce the number of accidents where vehicles run into each other during inspections.

Characteristics of manhole locations on curves

The sewage system does not use pumps and other equipment to pump sewage, but only the volume, momentum, and difference in elevation of the wastewater from each household. So, the plumbing must be arranged as linearly as possible.If it's just water, it's because sewage is full of all sorts of things flowing through it, and if it's bent up, it will get clogged.

Assuming that a straight pathway is buried underground, it is not a good idea to penetrate underneath each home. That's why it's buried under the road. The roads are basically straight, so it's convenient. And this "extremely straight piping structure buried under the road" is the true nature of the manhole arrangement in the corner.

There are curves in the road and intersections. What happens when you try to connect that in a straight line...

It goes like this.


First, here's a diagram of the right corner. The gray area is the road and the yellow line is the centerline that prohibits overtaking. Then the dashed blue line is the line we want to go through.

We enter from the left end there, passing close to the apex, while accelerating out towards the left end in a reasonable manner.......

It's not a line to swoop in like an idiot or anything, but you want to turn with as big an earl as possible to reduce the bank angle to avoid tipping over as much as possible. You don't want to lean just short of the centerline for the possibility of oncoming traffic to overhang you. I don't want to use the full outside where the sand might be floating. Then, inevitably, the line should be something like this

Now, if we overlap the sewer pipes buried under the road...

Oops!The red dashed line is the sewer pipe and the red circle is the manhole. There's a manhole in the worst possible position!

However, this is actually a bit of a special case, and it is actually avoided to be connected at a right angle of 90 degrees. It's not going to flow well. So what does normal, common plumbing look like?

This is what happens ver..2

This is a diagram of the left corner on the same curve. The dashed blue line is the line we want to go through.

If you put a loose change of direction point in there that is not 90 degrees...

I knew there was a manhole in the most inopportune position!

Manhole provisions

So now you understand that this super-important infrastructure for life was designed to work properly and is destined to result in manholes appearing on the lines of us motorcyclists. It's not bullying or harassment, it's just that the optimal solution to the sewer system has been matched by the worst of us riders. I can't blame them, because they're both 'trying to turn on the best line possible'.

It's important for us riders to know that "this is how manholes exist". If we know this, we can enter a curve with this in mind. It's just a matter of leaving a safety margin for that amount of time, and it goes back to the story that you shouldn't enter a curve so fast that you can't avoid a manhole.

If you can't avoid a suddenly appearing (seemingly) manhole, there's no way you'll be able to avoid it when a child jumps out, etc. You are not supposed to enter a curve at such a speed.

Why there's a manhole at the change of direction

I understand that the sewer is under the road in a linear arrangement. But doesn't it have to be a manhole at the change of direction? Some of you may be wondering, "What is the reason for this?". Unfortunately, there are unavoidable reasons for this.

As I have already written, sewage flows naturally without a pump. If there is a bend in the road, it can still get clogged.

When it gets clogged, you have to unclog it. And the best way to do that is for people to crawl into the clogged area and remove it directly! So the holes (i.e., manholes) that people enter for inspection should be placed at the refractive points of the pipes.

Also, there are times when you have to bend 90 degrees, as shown in the diagram on the right corner. Additionally, the road is not flat and has elevation changes. Sewage has to flow naturally in the first place, so the sewage pipes themselves need to be elevated and low. To solve all of these at once, do the following

The sewage flowing from the right is dropped into a vertical shaft to absorb the difference in elevation, while the pipes are redirected to the left. Putting a lid on top of this vertical shaft would be great for inspection and maintenance, right? The cover on top of the shaft is the manhole.

You can see how convenient it is that multiple thin sewage pipes can be freely controlled to go downstream after they have merged at different elevations in a vertical shaft.

What about overseas?

It's similar to Japan, even though abroad it's uncertain! There is no significant difference between the two.

There are so many differences between cities in the same country that you can't sum up the whole country as "overseas is uncertain". For example, the old cobblestone roads in Europe have no choice but to run sewage through the middle of the road, and there are still sewage pathways that are hundreds of years old that are still in use, to begin with.

In a country as vast as the United States, it would seem that the pipes could be run freely, but again, each city is made up differently. In older, narrower cities, sewer pipes are placed under the roadway as in Japan, but in more modern cities in the suburbs, they are placed under the sidewalk to take advantage of the large area.

This situation is exactly the same in Japan. The way the sewage pipes are threaded depends on the history of the city's creation.

However, many of the cobblestone streets, which are common in old European cities, have been polished to a smooth surface by years of traffic. The entire road is like a manhole.If it rains, the entire surface will be slippery and lousy. I suppose hard, non-deforming cobblestones were best in the days when carriages rolled on hard tires.

The road surface is basically cleaner in Japan, even if it is paved with asphalt, and I feel that there are fewer steps in manholes in Japan. It's not just the manhole situation. Japan has the best roads in the world.


The image above is of a certain corner that exists on my route to work.

There are probably a total of three pipes of some kind buried there in addition to the sewage, but it's filled with a huge number of manholes anyway. It's already horrible.Especially on the right side of the image, there is a series of manholes arranged in parallel in the "downhill" direction, which can be very difficult on rainy nights because of the weak streetlights and the downhill slope. It's kind of reverse-banked, and when I first went through it, I was pretty freaked out.

But since this is a perimeter circuit in a residential neighborhood (which is probably why there are so many large sewer pipes running through it and many manholes), the speed is quite modest. Now I enjoy how they run through the manhole gaps in a glorious way. It's not a very complimentary thing to do, but sometimes I'll deliberately ride a manhole on a rainy day and slide around a bit.

It's the worst manhole placement, but it can be fun too, right? If you were to compare it to a difficult game, it would be like trying your best with the weakest equipment or daring to challenge a difficult mountain with no oxygen alone. It's not as extreme as that, but it's still a good idea to find the best line that avoids manholes and ensures safety, and so on. Exploring clever riding is a fun way to ride on public roads, so I recommend it.

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