1,661 research outputs found
Designing an ecologically optimized road corridor surrounding restricted urban areas: a mathematical methodology
The use of optimization techniques for the optimal design of roads and railways has increased in recent years. The environmental impact of a layout is usually given in terms of the land use where it runs (avoiding some ecologically protected areas), without taking into account air pollution (in these or other sensitive areas) due to vehicular traffic on the road. This work addresses this issue and proposes an automatic method for obtaining a specific corridor (optimal in terms of air pollution), where the economically optimized road must be designed in a later stage. Combining a 1D traffic simulation model with a 2D air pollution model, and using classical techniques for optimal control of partial differential equations, the problem is formulated and solved in the framework of Mixed Integer Nonlinear Programming. The usefulness of this approach is shown in a real case study posed in a region that suffers from serious episodes of environmental pollution, the Guadalajara Metropolitan Area (MĂ©xico)Xunta de Galicia | Ref. ED431C 2018/50Sistema Nacional de Investigadores | Ref. SNI-52768Programa para el Desarrollo Profesional Docente | Ref. PRODEP/103.5/16/806
HIGHWAY ALIGNMENT ALONG THE CORRIDORS USING REMOTE SENSING AND GEOGRAPHICAL INFORMATION SYSTEM - PERUNDURAI TO PALANI, TAMILNADU, INDIA
Best route location and highway alignment selection process is a complicated one due to many variables it must be considered. Geographic Information Systems (GIS) can easily represent such variables, including topography, environment, built-up areas and geology variables. It is to identify the short route for the vehicles travelling from Perundurai to Palani and to diminish the time journey for the vehicles with possible routes for laying eco-friendly highway. This study took compensation of GIS capabilities that present the ability to overlay maps, merge them and execute spatial analysis on different layers of information in either two or three dimensions. GIS model for route location and highway alignment developed and worn to create alternate highway route applications. After the alternatives are preliminarily deliberated using ArcGIS9.3, the imitation is used to analyze, evaluate and to select the best alternative with least impacts on environment and economy. The selected highway is supposed to connect three districts viz. Erode, Tirupur and Dindugal. In final stages of examination and assessment, the replica envelops the high capabilities in analyzing the impacts of every alternatives, with buffering and spatial relations.ĂÂ ĂÂ Three different routes are identified as left, middle and right routes. Right route is identified as best route which fulfils least cost with eco-friendly environment, material reduction on number of bridges and culverts
Multiobjective railway alignment optimization using ballastless track and reduced cross-section in tunnel
The increasing need for railway planning and design to connect growing cities in inland mountainous areas has pushed engineering efforts toward the research of railway tracks that must comply with more restrictive constraints. In this study, a multiobjective alignment optimization (HAO), commonly used for highway projects, was carried out to identify a better solution for constructing a high-speed railway track considering technical and economic feasibilities. Then, two different and innovative scenarios were investigated: an unconventional ballastless superstructure, which is more environment-friendly than a gravel superstructure, and a reduced cross-section in a tunnel, which enables a slower design speed and then, less restrictive geometric constraints and earthmoving. The results showed that the first solution obtained a better performance with a slight increase in cost. Moreover, both scenarios improved the preliminary alignment optimization, reducing the overall cost by 11% for the first scenario and 20% for the second one
The Evolution of Computer-Aided Road Design Systems
In order to locate a path between two known locations on a ground surface, a large number of alternative paths should be evaluated considering physical, economical, and environmental factors. Optimization techniques can be used to search for a path that minimizes the total costs while satisfying the design and environmental constraints. These techniques can result in considerable time savings in forest road design. Initially, these optimization techniques have been applied to highway design and recently, they have been applied to forest road design. This paper describes the evolution of the optimal route location systems used in both highway and forest road design based on ten criteria. The paper concludes by describing some of the unsolved problems in forest road design
GEOMETRIC AND ENVIRONMENTAL CONSIDERATIONS IN HIGHWAY ALIGNMENT OPTIMIZATION
The highway alignment optimization problem is modeled to identify the preferred alignment alternatives which minimize total cost and satisfy the highway design standards. Several mathematical models have been developed during the past decades, among which the Highway Alignment Optimization (HAO) model has been used in several practical highway design projects with satisfactory results. However, several major cost components, such as vehicle operating cost and environmental cost are estimated roughly, and should be improved to yield more precise cost estimates and to allow optimization of lane widths. These are the HAO model features which this thesis seeks to improve.
Lane width is an important factor in highway design, which is related to the travel speed, safety, as well as earthwork cost. This thesis employs Newton's method and Finite Difference method to search for the appropriate lane width. The preferred lane width found in the case study is 10.6 feet, for which the total cost is $233 million, and 12.5% less than the total cost at 12 feet lane width. In addition, this thesis improves the vehicle operating cost prediction by calculating the vehicle resistance force and horsepower, and estimating the fuel consumption based on the fuel consumption rate (g/hp-hr). Moreover, the environmental cost, particularly the vehicle emissions cost is incorporated in the newly improved HAO model. It is found that the vehicle emission cost decreases by 9% after including the environmental cost component in the model objective function.
The results of the case study and sensitivity analyses indicate that the improved HAO model can find good highway alignments efficiently in tough topographic environmental. Moreover, the model can jointly consider the social, economic and environmental consequences, and result in less fuel consumption and pollutant emissions
Overview of Performance Based Practical Design
State transportation agencies (STAs) have increasingly turned to practical design and performance based practical design (PBPD) to inform project development and implementation â and to reduce project costs while optimizing systemwide benefits. PBPD is a design-up philosophy that encourages agencies to formulate projects to meet the purpose and need rather than adhering to ostensibly immutable design standards. This paper reviews practical design and PBPD concepts and initiatives and their application in a variety of contexts. It also summarizes best practices STAs can use to develop a PBPD program. As a holistic approach to project design, PBPD underscores context sensitive solutions that balance the needs of all roadway users, including motorists, bicyclists, and pedestrians. Common PBPD solutions include opting for low-cost enhancements, such as striping, signing, and rumble strips, as opposed to realignment; narrowing shoulder widths; redesigning projects to lower right-of-way costs; modifying interchange designs; and using design exceptions to build projects that fulfill project objectives. STAs committed to establishing robust PBPD programs will typically require 18 to 24 months to get a program off the ground. For an initiative to succeed, it is critical for executive leadership in an agency to advocate for PBPD; that agency staff learn about practical design and ongoing PBPD programs in other states; that a baseline performance evaluation of the tools, concepts, and resources currently used for project development be conducted; and that changes made to the project development process are thoroughly documented. The report closes with a series of recommended performance metrics the Kentucky Transportation Cabinet should consider adopting to improve its monitoring of critical bridge and roadway assets
OPTIMIZATION OF STATION LOCATIONS AND TRACK ALIGNMENTS FOR RAIL TRANSIT LINES
Designing urban rail transit systems is a complex problem, which involves the determination of station locations, track geometry, right-of-way type, and various other system characteristics. The existing studies overlook the complex interactions between railway alignments and station locations in a practical design process. This study proposes a comprehensive methodology that helps transit planners to concurrently optimize station locations and track alignments for an urban rail transit line. The modeling framework resolves the essential trade-off between an economically efficient system with low initial and operation cost and an effective system that provides convenient service for the public. The proposed method accounts for various geometric requirements and real-world design constraints for track alignment and stations plans. This method integrates a genetic algorithm (GA) for optimization with comprehensive evaluation of various important measures of effectiveness based on processing Geographical Information System (GIS) data.
The base model designs the track alignment through a sequence of preset stations. Detailed assumptions and formulations are presented for geometric requirements, design constraints, and evaluation criteria. Three extensions of the base model are proposed. The first extension explicitly incorporates vehicle dynamics in the design of track alignments, with the objective of better balancing the initial construction cost with the operation and user costs recurring throughout the system's life cycle. In the second extension, an integrated optimization model of rail transit station locations and track alignment is formulated for situations in which the locations of major stations are not preset. The concurrent optimization model searches through additional decision variables for station locations and station types, estimate rail transit demand, and incorporates demand and station cost in the evaluation framework. The third extension considers the existing road network when selecting sections of the alignment. Special algorithms are developed to allow the optimized alignment to take advantage of links in an existing network for construction cost reduction, and to account for disturbances of roadway traffic at highway/rail crossings. Numerical results show that these extensions have significantly enhanced the applicability of the proposed optimization methodology in concurrently selecting rail transit station locations and generating track alignment
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