Simultaneous optimization of horizontal and vertical alignments for highways

Chew, Ek Peng; Goh, C. J.; Fwa, T F

doi:10.1016/0191-2615(89)90008-8

Cited by 79 publications

(49 citation statements)

References 7 publications

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“…Based on the analytical techniques used, the methods can be classified into three categories: optimization methods, speed-profile methods, and special methods (Table 1). The optimization methods address construction cost for horizontal alignments (Trietsch 1987;Easa 1988; Lee and Cheng 2001) or both horizontal and vertical (combined) alignments (Chew et al 1989). The operatingspeed (OS) profile methods maximize alignment design consistency based on trial and error and can accommodate horizontal or combined alignments (Krammes et al 1995;Ottesen and Krammes 2000;Fitzpatrick and Collins 2000;Easa 2003).…”

Section: Introductionmentioning

confidence: 99%

Establishing highway horizontal alignment to maximize design consistency

Easa¹,

Mehmood²

2007

Can. J. Civ. Eng.

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Highway design consistency is one of the important criteria in selecting the geometric features of proposed or existing alignments of two-lane rural highways. Operating-speed (OS) profile models have been used to evaluate design consistency by trial and error. For a proposed new highway, however, there may be geometric and physical constraints, and selection of these elements by trial and error to achieve optimal design consistency would be difficult, if not impossible. This paper presents an optimization model that establishes highway horizontal alignment to achieve maximum design consistency based on the OS profile. The decision variables of the model include radius of horizontal curves, spiral curve lengths, length of speed-change (SC) segments, and acceleration and deceleration rates. The objective function of the model minimizes the mean OS difference or the maximum OS difference for successive geometric features along the highway section. Application examples and sensitivity analysis are presented to illustrate the capabilities of the model in evaluating improvement strategies and to ensure that the model produces sound optimum alignments. The proposed model, which complements existing optimization models that mainly address highway construction cost, should be of interest to highway practitioners and engineers.Résumé : La constance dans la conception des autoroutes est l'un des critères importants pour la sélection des caractéristiques géométriques d'alignements proposés ou existants de routes rurales à deux voies. Jusqu'à présent, des modèles de profil de la vitesse sur les routes sont utilisés pour évaluer la constante de conception par essais et erreurs. Pour une nouvelle route proposée, il peut y avoir des contraintes géométriques et physiques et la sélection de ces éléments par essais et erreur pour atteindre la constante de conception optimale pourrait donc être difficile, voire impossible. Cet article présente un modèle d'optimisation qui établit un alignement horizontal de l'autoroute afin d'obtenir la constante maximale de conception en se basant sur le profil de vitesse sur les routes. Les variables décisionnelles du modèle comprennent le rayon des courbes horizontales, les longueurs des courbes en spirales, la longueur des segments de changement de vitesse ainsi que les taux d'accélération et de ralentissement. La fonction objective du modèle minimise la différence moyenne ou maximale de la vitesse sur les routes pour des caractéristiques géométriques successives le long de la section de route. Des exemples et une analyse de sensibilité sont présentés pour illustrer les capacités du modèle à évaluer les stratégies d'amélioration et assurer que le modèle produit des alignements optimaux valides. Le modèle proposé, complémentant les modèles d'optimisation existants qui abordent principalement les coûts de construction des routes, devrait intéresser les praticiens et les ingénieurs en voirie.

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Section: Introductionmentioning

confidence: 99%

Establishing highway horizontal alignment to maximize design consistency

Easa¹,

Mehmood²

2007

Can. J. Civ. Eng.

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“…In this context, dynamic programming, state parameterisation, and genetic algorithm approaches were applied to find optimal route candidates in the threedimensional manner. 1,2,19,[27][28][29] In addition to the complex and comprehensive modelling abilities of these three-dimensional models, they are not practically applicable for most alignment problems and may not guarantee exact solutions every time. 1,5 In the light of these, a hypothetical WGE concept, focusing on the vertical alignment, has recently been suggested to determine the optimum grades, practically for both hand and computer calculations.…”

Section: Literature Reviewmentioning

confidence: 99%

“…In this context, several researchers 10-14 have developed horizontal alignment models; although more emphasis has been given to vertical alignment models so far. [15][16][17][18][19][20][21][22][23][24][25] The major discrepancies among the developed twodimensional models are based on the variety of optimisation techniques, namely linear programming, quadratic programming, gradient search, state parameterisation and dynamic programming.…”

Section: Literature Reviewmentioning

confidence: 99%

Method for optimal vertical alignment of highways

Göktepe

Lav

Altun

2009

Proceedings of the Institution of Civil Engineers - Transport

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This paper presents a methodology to consider vague soil parameters required for earthwork optimisation, and to develop a genetic algorithm-based constrained curve-fitting technique required for highway vertical alignment process. The weighted ground line method is an earthwork optimisation methodology based on a hypothetical reference line and taking into account three soil properties to calculate realistic cut–fill volumes, namely swelling potential, compactibility percentage, and material appropriateness percentage. In this study, fuzzy rule-based inference methodology, which utilises previous experiences that can be expressed with linguistic terms, is employed to characterise swelling/shrinkage behaviour. In addition, material appropriateness concept is also adopted into developed optimisation methodology by a parametric algorithm using technical specifications and geotechnical data. Consequently, the genetic algorithm approach is employed for the determination of final grade line considering weighted ground elevations. The method involving an algorithm to consider the soil parameters as well as an evolutionary computation-based constrained curve-fitting technique produces outstanding geometric alignments.

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“…The early work focused especially on modeling techniques, such as calculus of variations [1,2], numerical search [3,4], linear programming [5,6], network optimization [7][8][9], and dynamic programming [3,8,10,11]. Recent studies advanced the methodology by removing unrealistic assumptions and incorporating real-world constraints.…”

Section: Introductionmentioning

confidence: 99%

Concurrent Optimization of Rail Transit Alignments and Station Locations

Lai¹,

Schonfeld

2016

Urban Rail Transit

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Designing urban rail transit systems is a complex problem, which involves the determination of station locations, track geometry, and various other system characteristics. Most of the previous rail transit route optimization studies have focused on the alignment design between predetermined stations, whereas a practical design process has to account for the complex interactions among railway alignments and station locations. This paper proposes a methodology for concurrently optimizing station locations and the rail transit alignment connecting those stations, by accommodating multiple system objectives, satisfying various design constraints, and integrating the analysis models with a geographical information system database. The methodology incorporates demand and station costs in the evaluation framework and employs a genetic algorithm for optimizing the decision variables for station locations, station types, and track alignments. It is expected that transit planners may greatly benefit from the proposed methodology, with which they can conveniently and efficiently optimize candidate alternatives. The Baltimore Red Line is used as a case study to demonstrate how the model can find very good solutions in regions with complex geography.

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Simultaneous optimization of horizontal and vertical alignments for highways

Cited by 79 publications

References 7 publications

Establishing highway horizontal alignment to maximize design consistency

Establishing highway horizontal alignment to maximize design consistency

Method for optimal vertical alignment of highways

Concurrent Optimization of Rail Transit Alignments and Station Locations

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