On this day 39 years ago, on February 12, 1986 (January 4, 1986 lunar calendar), the Channel Tunnel Treaty between Britain and France was officially signed. French President François Mitterrand and British Prime Minister Margaret Thatcher exchanged the text of the Channel Tunnel Treaty between Britain and France. On February 12, 1986, British Prime Minister Margaret Thatcher and French President François Mitterrand attended the signing ceremony of the Channel Tunnel Treaty between Britain and France at Canterbury Cathedral in the southeast of England, thus formally confirming the commitment of the two governments to the construction of the Channel Tunnel project. Because the French constitution stipulates that the president cannot sign foreign treaties, the treaty was signed on the same day by British Foreign Secretary Geoffrey Howe and French Foreign Relations Minister Laurent Dumas. At the signing ceremony, Mrs. Thatcher said that the treaty wrote a new chapter in the industrial cooperation between Britain and France, and was also an important event for the whole of Europe. President Mitterrand pointed out that the treaty is an important milestone in the history of relations between the two peoples. Britain's connection with the European continent has been mainly through the English Channel since ancient times. The transportation between the channels is extremely frequent. Take 1984 as an example, there were 20 million round-trip passengers and 20 million tons of freight. Such busy exchanges make people feel more and more that it is imperative to solve the problem of channel transportation. As early as 1751, the French scholar Nicola Demare wrote a "Theory of the Ancient British-French Border", explaining that the land of Britain and France in ancient times was connected. In 1802, the French engineer Mathieu proposed to Napoleon I to build an undersea tunnel directly to the United Kingdom, but it was rejected. Since then, many people have put forward various proposals to dig the Channel Tunnel between Britain and France. The development of modern European economy once again brought this tunnel project to the forefront of the people. In November 1973, the British and French governments signed a treaty on the construction of the undersea tunnel, and put forward specific plans. In 1978, the state-run railway companies of the two countries resumed the study of the tunnel plan. In November 1984, British Prime Minister Margaret Thatcher reached a basic agreement with French President François Mitterrand. In May 1985, the two governments invited major engineering companies and bank consortiums from various countries to submit draft engineering plans. The proposal selected by the French and British leaders was proposed by the Anglo-French Channel Tunnel Consortium. According to the preliminary design of the plan, between Dover and Calais at the narrowest point of the channel, in the chalk rock at a depth of 40 meters below the sea floor, two railway tunnels with a diameter of more than 50 kilometers and a diameter of 7.3 meters are dug, of which 37 kilometers are under the sea. One is for the Paris-London train traffic, and the other is for the shuttle train operation, which is dedicated to transporting people and their vehicles crossing the channel by car. In the central axis of the two main tunnels, another service tunnel with a diameter of 4.5 meters is opened, which is connected with the main tunnel every 375 meters to solve ventilation and maintenance problems. The total cost of the project is expected to be about 53 billion francs. Neither government provides public funds, but all use private capital to build. The two governments also tasked the Anglo-French Straits Consortium, which is made up of 15 companies and banks from the two countries, to come up with a plan to build another fixed road corridor within 15 years. After the completion of the Channel Tunnel in 1993, it took only 26 minutes for high-speed trains to pass through the strait. It operates all day, and a train can leave every 3 minutes during peak hours, and it can carry 4,000 cars to each side of the strait every hour. The annual passenger volume of the two tunnels is 40 million, and the freight volume is 13 million tons. According to statistics, in 1983, the passenger volume of the strait was 24 million, and the freight volume was 26 million tons.