Trailers are one of the main types of vehicles in the logistics and transportation industry, such as semi-trailers, full trailers, center-axle trailers, etc. At present, semi-trailers are most commonly used in China, which are composed of a tractor and a semi-trailer compartment. With the continuous improvement of vehicle technology, more and more new models are widely used, such as double trailers.
At first glance, this title seems to have a somewhat unclear meaning. Double trailers, whose scientific name is double-trailer trains, continuously tow two standard semi-trailers behind a standard tractor, or tow a standard semi-trailer and a center-axle car. Among them, the rear of a semi-trailer in front has been modified accordingly and is used to tow the semi-trailer or center-axle compartment behind.
After seeing the picture, many people said: Why does this model look so familiar? Isn't this a car that was modified privately before?
Yes, in the early years, the relevant laws and regulations on vehicles were not perfect, and privately modified models were relatively common. Such models similar to double trailers did appear before, but the laws and regulations never recognized their legality, allowing the traffic police to catch them. Yes, fines and points deductions are not negotiable.
It is understood that this kind of double trailer is currently used in many countries. In countries such as Sweden, Finland, the Netherlands, and Spain, the standard connection method is tractor + 13.6-meter standard trailer + trailer connection platform + 13.6-meter standard trailer. The total weight does not exceed 72t, with a total of 11 axles, and the average axle load under full load is about 6.5t. Compared with an ordinary semi-trailer with a total weight of 40t, the average axle load is reduced by about 1.5t.
In contrast, in my country, in recent years, users' pursuit of transportation loading capacity and timeliness has continued to increase, resulting in the frequent appearance of oversized and overlong vehicles in the transportation market, which neither meet regulatory requirements nor achieve standardized management, and are not conducive to driving safety. However, double trailers are subject to the restrictions stipulated in GB1589 that "the maximum allowable total vehicle mass is 49 tons, the maximum total length does not exceed 16.5 meters, and the total length of the car train does not exceed 22 meters", so it has not been applied.
Compared with ordinary trailer models, what are the advantages of double trailers?
1. Compared with ordinary tractor-trailer combinations, the transportation volume of double trailers can be increased by 50%, and the transportation unit cost of various comprehensive cargo combinations can be reduced by about 34% on average, greatly improving transportation efficiency;
2. By using the double trailer transportation mode, road transportation can reduce the unit fuel consumption of transported goods by 10%, while also reducing transportation costs and releasing road space to a certain extent;
3. In addition to commercial benefits, double trailers also bring significant environmental and social benefits, which can help reduce carbon dioxide emissions, reduce road surface wear, and alleviate driver shortages.
Although double trailers have obvious advantages in transportation, they also have many shortcomings:
1. It goes without saying that the additional danger brought by excessive total mass is that the vehicle body is too long and heavy, making driving more difficult, and its lethality cannot be underestimated. It is also because of this that vehicles participating in double-trailer transportation abroad must be equipped with hydraulic retarder, full vehicle air suspension, disc brakes, and must be equipped with complete mechanical and electronic auxiliary systems, such as blind spot monitoring, adaptive cruise, Electronic stability system, etc.
2. Transportation roads are restricted. After all, most highway entrances and exits, roundabouts, curves, etc. cannot meet the transportation needs of double trailers, and the vehicles may face difficulty in turning. In addition, many service areas or gas stations cannot provide overly long parking spaces. If you want to park a double trailer, you may have to unhook it and park it separately, which affects transportation efficiency.
3. Driving difficulty is too high. Compared with ordinary semi-trailers, it is more difficult to drive a double trailer. Therefore, the requirements for double trailer drivers abroad are also very strict. They must have 5 years of truck driving experience and no driving experience for 3 consecutive years. In the event of an accident, you must receive training before driving. In addition, when driving a double trailer, it is required to prohibit overtaking at all times, and it is prohibited to drive in harsh environments such as heavy rain and snow. The length of the vehicle must be marked on the rear of the vehicle, and reflective strips and warning signs must be installed.
However, according to industry insiders, the dual-trailer plan to implement demonstration applications in some areas of the country during the "14th Five-Year Plan" is mainly due to four considerations:
1. The volume of road transportation is large and the task of energy conservation and emission reduction is heavy. At present, the freight volume of road transportation accounts for more than 70% of the comprehensive transportation system. Coupled with the continued development of the express delivery industry, the demand for large-volume transportation models is growing day by day. In addition, the pressure for energy conservation and emission reduction is huge, and there is a long way to go to achieve the “double carbon” goal;
2. Non-standard models will be eliminated, and replacement models are in urgent need of supplementation. At present, relevant departments are increasingly strengthening the management of non-standard vehicle models, and the transportation industry is in urgent need of supplementing alternative models to alleviate the industry's actual demand for large-capacity transportation;
3. The international technology and experience in using double trailers is rich enough, providing a good reference experience and learning basis for domestic research;
4. Our country has now become a party to the United Nations Customs Convention on the International Transport of Goods under TIR Carnets. While promoting the facilitation of international road transportation in our country, it has also promoted the integration of domestic models with international models. It is urgent to improve the types of road transport vehicles in our country.
It can be seen that it will take some time for double trailers to be used in China. Perhaps they will become legal models on the road in the near future. Based on relevant foreign experience, double trailers may be equipped with disc brakes and air suspension as standard equipment.