Urban road traffic management planning is the premise and foundation of urban sustainable development. This paper analyzes and introduces the present situation of urban road traffic management planning in China, expounds the purpose, content, level and process of traffic management planning, and probes into the analysis method of traffic demand prediction and the application of corresponding traffic demand model in traffic management planning.
Keywords: urban road traffic management planning traffic demand
1. Current situation of road traffic management planning
The development of urban transportation system in western countries has gone through two stages, namely, the construction stage: from World War II to 1970s; Management stage: 80' s to present. Focus on the traffic management planning of public transport system, car development, single traffic, traffic signal control and effective use of roads.
At present, the development of urban traffic in China is equivalent to that of western countries in the 1960s and 1970s. Compared with developed countries, the density of urban motor vehicles is still low. Nevertheless, the environmental pollution and urban traffic congestion caused by motor vehicles are also very serious. This fully shows that there are still problems in system, administration and technology in road traffic management in China.
With the in-depth development of the national urban road traffic unblocked project, the traffic conditions in many cities have been greatly improved, and a series of advanced traffic management equipment and advanced management models have been adopted, and good results have been achieved. Such as Xiamen, Dalian, Nanjing, Qingdao, Jinan, Hangzhou and other cities, traffic management work is very effective, was rated as "excellent management level" of the smooth project.
At the same time, we should clearly realize that there is still a certain gap between the overall level of urban traffic management in China and the requirements of unblocked projects. In 2000, among the 138 cities inspected by the national "unblocked project" working group, the traffic management planning of 42 cities only met five requirements of 1 1 unblocked project, and 20 cities only met four requirements. It can be seen that China's urban traffic management planning lags far behind the requirements of modern road traffic development.
The urban network is very complicated, the traffic operation is very complicated, and the factors that cause traffic problems are also very complicated. The corresponding urban traffic management scheme is often composed of various management strategies and measures. The implementation of any construction or management measures will cause changes in the traffic operation of the whole urban road network. For example, a road section is changed to one-way traffic or even-numbered traffic, the intersection type is changed (no control is changed to signal control), a road section is changed to bus lane, a road is opened or a road is widened. The traffic flow and speed of the main roads in the city will change by more than 80% ~ 90%. Therefore, the traffic management problem is a systematic project, which must be solved by scientific methods, and ordinary empirical methods cannot be completely solved. Therefore, traffic management needs planning. In fact, some management measures implemented in some cities are planned, but they are not systematic and comprehensive.
In order to change the backward situation of urban traffic management planning, Harbin Institute of Technology, Tsinghua University, Tongji University, Southeast University and other universities, as well as the Institute of Traffic Science of the Ministry of Public Security, China Urban Planning and Design Institute and other departments are committed to the preparation of road traffic planning in some cities, which has made due contributions to improving the level of road traffic management in China.
2. The basic contents and methods of road traffic management planning.
2. 1 The purpose of road traffic management planning
The purpose of road traffic management planning is to solve the problems of whether to manage, when to manage, how to manage and where to manage. Through planning, people can know the effect of management strategy in advance and avoid the policy imbalance and huge economic losses caused by blind management.
2.2 The basic content of road traffic management planning
The work contents of road traffic management planning mainly include:
(1) Investigation of Urban Road Traffic Status
The data to be investigated and collected include: traffic community division and community economy, land use data, traffic network structure and road geometric characteristics data, historical road traffic volume and flow direction data, residents' travel characteristics data, motor vehicle travel characteristics data, goods travel characteristics data, existing traffic management facilities and effect data, etc. In this respect, due to the extensive traffic survey, heavy investigation workload and large capital investment, some urban traffic planning units and even leaders of relevant government departments pay insufficient attention to the basic data survey, and think that as long as some supplementary surveys are carried out on the basis of the original traffic planning data collection, the planning scheme will be divorced from reality, with poor pertinence and operability. This is an extremely wrong and one-sided view, which should be highly valued by relevant departments.
(2) Present situation analysis and problem diagnosis
From the aspects of road infrastructure, land use and public transportation, traffic management facilities and modernization, traffic order, traffic quality and safety, traffic management system, policy, planning and publicity and education, this paper analyzes and diagnoses the present situation of urban road traffic and management.
(3) Analysis of urban traffic demand
Through the establishment and calculation of traffic demand model (the specific model and method will be discussed in the next section), the od matrix of each vehicle type (bus, motorcycle, bus, taxi, van, bicycle) in the implementation (evaluation) year of traffic management planning scheme is obtained, which provides planning basis and parameters for later traffic planning.
(4) Formulate the urban traffic management plan.
A city's traffic management scheme often consists of a variety of management strategies and several management measures. Generally, it includes traffic demand management strategies, such as priority development strategy, restricted development strategy, no travel strategy and economic leverage strategy; Traffic system management strategies, such as node traffic management, trunk traffic management and regional traffic management.
(5) Evaluation of urban traffic management scheme
Through scheme evaluation, this paper analyzes the influence of traffic management measures on traffic flow, predicts the traffic operation indicators under the implementation of traffic management measures, and analyzes whether the management objectives are achieved.
The evaluation of traffic management scheme can be divided into four steps: road network abstraction, traffic management scheme abstraction, traffic flow redistribution simulation and management effect analysis.
3. Establishment and development forecast of traffic demand model.
Traffic demand forecasting is the basis of urban road traffic management planning. To do a good job in traffic management planning of a city, we must first make a quantitative forecast of travel and analyze and demonstrate a certain traffic facility or system. The traffic capacity of each road section, intersection and the whole road network must meet the traffic demand of current, short-term or long-term travel. Therefore, only by making a good traffic forecast can we know whether the road network can meet the travel demand of the city and improve it accordingly.
3. 1 Travel generation forecast
The purpose of residents' travel forecast is to establish the quantitative relationship between residents' travel volume and attractiveness and variables such as community land use and socio-economic characteristics, and to calculate the travel volume and attractiveness of residents in various transportation communities in the planning year. Trip generation includes trip occurrence and trip attraction. There are many methods to predict residents' trips, such as cross classification, regression analysis, generation rate method, attraction rate method, average trip times method and so on.
The prediction of residents' trip distribution is a process of transforming the predicted trip occurrence and attraction of each partition into the trip exchange between future traffic partitions. Prediction methods can be roughly divided into three categories, namely, growth rate method, probability model method and gravity model method. Among them, the double constrained gravity model method is the most widely used in transportation planning at home and abroad.
3.2 Traffic Distribution Forecast
Knowing the travel generation, travel attraction and travel distribution of each partition, that is, knowing how big the travel exchange capacity between each partition is, you can start traffic allocation. Traffic assignment is to assign O-D space between partitions to a specific traffic network. The traffic volume data of road sections and intersections obtained through traffic assignment is one of the main bases to test whether the road planning network is reasonable. At present, stochastic user equilibrium model is widely used in road traffic management planning. The model establishes the functional relationship between road travel time and road traffic volume, and considers the limitation of traffic capacity. Through repeated iterative calculation, until the required accuracy is reached, the traffic volume of each road section is finally allocated.
3.3 Parking demand forecast
Many big cities in the world have conducted in-depth research on parking demand forecasting. Due to different national conditions, different urban development models, different economic growth and different parking prediction models, their calculation methods are also quite different. Commonly used forecasting models include: parking generation rate model, land use and traffic impact analysis model, correlation analysis model, motor vehicle OD prediction model, traffic volume-parking demand model and static traffic generation rate model. Here is a brief introduction to the widely used static traffic incidence model and traffic volume-parking demand model.
(1) static traffic event model
According to the parking survey data, we can get the number of parking in each traffic district every day, and then convert it into standard cars according to the proportion of parking vehicles. Using the present situation of social economy and land use in comprehensive transportation planning and the number of employed people in the near and long-term planning years, we can take some samples and establish a static traffic incidence model:
Pij=∑aiLij (i= 1，…，m j= 1，…，n) ( 1)
Where: Pij is the basic daily parking demand (standard trip/day) of the traffic community in the J year of the forecast year; Ai refers to the static traffic occurrence rate of Class I land (standard trips/100 operations/day); Li Ji is to predict the number of people employed in Class I land in J traffic community in (person); N is the number of cells; M is the land use classification number.
The nonlinear optimization method is used to solve the model, that is, the nonlinear optimization model is established:
The parameters in the formula have the same meanings as before.
(2) Traffic volume-parking demand model
Through the comparison of several parking demand forecasting methods, it can be seen that although the model can not get the parking facilities demand of each land in the region, it is more suitable for the macro parking demand analysis of traffic communities because of its combination with dynamic traffic forecasting methods. Therefore, the model can be used to test the calculation results of static traffic event model.
The model expression is:
logPi = Ao+a 1 logv ki+A2 logv hi(3)
Where: Pi is the daily parking demand of traffic community in the predicted year I (standard trips/day); Vki is the daily travel attraction of passenger cars in the ith traffic community in the forecast year (standard trips/day); Vhi is the daily travel attraction of trucks in the ith traffic community in the forecast year (standard trips/day); A0, A 1 and A2 are regression coefficients.
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