Problems and methods that should be paid attention to in highway route design?

Highway construction is conducive to regional economic development, improving the quality of social development of

Problems and methods that should be paid attention to in highway route design?

Highway construction is conducive to regional economic development, improving the quality of social development of residents along the route, providing people with fast transportation and other advantages, and has good development prospects. Based on the actual situation in expressway, this paper analyzes and discusses the route design of expressway, so as to make the design of expressway better!

Highway route design; Security; Reliability; There is a problem; Coping method

Highway alignment design is the core of highway design, and its design should ensure the safety and comfort of vehicles, the driver's visual and psychological reaction, guide the driver's line of sight, maintain the continuity of alignment, and make the driver feel comfortable and safe enough. The quality of highway alignment directly affects the safety, economy, comfort and speed of highway operation. At present, China's highway route design adopts the standard values of highway alignment design at all levels specified by China people and national industry standard jtg d20-2006 "Code for Highway Route Design" and jtg b0 1-2003 "Technical Standards for Highway Engineering", and adopts the minimum design standards specified by design parameters based on design speed, and other design indexes are determined accordingly according to design speed. It is a challenge for researchers and designers to improve the road transport capacity and service level, realize the optimal economy of linear design, and establish a reasonable, scientific and perfect evaluation method for comparison and selection of highway route design schemes.

Highway route alignment is the most critical step in highway design, because route alignment is the skeleton of highway. Whether the alignment is reasonable or not will directly affect the design of highway bridges, tunnels, artificial structures, subgrade and pavement, and it is also the main factor to control the project cost. At the same time, after the completion of expressway, it is generally difficult to change the route. Especially the route of high-grade highway, once completed, will restrict the economic and social benefits of highway for a long time. Therefore, some countries put forward that the road route is the life of the road, which plays a decisive role and influence on the comfort, safety, economy and road capacity of the car.

1 highway alignment design

1 vertical line modeling standard is not high. It is good that most of the plane alignment design standards of new highways adopt the upper limit, and its advantages have been fully confirmed in the process of highway reconstruction and expansion. On the contrary, the design of longitudinal broken line is almost completely controlled by excavation, which leads to the design radius of longitudinal broken line is small and the vertical curve is short. It is suggested that the comprehensive service level of highway should be considered in the future alignment design, and the longitudinal alignment standard should be raised appropriately. Do a reasonable combination of horizontal, vertical and horizontal.

In the design of reconstruction and expansion projects, it is often limited by the idea of using old roads to reduce land occupation, which leads to the low standard of plane alignment and the idea of scheme comparison, which may lead to the failure of a good scheme. If we get rid of the thinking limitation of using the old road, the new line can improve the new shape index and shorten the plane distance after straightening. Therefore, it is suggested that the plane alignment standard of new highway should be determined from the viewpoint of development, and the design idea of old road reconstruction project should try to get rid of the limitation of using old road.

The land occupation provided by the previous design documents is basically accurate, which provides a basis for the early demolition of the project management department. However, some design documents provide inaccurate or insufficient land, which also brings great trouble to the project management department. I hope to pay more attention to it in the future design.

2 principles of highway route design

2. 1 quality-oriented principle

A century-long plan, quality-oriented. Highway route design should be carried out in strict accordance with the current norms and standards, and the quality of design is directly related to the quality and effect of subsequent construction. The linear design in plain area belongs to conventional design, and the design quality can be grasped according to conventional design specifications. The alignment in mountainous areas is more complicated than that in plain areas. In addition to controlling the quality of conventional design, attention should also be paid to plane alignment, superelevation setting, longitudinal alignment design, climbing lane and sight distance.

2.2 the principle of combining the whole with the region

Generally speaking, the direction of the big route has been determined in the road network planning. Therefore, route selection needs to start from the global nature of the road network and feel the direction of one of the roads according to the overall situation of the road network, so as to make the overall road network structure the best and maximize the benefits. At the same time, the route selection of regional roads needs to be further refined, and multiple schemes must be selected.

2.3 Multi-scheme comparison principle

Highway route design often crosses complex terrain. Different sections have different geological conditions, construction conditions and difficulties, especially in mountainous areas. There are many factors to be considered in route design and selection. Comprehensive design requirements, construction conditions and cost, construction period, technology and economy and other factors, choose the best regional scheme.

3 highway route design status, existing problems and solutions

1 The theory of highway route design in foreign developed countries, from simply considering the power requirements of automobiles, gradually pays attention to the physiological and psychological characteristics of drivers, advocates the people-oriented design concept, pays attention to the comfort after linear design, and studies the safety, continuity, consistency and economy of design. The traditional economic evaluation, financial evaluation and engineering technology are basically used to compare the advantages and disadvantages of the route schemes in China. The main problem is that the influence of environment and society is ignored, which can not fully reflect the scientificity and rationality of the route, and the economically optimal scheme is not necessarily the optimal scheme.

Linear design is the most economical method, which can not only reduce the materials needed for engineering construction, but also reduce the driver's vision, reduce the blind area of sight and reduce the occurrence of traffic accidents to a certain extent, but it is not only the linear design of highway alignment. The research shows that setting a straight line for a long time will lead to the fatigue of drivers and passengers because of the single line shape and monotonous landscape along the line, and the long straight line cannot be designed indefinitely in highway line shape design.

3 The straight line is too long. In plain areas, long straight lines are often designed in route design in order to save costs and shorten the construction period, because the route selection is rarely or basically not limited by topography.

4 The length of the transition curve does not meet the requirements of summation, and the route designers of some highways only meet the minimum length of the transition curve, without considering the alignment of the route comprehensively, so that the length of the transition curve does not meet the requirements of alignment and superelevation.

5 ultra-high cross slope and ultra-high transition section are not suitable. When expressway passes through residential areas, vehicles must speed limit and be subject to local traffic control. In this case, it is beneficial to reduce the superelevation cross slope appropriately. However, in the design, only the cross slope design is often considered, and the same two-way cross slope can not be designed, which makes it difficult for vehicles to turn around and turn, thus causing traffic accidents.

4 highway route analysis method

Highway route optimization has two characteristics: incommensurability of design objectives and contradiction between design objectives. The incommensurability of design goals means that there is no uniform measure for each goal, so it is difficult to compare. The contradiction between linear design objectives means that if a certain scheme is adopted to improve or change a certain target value, the optimal value of another target may become better or worse.

5 Reliability research and analysis

The application of reliability theory in highway alignment design has a long history, but the application of reliability theory in highway alignment design in China has not been fully carried out. Reliability theory is widely used in some fields, especially in structural engineering and geotechnical engineering, and also in traffic engineering, such as highway drainage pipeline design, traffic signal time interval reliability analysis, signal timing design and so on. Reliability theory is a limit state design based on probability theory, which describes the reliability of engineering structures with probability.

The Code for Highway Route Design clearly stipulates that highway route design should comprehensively design the plane, longitudinal section and cross section of the highway, so as to achieve smooth plane, balanced longitudinal section and reasonable cross section; Highway route design specification is the basis of highway design, and it is also the standard to evaluate the reliability and quality of highway route design, which is manifested in a series of normative clauses, both of which are principled. There is also a system status information, including the results of route design and the constraints of highway environment, which are aimed at every detail. The data of highway design results are the main technical and economic indicators, and environmental constraints include topography, geology, hydrology and so on. Compare the present situation of highway design with the evaluation standard, compare the environmental constraints of highway with the present situation of design, analyze the rationality of route design, and demonstrate that it needs improvement, is basically reasonable but still has room for improvement, basically meets the technical requirements but does not meet the economic requirements, and meets the economic requirements but the actual technical indicators are not ideal; Classify the problems found in highway analysis and evaluation, find out the key points, put forward scientific and reasonable optimization methods, put them into practice, and re-analyze and optimize the results of highway optimization.

6 conclusion

There are still some problems in the current highway route design. Starting from the problems existing in highway route design, some solutions are put forward. Only in this way can we save labor and time, effectively save resources and reduce construction costs. Therefore, the design work should be considered from multiple angles, and the route scheme should be designed reasonably to provide safety guarantee for traffic vehicles. It is hoped that the method proposed in this paper can play a safer and more economical role in highway route design.