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A roadway path is most commonly perceived as a 3-D element structure placed within its surrounding environment either within or outside urban areas. Design guidelines are usually strictly followed to ensure safe and comfort transportation of people and goods, but in full alignment with the terrain configuration and the available space, especially in urban and suburban areas. In the meantime, vehicles travelling along a roadway consume fuel and emit pollutants in a way that depends on both the driving attitude as well as the peculiar characteristics of road design and/or pavement surface condition. This study focuses on the environmental behavior of roadways in terms of fuel consumption, especially of heavy vehicles that mainly serve the purpose of freight transportation within urban areas. The impact of horizontal and vertical profiles of a roadway structure is theoretically considered through the parameters of speed and longitudinal slope, respectively. Based on theoretical calculations with an already developed model, it was found that the slope plays the most critical role, controlling the rate of fuel consumption increase, as an increase ratio of 2.5 was observed for a slope increase from 2% to 7%. The variation was less intense for a speed ranging from 25 to 45 km/h. The investigation additionally revealed useful discussion points for the need to consider the environmental impact of roadways during the operation phase for a more sustainable management of freight transportation procedures, thereby stimulating an ad hoc development of fuel consumption models based on actual measurements so that local conditions can be properly accounted for and used by road engineers and/or urban planners.

The introduction of connected automated vehicles (CAVs) on freeways raises significant challenges, particularly in interactions with human-driven vehicles, impacting traffic flow and safety. This study employs traffic microsimulation and surrogate safety assessment measures software to delve into CAV–human driver interactions, estimating potential conflicts. While previous research acknowledges that human drivers adjust their behavior when sharing the road with CAVs, the underlying reasons and the extent of associated risks are not fully understood yet. The study focuses on how CAV presence can diminish conflicts, employing surrogate safety measures and real-world mixed traffic data, and assesses the safety and performance of freeway interchange configurations in Italy and the US across diverse urban contexts. This research proposes tools for optimizing urban layouts to minimize conflicts in mixed traffic environments. Results reveal that adding auxiliary lanes enhances safety, particularly for CAVs and rear-end collisions. Along interchange ramps, an exclusive CAV stream performs similarly to human-driven ones in terms of longitudinal conflicts, but mixed traffic flows, consisting of both CAVs and human-driven vehicles, may result in more conflicts. Notably, when CAVs follow human-driven vehicles in near-identical conditions, more conflicts arise, emphasizing the complexity of CAV integration and the need for careful safety measures and roadway design considerations.

The low-speed turning maneuverability of vehicles is closely related to a well-known offtracking phenomenon which occurs when the rear wheels of a turning vehicle deviate towards the inside of a horizontal curve. Although numerous mathematical models and computer programs for vehicle swept path analysis have been developed in the past, only a few of them can calculate the maximum transient offtracking of a turning vehicle, yet with limited accuracy. The authors were motivated by this fact to find a new mathematical solution for maximum transient offtracking calculation of a single-unit vehicle when negotiating circular curves. In the first stage, a transcendental equation defining vehicle maximum transient offtracking position is derived and numerically solved by Python 3.10.12. In the second stage, the polynomial regression model predicting accurate numerical solutions of the transcendental equation with the desired level of accuracy was developed and tested. The new calculation method is simple enough to simply take the vehicle datum length, circular curve radii, and turn angle, while instantly producing the maximum transient offtracking value, without the need to draw any of the vehicle movement trajectories.

Road vertical alignment design is a multi-objective design problem that needs to consider multiple constraints. Intelligent design based on optimization algorithms cannot wholly solve problems, such as multi-objective, uncertainty, and constraint dynamics. The article proposes a model of dynamically transforming design constraints into feasible regions as the design develops, to provide decision information before design actions rather than performing constraint evaluation after the design that reduces the empirical estimation. The design actions are divided into new design actions and modifying design actions, and corresponding feasible regions derived from constraints of design specifications and control elevations are established, respectively. Geometrical equations and program algorithms of feasible regions are described in the graphic environment, which is applied to the vertical alignment design to improve the design efficiency and decision-making level.

Organic soil is characterised by high compressibility and should be improved so that it can be used for construction. The use of every method of soil improvement requires knowledge of the compressibility parameters. One of these parameters is the constrained modulus. The constrained modulus can be determined using laboratory or in-situ tests. In this study, the constrained modulus of organic soil was determined using oedometer and piezocone tests (CPTU). The author analysed subsoil under an approximately 250 m section of a designed road in north-eastern Poland. The constrained modulus of organic soil sampled from four different depths was determined in oedometer tests. Piezocone tests were conducted at 18 points located every 15 m along the length of the section concerned. To determine the constrained modulus based on the cone resistance from CPTU tests, the knowledge of the α and αM coefficients is needed. For the tested soil, the optimal range of the α coefficient from 0.4 to 0.7 was determined. The αM coefficient ranged from 0.4 to 0.8. The value of the constrained modulus of organic soil obtained from the oedometer tests, depending on the effective stress, ranged from approximately 100 kPa to 400 kPa. The constrained modulus of the tested soil decreased with depth, which both research methods proved.

Walking is the most important mode of transport in the “Global South. ” Depending on the location, the mode accounts for between 33 and 90% of trips. Despite its importance and the notion that walking is available to all, there are vast parts of the population that cannot use the mode, as infrastructure is not conducive. The gender and ability neutral approach to infrastructure provision ignores the needs of up to 75% of inhabitants, leading to isolation and the inability to access services. This paper describes the results of a desktop study that uses various types of literature and secondary data sources to conduct a qualitative assessment of the inclusivity of non-motorized transport and vulnerable population groups (women, children, the elderly, and people with disabilities) in its planning and implementation approach, rather than actual implementations. Cape Town is used as a case study city. Results were verified by local experts. Gender neutral planning and roll out of infrastructure has been slow and there is no evidence at all that women, children, and the elderly are considered in the “Global South” context. Regarding people with disabilities, there has been some progress. Tactile paving and drop curbs are occasionally included. However, due to a lack of training of contractors and personnel that audits implementation projects, the quality of infrastructure for people with disabilities is poor. In the case of Cape Town, the qualitative scores are a mere two credits out of a maximum of 75 credits regarding the non-motorized transport, gender and social inclusion in transportation planning and practice. The authors suspect that scores in many African cities will be even lower. As with many other cities in the “Global South,” and more specifically in Africa, Cape Town needs to change its management structure, break down the silos between departments, embrace the input of representatives of vulnerable groups during infrastructure design and implementation and, more importantly, increase the budget for non-motorized transport. There is also a clear need for improved training for contractors and city infrastructure auditors, as implemented infrastructure is often substandard. The study resulted in the development of a hierarchical framework.

This study provides a comprehensive approach to the management of uncontrolled accesses, namely, access points without traffic lights, stop signs, right-of-way, yield signs, or right-turn acceleration/deceleration lanes. These elements of the road network are often associated with several safety issues given the inadequate conditions and limitations regarding their location, design, and visibility. This paper provides new insights into the geometric and functional design of uncontrolled accesses and contributes to the area of safety management measures. The implementation of the approach to a selected case study allows for the description of the methodology and to find interesting results concerning the cause-effect relationship between geometry-related variables and accidental events. In particular, the study focuses attention on the key factors of the geometric and functional design of accesses: radius and width, with the aim of defining more adequate design criteria aimed at improving safety. Furthermore, several interesting considerations are drawn relating to the types of connection transition shapes, allowing the selection of the most dangerous type for the safety of drivers and pedestrians. The most important finding is the high risk correlated to an access point with no materialised elements guiding the entry manoeuvre.

With the development of intelligent transportation, dedicated highway lanes for autonomous vehicles (AVs), necessary for ensuring their right of way, have emerged as critical issues in intelligent transportation research, which makes it necessary to set up specialized lane-changing buffer zones in the lane adjacent to the dedicated one. Restricted by the current situation of intelligent transportation systems, based on NGSIM data, this study filters out typical lane-changing description data featuring lane-changing behaviors and constructs a principal component analysis (PCA) model containing factors affecting the longitudinal driving distance during the whole lane-changing procedure. The validity of the model is evaluated with a significance test. Comparing the PCA model to a general linear regression model, suggestions on setting the length of lane-changing buffer zones are put forward. The length of the buffer zone mainly considers speed, acceleration, and the flow in the dedicated lane. In general, a shorter buffer zone length can be achieved by increasing the design speed of the buffer zone, raising the headway of AVs in the dedicated lane, reducing the acceleration rate of lane-changing vehicles, and reducing the time proportion of the lane change preparation stage, which occurs earlier in the procedure.

The stability of slopes and embankments under the influence of static and seismic loads has been the subject of study for many researchers. This paper stands for an attempt to present tolerable move-ments, based on caused damage on slopes of the embankments, as well as to connect them with natural disas-ters of the environment.

Improving road safety is not only reliant on engineering aspects but also on the surrounding landscape, which plays an indispensable role in drivers’ visual perception. As a part of road landscapes, green areas affect road safety by screening or framing views. While vistas could be highlighted in safe spots in order for road users to enjoy their travel, in dangerous scenic points, visual attractions need to be concealed to lessen visual distractions and the risk of accidents. This study aims at optimizing road safety through sustainable landscape design in one of the dangerous Tehran–Dizin road bends to meet both road safety and environmental requirements. In doing so, cone of vision formulas have been applied to calculate measures of green landscape features so as to hide visual distractions and upgrade safety. To design such a green landscape, green resources and their characteristics have been elaborated, and native species have been suggested in plant composition, which can improve the sense of place, enhance the environment, and create a sustainable landscape. The research shows that a cone of vision could functionally be employed to increase the success of a designed green landscape, especially in situations where two-dimensional approaches are not sufficient.

This study investigated the nature and causes of unsafe driving behavior at roundabouts through an on-road study. Four urban double-lane roundabouts with different layouts were selected for an on-road study. Sixty-six drivers (41 males and 25 females) aged 18–65 years took part in the study. Unsafe behaviors observed during the in situ survey were divided into three different categories: entry unsafe behaviors, circulation unsafe behaviors, and exit unsafe behaviors. Three chi-square automatic interaction detection (CHAID) analyses were developed in order to analyze the influence of roundabout characteristics and maneuvers on unsafe behaviors at double-lane roundabouts. The results confirmed the awareness that double-lane roundabouts are unsafe and inadvisable. More than half of unsafe driving behaviors were found to be entry unsafe behaviors. Moreover, the entry radius was found to be the geometric variable most influencing unsafe driving behaviors.

The article focuses on the importance of the strength and durability of highways due to the projected increase in freight traffic. It also describes the consequences of uneven distribution of loads in traffic lanes, depending on the prevailing traffic in each lane. The studies, that were carried out earlier by various scientists, were taken into account, thankfully to which results were obtained on the composition of the traffic flow, the difference in the loading of road pavements, as well as the stress-strain state of road structures. As a result, a model that reflects the dependence of the influence of the speed of movement of vehicles on the dynamic deformation of structures, was developed. Consequently, a number of design solutions were established to ensure the required strength of all structures.

Lidar and other remotely sensed data such as UAV photogrammetric data capture are being collected and utilized for roadway design on an increasing basis. These methods are desirable over conventional survey due to their efficiency and cost-effectiveness over large areas. A high degree of relative accuracy is achievable through the establishment of survey control. In this case study, elevations (z-values) derived from mobile-terrestrial lidar, aerial lidar, and UAV photogrammetric capture collected with survey control were statistically compared to conventionally surveyed elevations. A cost comparison of the methods is also included. Each set of z-values corresponds to a discrete horizontal point originally part of the conventional survey, collected as cross-sections. These cross-sections were surveyed at three approximate tenth-mile sample locations along US-30 near Georgetown, Idaho. The cross-sections were collected as elevational accuracy verification, and each sample location was selected as an area where the mobile-terrestrial lidar in particular was expected to have more difficulty achieving accuracy off the road surface. Processing and analysis were performed in Esri ArcMap 10.6, and all data were obtained from the Idaho Transportation Department, District 5. Overall, the aerial lidar elevations were found to be closest to conventionally surveyed elevations; on road surface and level terrain, mobile-terrestrial and UAV photogrammetric capture elevations were closer to the conventionally measured elevations.

According to national (Greek) and European legislation on road infrastructure safety management, road safety auditing is mandatory for the Trans-European Road Network. This paper presents the development of a training course and educational material for candidate road safety auditors in Greece, aiming to adequately prepare them to conduct road safety audits. In particular, the principles upon which the road safety audit training course is based, the learning objectives, the course outline and the proposed framework of the curriculum are presented. The training course takes into consideration recent developments in road safety, as well as local conditions and needs. Because it places emphasis on the implementation of the Safe System and human factors in road design, it may contribute to the development of a positive safety culture among highway professionals involved in the road design and road operation process. The process of its development may be regarded as a proposal for good practice for the development of professional development training programmes, addressing the relevant training needs and achieving the relevant training objectives.

New Serbian policies on road design introduce the concept of operating speeds. Decades ago, national policies were based on the constant design speed concept. Among other design parameters, in relation to that constant design speed, minimum radii of horizontal and vertical road geometry were determined. Introduction of the operating speed concept provides for more realistic prediction of speed levels along the road. Unlike the constant design speed, operating speed levels vary along the road, reaching higher levels in curves with larger radii, on straight sections and on reverse curves and dropping down to the design speed level in horizontal curves with the minimum radius. Consequently, besides a constant Stopping Sight Distance (SSD), which is calculated from the constant design speed, the new term, Required Sight Distance (RSD) is introduced. RSD varies along the road, as it is calculated from the operating speed, which also varies along the road. Appropriate RSD analyses are crucial on road rehabilitation projects, since a simple resurfacing that enables higher speed levels, without providing increased RSD, may hamper the safety of a newly resurfaced road. Software tools for predicting operating speed levels and optical analyses of the road are also presented in this paper. Software tools for RSD analyses enable the import of lines of sight into the 3D model of the roadway and their export into the cross sections extracted from the model, thus facilitating the obstacle removal. Also demonstrated are tools for determining Available Sight Distance (ASD), which are based on triangulated 3D models of the roadway as well.

The driver, through sight, acquires a lot of information from the road environment, most of which is necessary for his safe route. However, if the amount of information per unit of time is excessive, potentially dangerous situations of overload could be created. Even the opposite condition, that of a road that does not adequately stimulate the cognitive functions of the driver, may pose certain safety problems because it triggers the so-called boredom effect. This phenomenon, generally classified under the name of workload, was treated with great depth in literature but, probably, sufficiently detailed methodology has not yet been proposed for making forecasts on this variable along the road. The difficulty of preparing a reliable model can be explained by some of the characteristics of the road environment: many uncertain variables, including the human factor, choosing the most appropriate analytical method, lack of appropriate databases. The purpose of this article, therefore, is to present a prediction model based on the analysis of physiological workload by means of head-eyes movements and fuzzy techniques applied to a real context. The results obtained, although limited by the observed data set, allowed for the prediction with some accuracy of the tendency of the workload, referring also to the overload and under load thresholds position of which was defined on the basis of performance measurements along the road under consideration. In the first stage of the study the methodology is applied to the design of maintenance on an existing road, but once the correctness of the procedure is established, it can also be extended to new roads.

A utilização individual e recorrente do automóvel particular nas sociedades contemporâneas tem promovido uma elevada fragmentação das comunidades locais bem como impactos directos na saúde pública das populações. Perante a inevitabilidade destes fenómenos tem havido forte aposta das autoridades europeias na segurança rodoviária. Neste aspecto, poderá ser considerado paradigmático o caso da baixa da cidade de Lisboa, um local de confluência dos principais movimentos pendulares de acesso à cidade de Lisboa. Perante estes resultados será de propor que a elevada sinistralidade pedonal no período em análise possa de alguma forma estar correlacionada com a elevada concentração de estabelecimentos de diversão nocturna. O presente estudo promove uma análise epidemiológica dos atropelamentos ocorridos na baixa da cidade de Lisboa, num período de quatro anos (2006-2009), de forma a aferir a influência de determinados aspectos estruturais característicos daquela área emblemática da cidade de Lisboa.

Traffic safety can be defined as the quality of driving task outcome, which in its turn depends on factors within the system “Driver–Vehicle–Road”. Therefore, if analyzing concept of traffic safety from viewpoint of driving task, it must include relationships following from interactions among all the system elements. To understand these relationships and fix essential factors and elements, which must be taken into account, when making design solution or analyzing it, the system model was established. Based on this model the system functioning was analyzed. Results obtained explain importance of content and quality of information in sources from which driver obtains it for decision making. It was also established, that visual road image is the main information source for decision making in situation, where the traffic flow influence is small. Therefore, content and quality of this information, contained in road image, visible for driver, is formed and must be checked during design process.

Driving behaviour is a direct consequence of the stimuli received from the road infrastructure, from the surrounding environment and from the atmosphere inside the vehicle. Almost all of these perceptions, which affect steering, are received through the drivers’ eyes. For this reason, in this paper visual behaviour was examined in order to deduce new indexes connected to mental workload. To this aim, a consistent sample of drivers covered a rural road inside a vehicle, while their eye movements and driving activities were being recorded with suitable instruments. The quantification of some variables involved in the trials permitted the evaluation of visual behaviour and determination of a measure of mental workload, identifying also any situations where performance was compromised. Some reports between mental workload and road geometry, summarized in a few tables, could represent a further aid for road designers and managers.

Multi-objective analysis is a popular tool to solve many economic, managerial and construction problems. The objective of this research is to develop and implement a methodology for multi-objective optimization of multi-alternative decisions in road construction. After a rough overview of the articles dealing with the multi-objective decision and assessment of road design alternatives described by discrete values, Multi-Objective Optimization on the basis of the Ratio Analysis (MOORA) method was selected. This method focuses on a matrix of alternative responses on the objectives. A case study demonstrates the concept of multi-objective optimization of road design alternatives and the best road design alternative is determined.

Multi-attribute analysis is a popular tool in many economical, managerial, constructional etc problems. The objective of this research is to develop and implement a methodology for multi-attribute assessment of multi-alternative decisions in road construction. After a rough overview of multi-attribute decision support for assessment of road design alternatives, the COPRAS approach was selected. This methodology is applicable to the problems with large numbers of scenarios and criteria. A case study is used to demonstrate the concept of multi-attribute assessment of road design alternatives and the best road design alternative is determined. The research has concluded that the COPRAS method is appropriate for use.

In the Netherlands, as in most other countries in the world, car mobility is increasing rapidly. The accident rates are decreasing, but the decrease is not large enough to compensate for the extra road traffic victims brought about by the increased mobility. Without strong, innovating efforts the number of road traffic victims will increase and the Dutch road safety targets (minus 50% fatalities and minus 40% serious injuries in 2010 compared to 1986) will be out of reach. Therefore, in the early nineties the concept of “sustainable safety” was introduced with the aim to give road safety a new impulse. In a sustainably-safe traffic environment, road infrastructure is, first and for all, designed in such a way that the chance of an accident occurring is very limited. Secondly, if an accident cannot be prevented, the chance of serious injury will be markedly reduced. A very important characteristic of a sustainably-safe traffic system is that all relevant characteristics of infrastructure, vehicle and traffic regulations are maximally tuned to the capabilities and limitations of the road users as well as their acceptance of the measures. The article discusses the sustainable safety principles and measures and the organisational and financial framework. It also provides an estimate of the expected benefits in terms of road traffic fatalities. It is estimated that a successful implementation of sustainable safety measures could indeed result in the targeted 50% reduction in road traffic fatalities, even when the number of vehicle kilometres double. The use of quantitative road safety targets is considered to have created a positive, open climate for these types of new and innovating policies.

The term ‘Context Sensitive Solutions’ was adopted by the Federal Highway Administration in 1997 and is a synonym of flexibility that allows the designer to balance the safety, mobility and preservation of environmental resources. When the optimal use of design criteria produces an unacceptable solution, the correct application of design value outside the current guidelines with a particular attention to safety and legal risk is needed. In this case, a feasible alternative meets the purpose of design and is considered constructible and maintainable within social, economic and environmental constraints. Unlike in many other countries, road standards in Italy do not permit to work out a simple solution to the problem of flexibility. Specifically, one of the most debated subjects, concerning the items of the Italian Ministerial Decree (MD) 5/11/2001 confer with a designer the possibility of deviating from prescriptive obligations on condition to suggest some appropriate safety analysis. However, it does not indicate any methodology to objectively quantify removal effect from the reference values established by the rule. At this purpose, the paper suggests an analytical instrument for controlling design values outside the current guidelines applying a methodology based on interval analysis, a technique generally used for managing uncertain variables. The procedure applied to designing a planimetric curve has identified the most significant variables and produced some range in which they may be retained acceptable, though outside the limits of the geometric standard. Santrauka 1997 m. JAV Federalinė greitkelių administracija (Federal Highway Administration) patvirtino terminą,,kontekstiniai sprendimai“ (context sensitive solutions), kuris yra žodžio ,,lankstumas“ (flexibility) sinonimas, leidžiantis projektuotojui subalansuoti aplinkos išteklių saugą mobilumą ir išsaugojimą. Kai optimalus projektuojamasis kriterijus yra nepriimtinas, reikalingas tinkamas projekto vertės taikymas, atsižvelgiant į jau esamas rekomendacijas, ypač pabrėžiant saugą ir teisinį rizikos objektą Šiuo atveju galima alternatyva atitinka projektavimo tikslą ir yra laikoma naudinga bei tinkama aptarnavimui, atsižvelgiant į socialinius, ekonominius ir aplinkos apsaugos ribojimus. Kaip ir daugelyje kitų šalių, kelių standartai Italijoje neleidžia lanksčiai spręsti problemos, pateikiant paprasčiausią sprendimą Aišku, kad vienas iš labiausiai svarstomų klausimų, pateiktų Italijos Vyriausybės dekrete (MD 5/11/2001) suteikia projektuotojui galimybę nukrypti nuo norminančių ribojimų su sąlyga, kad bus pasiūlyta tinkamos saugos analizė ir sprendimas. Tačiau tai nėra metodika, galinti objektyviai išmatuoti ir įvertinti skaičiais nukrypimo poveikį nuo nustatytų atskaitinių verčių. Straipsnyje siūloma analitinė priemonė, galinti kontroliuoti projekto vertes už jau esamų gairių ribų, taikant intervalinę analizę, naudojamą tvarkant neapibrėžtus kintamuosius. Analitinė priemonė, taikyta projektuojant planimetrinę kreivę, atskleidė svarbiausius kintamuosius ir nurodė ribas, kai galima jais remtis, esant jiems už geometrinio standarto ribų. Резюме В 1997 г. Федеральное управление шоссейных дорог Министерства транспорта США подтвердило термин «контекстные решения» (context sensitive solutions), который является синонимом слова «гибкость» (flexibility). Это в свою очередь позволяет проектировщику при выполнении проекта сбалансировать между собой безопасность окружающих ресурсов, мобильность и сохраняемость. Когда оптимальный проектировочный критерий неприемлем, возникает необходимость в требуемом решении с учетом при этом уже имеющихся рекомендаций, обеспечении безопасности и правового риска проектируемого объекта. В данном случае возможная альтернатива должна удовлетворять цель проекта и быть полезной и нужной в использовании с учетом различных требований и ограничений, например, таких, как социальные, экономические и природоохранные. Дорожные стандарты Италии, как и многих других стран, не позволяют гибко решить проблему с помощью простейшего решения. Представленные в Декрете (MD 5/11/2001) правительства Италии положения дают возможность проектировщику отклониться от нормируемых ограничений при условии, что будет предложен анализ и принято решение, удовлетворяющие требуемый уровень безопасности. Однако при этом методика не позволяет объективно численно определить и оценить воздействие отклонения от установленных рекомендуемых значений величин. В статье представлено аналитическое средство, позволяющее контролировать отклонения в проекте от установленных рекомендуемых значений величин с использованием интервального анализа для конкретно неопределенных величин. Аналитическое средство применялось при проектировании планиметрической кривой. Определены важнейшие переменные и указаны границы величин, которые можно использовать за границами геометрического стандарта. Reikšminiai žodžiai: lankstumas, intervalinė analizė, projektavimo standartai, kelių standartai, sauga Ключевые слова: гибкость, интервальный анализ, стандарты проектирования, дорожные стандарты, безопасность

Multi‐objective analysis is a popular tool to solve many economic, managerial and construction problems. The objective of this research is to develop and implement a methodology for multi‐objective optimization of multi‐alternative decisions in road construction. After a rough overview of the articles dealing with the multi‐objective decision and assessment of road design alternatives described by discrete values, Multi‐Objective Optimization on the basis of the Ratio Analysis (MOORA) method was selected. This method focuses on a matrix of alternative responses on the objectives. A case study demonstrates the concept of multi‐objective optimization of road design alternatives and the best road design alternative is determined. First published online: 27 Oct 2010

This paper presents a new approach to the design methodology of road routes, in literature often referred to as the polynomial alignment. The author proposes the use of the so-called general transition curves that have been described in detail in his earlier research papers. General transition curves employ only one curvature extremum, and the whole curved transition between two extreme points of zero curvature value is described by a single equation. As a result, the curves are very useful for the creation of route geometry in accordance with the principles of polynomial alignment. The paper describes the main concept of polynomial alignment and presents equations of curves which can be used in the proposed alignment procedure. In addition, the paper gives a detailed description of design procedures.