Increasing a city's traffic capacity by increasing road supply reduces traffic jams and decreases congestion. However, both domestic and foreign experience tells us that simply relying on increasing road transportation facilities does not fundamentally solve the problem of traffic congestion. At the same time, the United States of America's transportation research scholar Dangs pointed out that the construction of new road facilities can reduce the time consumption of travel, but at the same time will attract other roads as well as other modes of traffic to the transfer of the new road, after a period of time, the traffic congestion on the newly built roads will be restored to its original condition. In general, the construction of a new road will not change the original level of congestion, and the induced traffic will quickly occupy the additional roadway facilities. The induced traffic is potential traffic that was not realized due to previous constraints imposed by the level of road supply. Therefore, simply relying on additional road traffic facilities will not solve the problem of traffic congestion at its root.

(2) Imposition of congestion charge

"When there is an externality problem, relying on the market cannot solve the damage, and free competition is unlikely to maximize welfare", in which case the government needs to intervene in the market by adopting appropriate encouraging and restricting economic policies to overcome the marginal individual cost and the marginal social cost deviations. Specifically applied to the problem of traffic congestion, it is to directly tax the traveler who implements traffic congestion, and add the external marginal cost MC× caused by the negative externality to the traveler's marginal personal cost MCP through taxation, and the traveler's cost of travel after taxation MCP'=MCP+MCX=MCS (marginal social cost), so in the individual utility maximization MCS=MRS=MRP, the traveler will automatically reduce the traffic volume from Q2 to Q1 in his personal interest to reach the optimal traffic volume, thus limiting the externality problem through taxation. Similarly, on the other hand, the government subsidizes the non-travelers, i.e., the victims of congestion, according to the amount of elimination of the externality 02 a Q1, which is equivalent to the externality, and encourages them to increase their number from Q1 to Q2

Currently, many countries such as the United Kingdom and Singapore limit the demand for vehicles by charging motorists high congestion fees or parking fees on key road sections to reduce the number of vehicles in the roads. number of vehicles to improve traffic. London in order to solve the traffic congestion in the streets of the capital, decided to reduce the Sunday driving vehicles by 15 %, and plans to start from January 2003, to those who drive into the center of London to charge a fee of 5 pounds. Singapore was the first country in the world to set up an Electronic Road Pricing System (ERP) in September 1998 for urban areas. The ERP system has now replaced the Area Licence System (ALS), which was introduced in 1975, and the Road Pricing System (RPS), which was introduced on three major highways in the early 1990s. In Orlando, Florida, prior to 1994, daily rush hour traffic jams at the Holland East Toll Plaza on State Road 408 often stretched for a mile or more. However, since the introduction of electronic tolling in 1994, travelers have been able to pay without stopping their trips, and throughput has increased from 3,400 to 7,800 vehicles per hour.

(3) Other measures

1. Staggered commute times. By spreading the demand through time can also ease traffic pressure and improve traffic efficiency. Staggered commuting time is more ideal, but due to the life and work habits, the operation has a great deal of difficulty, most of the industry is not very suitable, and therefore its role in easing traffic pressure is limited, and not necessarily achieve maximum economic efficiency.

2, give priority to the development of public **** transportation. The implementation of public **** traffic most in line with the urban transportation as a public **** product of the intention, but also a practical measure to reduce traffic congestion, reduce environmental pollution, save resources in many ways, but it is not conducive to the development of a country's automobile industry. And for individuals, the car is always more comfortable than the bus, convenient, more reflect the identity and status of the individual, so with the increase in income level, people have the desire to own their own car.

3, the intelligent transportation system is an ideal mode of traffic demand management, it can not only alleviate and eliminate traffic congestion, but also maximize the use of existing roads, so as to achieve maximum economic efficiency; but in practice, most of the cities in most countries do not yet have such high technology. As a result, for most of the current city, can only stay in the traditional line and parking demand control. Conclusion

Through the economic analysis of traffic congestion and countermeasures research shows that increasing the road supply is necessary, but a single increase in the supply of roads can not solve all the problems, not to mention that increasing the supply of roads is subject to land constraints, but also cost a lot of money to repair the roads. Therefore, a more effective way to solve traffic congestion is to traffic demand management. In the traffic demand management, various methods have their advantages and disadvantages, a single method can not solve the problem of congestion. We should see that the causes of traffic congestion are manifold, the construction of qualified roads, improve the efficiency of the use of roads is the key to traffic congestion, but the main reason for the congestion also lies in the inadequacy of urban planning. Inadequate urban planning has resulted in too many people and too few cars, too many cars and too few roads, and the traffic arteries cannot form a reasonable network, making the roads unable to give full play to their roles. The implementation of congested road pricing will be a major measure to ease traffic congestion, but it needs to be carefully studied. In fact, since the introduction of the concept of "congestion pricing" to the present, there have been numerous controversies in various cities and even the country. A set of data analysis shows that the reason why London has implemented this measure and achieved success, there are objective reasons for it: in increasing road capacity at the same time, London is not only vigorously develop public **** transportation, including 3730 km of bus lines, 329 km of the subway, the light rail 28 kilometers, 788 kilometers of railroads; about 8,500 buses, 700 operating lines, many lines 24 hours a day operations, but also Efforts have been made to improve traffic management, with a high level of informationization and intelligent management. It was after all these efforts had been made and the traffic situation was still unsatisfactory that the decision was made to introduce a "congestion charge" to improve traffic.

China is the world's most populous country, once the income of urban residents to raise to the level of generally able to buy a car, China's traffic congestion problem will be more serious. Taking Beijing as an example, the number of cars in Beijing is increasing rapidly at a rate of 1,000 per day, and Beijing's environment and transportation are still facing great difficulties. Therefore, the government has accelerated the construction and improvement of the public **** transportation network with rail transit as the skeleton, optimized the layout of the bus network, done a good job in the interchange and connection of public **** transportation, and encouraged the development of bicycle rental services in order to build a people-oriented public **** transportation system. On this basis, and then through the development of economic policies, including parking fees, license fees, including the alleviation of traffic pressure. Whereas administrative policies such as single- and double-number restrictions and staggered commuting limit people's travel choices and make it difficult to implement them in the long term, economic policies achieve the effect of managing traffic demand by using economic levers to make roads, transportation facilities, parking spaces, and other limited resources reasonably allocated and regulated.