And these wooden wheels are more likely to slip on concrete surfaces, especially on rainy days.

Therefore, these young people riding bicycles are prone to falling if they ride too fast or make a slight turn.

Especially since they ride very fast, traffic chaos can occur at some intersections.

In such situations, if they brake suddenly, they will almost always fall, and in severe cases, there may even be collisions between bicycles, or even collisions with pedestrians.

As such accidents become more frequent, the public's concerns about the safety hazards of bicycles are growing louder.

Seeing that it had already begun to have very negative effects, the imperial court also began to worry.

If these highly dangerous bicycles were promoted nationwide, how many people would suffer from accidents caused by bicycles?

When this issue reached the ears of Zhu Yunwen and Zhu Yuanzhang, it naturally attracted their attention.

Zhu Yunwen, in particular, was extremely familiar with the term "traffic accident".

In the imperial court, as some officials began discussing whether to stop bicycle production and replace them all with tricycles, Zhu Yunwen stood up and said:

"The birth of anything is not the cause of disaster. These casualties occur because the public lacks safety awareness, not because of the vehicles themselves."

Furthermore, to eliminate these safety hazards, some rules need to be established. Therefore, I have decided that, starting today, red and green flags will be placed at some intersections in Beijing.

Upon hearing these three unfamiliar words, the ministers were all puzzled, wondering what they meant.

However, Zhu Yunwen did not give a direct explanation, but instead ordered people to prepare two different colored flags, red and green.

Then prepare an automatic hourglass.

Automatic hourglasses are actually a very easy concept to understand; they already existed in the Ming Dynasty.

As the name suggests, it is an hourglass that can automatically turn up and down.

The principle is very simple: fix an hourglass in a small wooden frame.

The middle position allows the hourglass to be flipped up and down.

Once all the sand in the hourglass has fallen to the bottom, a small mechanism will be triggered, allowing the two to switch places.

Transfer the bottom part, which is full of sand, to the top, and then let the sand flow from the top into the empty hourglass at the bottom.

Such an hourglass can be used for automatic timekeeping over long periods of time.

It is also highly automated because it can cycle multiple times.

After Zhu Yunwen obtained the automatic hourglass and the two flags, red and green, he placed a red flag on the left side of the hourglass and a green flag on the right side.

Then, similarly, place a green flag on the left side of the hourglass below and a red flag on the right side.

After the four flags were planted, Zhu Yunwen addressed his civil and military officials:

"Place this device in the middle of the intersection, and as the hourglass drips, the top and bottom will reverse."

After one minute, when the hourglass has completely run out of sand and is reversed, the two flags stuck in the bottom of the hourglass will quickly move to the top.

A flag directs traffic at an intersection. If the flag on the left is green, then traffic is allowed on that side. If the flag on the right is red, then traffic is prohibited on that side.

Then, the flags are switched again after one minute. The flag on the left turns red, indicating no passage, while the flag on the right turns green, indicating passage is permitted.

"I think you all understand what I'm saying, right?"

If it were just a matter of speaking, the people might not be able to understand. But Zhu Yunwen demonstrated with an hourglass and a flag, and everyone immediately nodded in approval.

I think that having something like this at an intersection would allow for the control of traffic in all four directions at once.

It will also make traffic flow more orderly, thus preventing the tragedy of cars all rushing together at intersections.

However, at this moment, the Minister of the Court of Judicial Review stepped forward and said:

“Your Highness, the location at the intersection does make their journey more orderly. However, there is a problem: when they travel on the same road, they will encounter each other head-on. Sometimes they try to avoid each other, but there are times when they cannot avoid each other in time. This situation can easily lead to serious disasters.”

Zhu Yunwen smiled and said:

"Then let's set another rule: no matter what road you're on, you have to keep to the right when riding a bicycle."

This simple sentence immediately amazed the officials, because as long as everyone followed this rule and drove on the right, it seemed to effectively divide the road into left and right sides.

Moreover, they will all go in their own directions, so it is unlikely that they will collide head-on with oncoming vehicles.

The Left Censor-in-Chief of the Procuratorate said with utmost admiration:

"His Highness the Crown Prince's words are simply astounding. Such a simple rule can prevent so much trouble. You have to admire it."

Other officials also spoke up, their admiration for Zhu Yunwen growing ever stronger, as he was able to resolve the frequent bicycle accidents with just a few words.

Moreover, it is quite reasonable, which is amazing.

Zhu Yunwen continued:

"Based on the above rules, it is estimated that another regulation will need to be formulated, namely, that the speed of riding a bicycle on the roads within the city should not be too fast."

If the speed is too high, law enforcement officers at all levels have the right to punish those who ride fast.

The fine ranged from five to one hundred coins. Within this range, the penalty depended on the speed and level of danger while riding. All fines were to be turned over to the Ministry of Revenue!