1. 1 There are serious traffic jams and frequent traffic accidents.
Restricted by the early topographic conditions, the built-up area of Lanzhou four districts is dumbbell-shaped, and the central city is located at the narrowest place. The road network structure is unreasonable and the branches are not smooth, especially in the areas of Jiefangmen, Xiguan Cross and Zhongshan Road, which are like natural traffic bottlenecks, making the urban traffic in Lanzhou, which is dominated by plane mixed traffic, chaotic. Traffic conflicts between cars and people have become an important factor in traffic congestion. Some traffic participants have a weak legal concept and traffic violations are very serious. Urban traffic accidents have caused a large number of casualties and high economic losses. According to statistics, in recent years, there are about 600 road traffic accidents in Lanzhou every year, resulting in nearly 1 10,000 casualties and direct property losses exceeding10.5 million yuan. The occurrence of traffic accidents has brought serious economic and social losses to many families and the whole society.
1.2 environmental pollution is serious.
Lanzhou's unique geographical environment and industrial structure make it a city with serious air pollution. In recent years, while the number of urban motor vehicles has increased, it has brought noise pollution. According to relevant departments, road noise is the first major hazard of noise pollution in Lanzhou. Lanzhou city is narrow and the roads are relatively dense. The annual growth rate of passing vehicles reached 20%, and the daytime noise of several main roads such as Baiyin Road and Binhe Road reached 70.2 decibels. With the increase of traffic noise, the emissions of carbon monoxide, hydrocarbons, carbon dioxide, nitrogen oxides, lead compounds and other automobile exhaust gases are gradually increasing. The resulting vibration and electromagnetic waves seriously endanger people's physical and mental health and affect people's normal life and study.
1.3 The contradiction between supply and demand is prominent.
1.3. 1 contradiction between vehicle supply and demand
In the wave of western development, the total population of Lanzhou has expanded rapidly in recent ten years, resulting in very serious traffic congestion. The current Code for Planning and Design of Urban Road Traffic (GB50220- 95) stipulates that the number of public transport vehicles in big cities is not less than 800- 1 1,000 people (equivalent to 10- 12. 5 standard cars per 10,000 people), which should be 1, 200-650 in small and medium-sized cities.
N = P X M [ 1]
Where: n is the development scale of urban public transport (standard public transport);
P-urban population (ten thousand people);
M- Bus ownership rate (standard car per 10,000 people).
The number of urban taxis is calculated according to the following formula [2]:
[2]
Where is the total effective mileage of city taxis;
Is the idle driving rate;
Is the average operating speed of taxis (km/h);
According to the formula [1], there should be 3 140-3925 standard vehicles in Lanzhou at present, but the number of public transport vehicles in Lanzhou is far from this standard. According to formula [2], the total number of taxis in Lanzhou should be maintained at 6,538 at present, but there are only 4,889 taxis in operation, which is far below the national standard. In addition, taxis operate with even and odd numbers. Except holidays, there are less than 2,500 vehicles actually operating every day. Relevant statistics show that at present, the peak passenger flow of one lane in traffic-intensive areas such as Baiyin Road in Lanzhou City has reached 6.5438+0.9 million passengers per hour, while the maximum transport capacity of conventional public transport is 0.3 million to 6.5438+0 million passengers per hour, and the maximum transport capacity of urban rapid transit system is 20,000 passengers per hour. In some key traffic areas, the existing conventional buses have reached the bearing limit.
1.3.2 contradiction between road supply and demand
According to the data of Lanzhou Statistical Yearbook, during the period of 10, the road mileage of the whole city increased by less than 30%, while the number of motor vehicles increased at the rate of 18.6% every year, forming a fault-like disparity. It makes the road traffic in Lanzhou city more crowded. The speed of urban motor vehicles drops sharply, which directly leads to the decline of public transport service level, the lag of roads and traffic management facilities, and the serious shortage of static traffic facilities such as parking lots.
1.4 The urban road network layout and traffic structure are not reasonable.
In the overall layout of urban traffic development, due to the lack of traffic impact assessment and planning, it is difficult to heal, the land use and traffic mode are not unified, the traffic connection between functional areas is inconvenient and unblocked, the traffic flow is highly concentrated in time and space, the proportion of primary and secondary roads and branches is unbalanced, and the weak secondary roads and branches are difficult to undertake the function of vehicle relief and diversion, which makes most of the traffic flow gather on the main road. At the same time, the secondary roads and branches lack systematic connection, so it is impossible to form a perfect network and divert traffic between regions. Affected by subjective and objective factors such as special topography and planning, the layout of urban bus hub stations and long-distance passenger stations is unreasonable, the construction of bus stations is insufficient, the transfer system is imperfect, the line setting is too long and repetitive, the traffic facilities such as overpasses and parking berths are insufficient, and a large number of people and vehicles are concentrated, which leads to the continuous aggravation of road traffic congestion. From the perspective of transportation structure, the number of buses and taxis per 10,000 people has not reached the national standard, and all kinds of vehicles are seriously mixed.
2. The necessity of sustainable development of urban traffic
2. 1 The urban development area is limited and the transportation infrastructure is relatively weak.
Lanzhou is 50 kilometers long from east to west and 3 kilometers wide from north to south. It is a typical "two mountains and one river" terrain. As a city with an inch of land and gold, urban land is extremely limited. In the past, the urban planning was adapted to local conditions, which caused the urban structure of Lanzhou to be too compact, the population living and urban functions to be too concentrated, resulting in the total urban traffic demand exceeding the upper limit of urban traffic carrying capacity, and the land use intensity of urban central business district was too large to solve the urban traffic problem. According to statistics, at present, the total road area in Lanzhou is 6.5438+0057 million square meters, the per capita urban road occupancy rate is only 6.67 square meters, the road network density is 4.74 kilometers per square kilometer, and the sum of the proportion of public transport and shuttle bus is 654.38+09.58%. The density of bus stops is 6.44/km2, and the density uniformity of bus stops is 0.475, both of which fail to reach the lower limit of national planning index.
2.2 Urban ecological environment is deteriorating.
In recent years, with the rapid increase of the number of motor vehicles in cities, automobiles have become the main pollution source of urban environment. 40% ~ 90% of the main urban waste gas comes from automobile exhaust, traffic noise pollution, oil leakage and tire rubber crumbs pollution to surface water. Due to the poor ecological environment in the west, the total vegetation area and per capita greening rate in Lanzhou city have not reached the lower limit of national standards, and the suspended solids such as dust in the air are obviously higher than those in the eastern cities [3]. Therefore, it is more urgent to control the pollution caused by urban traffic development.
3. Obstacles to the sustainable development of urban traffic in Lanzhou
Generally speaking, the sustainable development of urban traffic in Lanzhou faces four obstacles:
3. 1 does not correctly handle the relationship between urban planning and traffic planning.
Traffic planning has always been in a subordinate position to adapt to the changes of urban planning, and there is no interactive feedback mechanism between them. The traditional urban traffic development model is in the form of "increasing traffic demand-increasing traffic supply-increasing traffic demand". This model can not get rid of the vicious circle of "crowding-loosening-re-crowding" [4].
3.2 For some time, the dominant idea of urban transportation planning has deviated.
For a period of time, urban transportation planning has emphasized the supply of transportation, ignoring the demand and management of transportation [5]. The dominant idea of urban traffic planning overemphasizes the accessibility of traffic, without considering the time cost and expense cost of traffic and the traffic environmental capacity of urban roads.
3.3 Urban traffic construction and management departments are too many, resulting in management confusion. Due to the inconsistent interests of various government departments, the policies formulated by various departments lack unity. In particular, the traffic construction inside the city is not in harmony with the highway construction outside the city, and there is no good connection from planning, construction to maintenance management, which makes the suburban junction a traffic bottleneck.
4. Strategies to solve the sustainable development of urban traffic in Lanzhou.
The new traffic concept produced by the historical experience of urban traffic development at home and abroad has reference and guiding significance for the later development of Lanzhou urban traffic. Under the natural and social background of Lanzhou, two principles are mainly considered when formulating the traffic development strategy. On the one hand, it is necessary to ensure that the traffic development in Lanzhou can meet the needs of social and economic development; On the other hand, it is necessary to ensure that the planning of the transportation system is moderately advanced and has forward-looking guidance for social and economic development. The author thinks that we should think from the following angles.
4. 1 transportation system positioning for the sustainable development of urban traffic in the narrow valley: road network system to ensure smooth roads and traffic management system to respond quickly to urban traffic problems.
Downs' Law holds that new road facilities will induce new traffic volume, and the traffic demand always tends to exceed the traffic supply, so no matter from the perspective of economy or resources, the traffic supply is always time-limited, and the traffic demand is expansive, so it is actually impossible to achieve the absolute balance between traffic supply and demand [6]. Lanzhou belongs to a relatively large-scale city, and its urbanization development continues to expand outward in a single-center mode. It is easy to form the situation that the city develops too fast and the city scale expands extremely, which leads to the shortage of urban transportation land and the rapid imbalance between transportation supply and demand. In terms of urban traffic development, we should consider the present situation and future development of the city, which not only serves the current urban economic transformation, but also provides certain guidance and guarantee for the urban development after the transformation.
4.2 Bus priority is a shortcut to solve the problem of sustainable development of Lanzhou traffic.
Combined with the terrain characteristics of Lanzhou, the bus solution mode focuses on BRT and BRT one by one, forming an urban traffic network system combining the backbone traffic network of 2-3 expressways with the community bus network based on backbone traffic network sites. Taking "bus priority" as the basic principle of urban transportation development, the author thinks that Lanzhou should establish an urban public transportation system suitable for Lanzhou's urban terrain characteristics. Establish large-capacity, dedicated and fast bus lines such as rail transit, improve travel time between residential areas and improve the combination of residence and work. The construction of east-west rail transit, supplemented by the normal bus in the north-south direction perpendicular to it, will greatly alleviate the current situation of east-west congestion and poor north-south direction.
4.3 Avoid the formation of main roads of life and ease the restriction of traffic capacity.
However, due to the shortage of urban land, it is impossible to provide a large number of traffic land. Therefore, Lanzhou has a living traffic trunk road, such as Xijin East Road. When the two kinds of traffic flows are completely opposite in nature, it will be difficult for road space to integrate them into an orderly traffic flow, such as transit traffic and shopping traffic. Therefore, in the setting of road functions, especially in urban traffic bottlenecks, living trunk roads should be avoided.
4.4 Solve the problem of sustainable development of urban traffic in Lanzhou from a regional perspective.
Interception and diversion of mixed traffic in valley cities is the key to realize smooth urban traffic. Separate mixed traffic in space and time [7]. That is, from the perspective of time, using the imbalance of different traffic flows, stagger the peak hours of passenger and cargo transportation, labor study and leisure tourism, win space with time and alleviate urban traffic congestion; In terms of space, urban traffic is divided into urban space and regional space. On the one hand, various measures are taken to straighten out the spatial structure within the city and alleviate the traffic contradictions within the city. On the other hand, the improvement and rationalization of the transportation system in the peripheral areas of the city can also reduce the transit traffic volume and reduce the traffic pressure of the road system in the city.
4.5 Form scientific modern traffic management.
Combining high technology with management innovation, scientific and efficient traffic management can give full play to the potential of existing traffic facilities, improve the existing traffic order, alleviate traffic congestion, reduce traffic environmental pollution and traffic accidents, and improve the efficiency of the whole traffic system [8]. At present, Intelligent Traffic Management System (ITS), Global Positioning System (GPS) and Geographic Information System (GIS) have been applied. Intelligent transportation system will be the mainstream of traffic development in 2 1 century, which can improve the utilization rate of existing roads 15%-30%. The research in recent 20 years shows that the implementation of ITS can improve the road capacity by 2-3 times and increase the vehicle capacity.
4.6 Improve the use efficiency of existing traffic facilities.
In the case that the supply of urban traffic facilities cannot be increased indefinitely, western countries generally improve the utilization efficiency of traffic facilities by improving urban traffic management, so as to maximize the utility of existing traffic facilities. Looking at the practice of traffic management at home and abroad, the main measures to improve urban traffic management include: intersection signal control; Channelization of imports, setting up special lanes and optimizing out-of-control resources at traffic intersections; At signal timing, release as many vehicles as possible within the effective green time to control node traffic; Set up one-way traffic lanes, public traffic lanes, truck lanes, bicycle lanes, "green wave" traffic lanes and special traffic lanes to control node traffic.
4.7 Relieve the population in the central city of Lanzhou and adjust the land use function.
The special terrain of Lanzhou City makes the traffic network of Lanzhou City form many beehives, which will greatly restrict the economic development of Lanzhou City. Using the land gradient effect, factories, warehouses and land that are not suitable for the function of the city center will be moved to the peripheral areas of the city, and the activities of the city will be appropriately dispersed to find a new balance from the total traffic volume and promote the formation of a reasonable traffic structure.
4.8 Implementation of congestion charges.
Congestion charging is to control the travel demand, adjust the travel path, reduce the traffic flow of roads in congested areas and relieve traffic tension by charging certain fees to road users in some areas when traffic is congested. The concept of "congestion charge" appeared in the 1970s, and now it has been gradually valued and applied. In Lanzhou, a belt-shaped city limited by river valley topography, the urban land area is very limited, so we should consider appropriately collecting congestion charges to reduce the congestion during peak hours and build a harmonious urban traffic.
4.9 Conduct traffic impact analysis on land development and collect traffic impact fees.
Traffic impact analysis and traffic impact fee policy began in the United States and have been widely used in Canada, Australia, Western Europe and Japan [9]. Traffic impact analysis is to study the relationship between urban development projects and traffic demand growth, analyze the extent and scope of the impact of projects on urban traffic service level, and then determine the countermeasures or transformation schemes to keep the traffic service level from declining, so as to reduce the impact of development schemes on traffic load. On the basis of traffic analysis, the traffic impact fee policy is formulated, and the prescribed traffic service level is maintained by forcibly charging developers for improving traffic infrastructure, so that land use developers can bear direct economic responsibility for the traffic and environmental impact caused by their development activities. In this way, it will be more conducive to achieving the long-term goal of sustainable development of urban transportation in Lanzhou.
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