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Showing 5 results for Road Network
Volume 5, Issue 1 (3-2017)
Abstract
Finding a minimum allowable radius length of a circle horizontal curve is essential to reduce earthwork cost or damage to the forest ecosystem, as well as make driving more comfortable. The present study is conducted i) to analyze different radius lengths of circle horizontal curves using an integrated approach consists of a Civil3D in concert with the field surveys, and ii) to propose a set of geometric design criteria which are more consistent with the existing condition of forest road network in Hyrcanian forest, north of Iran. Depth of the rutting (i.e., machine footprint) and soil mechanical properties are examined for a total of 36 existing horizontal curves with different radius lengths. Further, technical characteristics (i.e., stopping sight distance, horizontal sight line offset and turning speed) and a few parameters on pavement damage are included and incorporated into the research objective. No-statistical differences between radius lengths of the horizontal curve for classes of 10-15 and 16-20 m may associate with dissimilarity in the soil mechanical properties and in the dimension of the rut depth. These findings confirmed that it is therefore possible to shorten allowable radius length of a circle horizontal curve to at least 12 m under a longitudinal slope of 5% for forest road network in the north of Iran.
Volume 12, Issue 2 (6-2012)
Abstract
Minimum Spanning Tree (MST) is a mathematical programming problem that may be applied for analyzing transportation network structure and its performance, like its connectivity and link prioritization. Generally, the cost associated with each link is its Free Flow Travel Time (FFTT), however in this paper this concept is developed to the case of a loaded network with capacity constraints and its application to transportation network planning is examined for times of disaster, when the life of many people is involved. In this paper equilibrium travel time for a loaded network is proposed as the link cost and the problem is formulated and solved for Tehran province network. Results show that based on equilibrium travel times, the total cost of MST will have an 8 percent increase from 25973 to 28081 seconds and about 30 percent of the links in the new MST will change. It is also observed that if the MST based on FFTT is used for computing the total cost of the loaded network, the total cost will be 30232 seconds which demonstrates 17 percent increase in cost and 9 percent in error.
Volume 15, Issue 1 (3-2025)
Abstract
Aims: The purpose of this article is to study the caravanserais in this area and present architectural plan patterns for suburban caravanserais on the historical road network from Isfahan to Rey and Saveh based on the spatial composition of the room with the stable.
Methods: The data collection method of this research is based on field observations and impressions, library studies, examination of architectural documents and maps of caravanserais, and study of aerial images. The analysis method is based on interpretive, historical, and comparative approaches. The method of obtaining information is inductive reasoning. 60 caravanserais have been identified in this area. From the above statistical population, 13 caravanserais have been selected as study samples. The selection of these samples was purposeful and non-probability.
Findings: The research findings indicate that some caravanserais are very similar and were built in the same period of time and their typologies are also similar to each other, which is due to the existence of a single organization and a common architect and designer, and as a result, their architectural plans and details are similar. In the statistical population of this study, 13 types and architectural patterns of caravanserais were identified based on the study of their architectural plans.
Conclusion: There are some similarities and differences among caravanserais in the research samples. Caravansers that are on a common historical path with common cultural, social and historical characteristics often have similar architectural features, so this characteristic can be used to intervene in them.
Volume 15, Issue 4 (7-2013)
Abstract
In the last few years, public awareness has been on the increase about short- and long-term effects of forest roads construction on the environment. Therefore, forest road managers have to be concerned about the negative impacts and mitigate them as much as possible. This research conducted multi-criteria analysis techniques in a useful way to define the effective criteria and propose a model for forest road network planning and assessment so that both economic and environmental costs are minimized. The model was used for evaluating the alternatives and a sensitivity analysis was then performed to verify the model. Results of sensitivity analysis showed that, there were two alternatives out of nine, with the lowest negative impacts. As a result, analytic hierarchy process and sensitivity analysis (AHP-SA) revealed that the criteria slope, soil texture and landslide susceptibility had the highest weight values, respectively, and the criteria soil texture and distance from stream networks and distance from faults were especially sensitive to the changes. In addition, the sensitivity analysis proved that the model proposed in our analysis was almost reliable and stable, and only the first and second priorities were replaced in priority levels when the weight values of criteria were changed. Results showed that the methodology was useful for identifying road networks that met environmental and cost considerations. Based on this work, the authors suggest future work in forest road planning using multi-criteria evaluation and decision making be considered in other regions and that the road planning criteria identified by the experts in this study can be useful.
Mrs Zahra Pourahmad, Dr Babak Saffari, Dr Shekoofeh Farahmand,
Volume 24, Issue 3 (9-2024)
Volume 24, Issue 3 (9-2024)
Abstract
Introduction
In recent years, the ever-increasing population growth and rampant use of personal transportation and daily trips have caused many problems in the field of transportation, including high fuel consumption, air pollution, noise, high density streets, reduced physical activity, etc. In many metroplolitan areas during the past decades, the sudden increase of motor vehicles has caused heavy street traffic in intra-city trips, and the main reason for this can be considered the weak relationship between urban morphology and transportation, in other words, urban forms that avoid pedestrians and encourage motor trips. Urban morphology is one of the most important and main factors that affect the demand for urban transportation. The quality of land use (density of residential units or their dispersion) forms the important basis of urban morphology. In the formation of urban morphology, natural and human factors play varried roles, among them road network is of paramount importance in construction and morphology of a city. Since urban morphology has a significant effect on urban transportation, how to establish a strong relationship between urban morphology and travel modes has has always been of great interst of researchers. This study is aiming at investigating the impact of morphology characteristics on urban transportation demand. In this research, features of urban morphology, such as overall residential density, connectivity index, and the average width of roads, with the help of demographic characteristics, such as population density, female and female working poulation, total working population etc., on demand for urban transportation have been ivestigated. These include four parameters such as creation of public and personal trips and attraction of public and personal trips on in 186 traffic areas of Isfahan city.
Methodology
This research has been conducted with a descriptive causal approach based on the data and information required in the study areas. To achieve the research goals, 186 traffic areas of Isfahan City have been studied. For analyzing the characteristics of urban morphology, including average width of roads, overall residential density, and connectivity index (street density), in the form of GIS maps have been investigated, and for demographic characteristics, the population and housing census map of Isfahan City was obtained and researched from the Deputy Planning and Human Capital Development Organization of Isfahan Municipality. Then, using the map of 186 traffic areas of Isfahan City, the amount of these variables was calculated and extracted by GIS software. Moreover, the information related to urban transportation demand based on public transportation demand, including public travel creation, public travel attraction, and personal transportation demand, including personal travel creation and personal travel attraction from the origin-destination matrix of the year 2021 of Isfahan city on a normal working day and at the peak hour of 7:00 to 8:00 a.m., the transportation and traffic department of Isfahan municipality has been obtained and used for evaluation. In the present research, in order to reach a complete and comprehensive answer, after extracting the data from GIS software, the Eviuse software was used. According to the number and nature of the research variables, the specification of the model is done using the multivariate regression method and the weighted least squares method. GIS software was also used for drawing the maps.
Findings
The research findings show that in the TSS and JSS models, with the increase in the average width of traffic areas, the creation and attraction of personal travel have also increased, and in the TSO and JSO models, the creation and attraction of public travel have decreased with the increase in the average width of traffic areas. In TSS model, the coefficient is negative and in JSO model, the coefficient is positive, which shows that with an increase in the overall residential density, the use of private transportation decreases and the use of public transportation increases. In terms of street density, which also indicates the connection index, the coefficient value is positive in TSS and negative in TSO model. The results also show that women in general use public transportation, but working women use private transportation more. The estimation of TSS model shows that as population is aging in the traffic areas of Isfahan City, the preferrence in using personal transportation has been rising. In JSS model, the parking variable has a direct relationship with the attraction of personal travel. In the personal travel attraction model, health-therapeutic use and commercial use have a direct relationship with the attraction of personal trips, and in the public travel attraction model, commercial, educational, and health-therapeutic uses have a direct relationship with the attraction of public trips. Finally, the increased number and variety of the users will also increase intra-city trips.
Discussion and Conclusion
In this research, an attempt has been made to investigate the effect of urban morphology variables on urban transportation demand with a general perspective. The results of the estimation of the research models show that the widening of urban roads as a management policy for intra-city travel demand increases people's trips using personal transportation and as a result, increases the number of road users. Street density, which indicates the number of higher streets and therefore greater connectivity, has a direct relationship with citizens' use of private transportation. Residents of areas that have higher overall residential density and population density, which indicates denser urban fabric and more dispersion, are less likely to use personal transportation, and people in those areas prefer to use public transportation and walking options. Also, as the age of the residents of the area increases, they use private cars for their daily trips. Another examination of the results of the research indicates that areas with parking facility, will attract passengers who have used private transportation compared to the areas that do not have such possibility. In general, as the total working population increases in the areas, they use personal transportation to go to their workplace, and it can be said that the female population uses public transportation more for their daily trips. In the public travel attraction model, the positive coefficient of commercial use is higher than the coefficient of health-therapeutic use and educational use, and with the increase in the number of commercial uses, the attraction of public travel increases to a greater extent. In the personal travel absorption model, the effect value of the healthcare usage coefficient is higher than the commercial usage coefficient and it shows that with the increase in the number of healthcare usages, the absorption of personal travel will increase. Moreover, the increased number and variety of the users will also increase intra-city trips.
In recent years, the ever-increasing population growth and rampant use of personal transportation and daily trips have caused many problems in the field of transportation, including high fuel consumption, air pollution, noise, high density streets, reduced physical activity, etc. In many metroplolitan areas during the past decades, the sudden increase of motor vehicles has caused heavy street traffic in intra-city trips, and the main reason for this can be considered the weak relationship between urban morphology and transportation, in other words, urban forms that avoid pedestrians and encourage motor trips. Urban morphology is one of the most important and main factors that affect the demand for urban transportation. The quality of land use (density of residential units or their dispersion) forms the important basis of urban morphology. In the formation of urban morphology, natural and human factors play varried roles, among them road network is of paramount importance in construction and morphology of a city. Since urban morphology has a significant effect on urban transportation, how to establish a strong relationship between urban morphology and travel modes has has always been of great interst of researchers. This study is aiming at investigating the impact of morphology characteristics on urban transportation demand. In this research, features of urban morphology, such as overall residential density, connectivity index, and the average width of roads, with the help of demographic characteristics, such as population density, female and female working poulation, total working population etc., on demand for urban transportation have been ivestigated. These include four parameters such as creation of public and personal trips and attraction of public and personal trips on in 186 traffic areas of Isfahan city.
Methodology
This research has been conducted with a descriptive causal approach based on the data and information required in the study areas. To achieve the research goals, 186 traffic areas of Isfahan City have been studied. For analyzing the characteristics of urban morphology, including average width of roads, overall residential density, and connectivity index (street density), in the form of GIS maps have been investigated, and for demographic characteristics, the population and housing census map of Isfahan City was obtained and researched from the Deputy Planning and Human Capital Development Organization of Isfahan Municipality. Then, using the map of 186 traffic areas of Isfahan City, the amount of these variables was calculated and extracted by GIS software. Moreover, the information related to urban transportation demand based on public transportation demand, including public travel creation, public travel attraction, and personal transportation demand, including personal travel creation and personal travel attraction from the origin-destination matrix of the year 2021 of Isfahan city on a normal working day and at the peak hour of 7:00 to 8:00 a.m., the transportation and traffic department of Isfahan municipality has been obtained and used for evaluation. In the present research, in order to reach a complete and comprehensive answer, after extracting the data from GIS software, the Eviuse software was used. According to the number and nature of the research variables, the specification of the model is done using the multivariate regression method and the weighted least squares method. GIS software was also used for drawing the maps.
Findings
The research findings show that in the TSS and JSS models, with the increase in the average width of traffic areas, the creation and attraction of personal travel have also increased, and in the TSO and JSO models, the creation and attraction of public travel have decreased with the increase in the average width of traffic areas. In TSS model, the coefficient is negative and in JSO model, the coefficient is positive, which shows that with an increase in the overall residential density, the use of private transportation decreases and the use of public transportation increases. In terms of street density, which also indicates the connection index, the coefficient value is positive in TSS and negative in TSO model. The results also show that women in general use public transportation, but working women use private transportation more. The estimation of TSS model shows that as population is aging in the traffic areas of Isfahan City, the preferrence in using personal transportation has been rising. In JSS model, the parking variable has a direct relationship with the attraction of personal travel. In the personal travel attraction model, health-therapeutic use and commercial use have a direct relationship with the attraction of personal trips, and in the public travel attraction model, commercial, educational, and health-therapeutic uses have a direct relationship with the attraction of public trips. Finally, the increased number and variety of the users will also increase intra-city trips.
Discussion and Conclusion
In this research, an attempt has been made to investigate the effect of urban morphology variables on urban transportation demand with a general perspective. The results of the estimation of the research models show that the widening of urban roads as a management policy for intra-city travel demand increases people's trips using personal transportation and as a result, increases the number of road users. Street density, which indicates the number of higher streets and therefore greater connectivity, has a direct relationship with citizens' use of private transportation. Residents of areas that have higher overall residential density and population density, which indicates denser urban fabric and more dispersion, are less likely to use personal transportation, and people in those areas prefer to use public transportation and walking options. Also, as the age of the residents of the area increases, they use private cars for their daily trips. Another examination of the results of the research indicates that areas with parking facility, will attract passengers who have used private transportation compared to the areas that do not have such possibility. In general, as the total working population increases in the areas, they use personal transportation to go to their workplace, and it can be said that the female population uses public transportation more for their daily trips. In the public travel attraction model, the positive coefficient of commercial use is higher than the coefficient of health-therapeutic use and educational use, and with the increase in the number of commercial uses, the attraction of public travel increases to a greater extent. In the personal travel absorption model, the effect value of the healthcare usage coefficient is higher than the commercial usage coefficient and it shows that with the increase in the number of healthcare usages, the absorption of personal travel will increase. Moreover, the increased number and variety of the users will also increase intra-city trips.
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