Technical-Economical Evaluation of Chain Vertical Alignment in Underground Urban Subways: The Case of Qom Subway, Line A

Abdi Kordani, Ali,Mehrara Molan, Amirarsalan The Korean Society for Railway 2014 International Journal of Railway Vol.7 No.2

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

The Effect of Shoulder on Safety of Highways in Horizontal Curves: With Focus on Roll Angle

Ali Abdi Kordani,Sajad Javadi,Afshin Fallah 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

Analysis of crash rates in the world reveals a number of factors including road geometry and human behavior which should bescrutinized. In fact, many studies have been conducted on how to decrease crash rates that are related to the relationship betweenhuman behavior and road geometry. In this research, 324 scenarios were evaluated to simulate vehicle dynamics with the use ofCarsim and Trucksim simulation software. To be more specific, the impacts of shoulder width, slope of shoulder and material ofshoulder surface on the enhancement of safety based on driver behavior and road geometry were studied, through the use of vehicledynamic simulation. In the study, based on the position of vehicles in horizontal curves in various types of shoulders, models wereachieved for the roll angle of vehicles. The research included: 1- 3D modeling by using simulation software, 2- Evaluating roll anglechanges in different types of vehicle locations on shoulders versus speed changes, and 3- Presenting multiple linear regressionmodels to connect the variables by statistical programs. Results indicate that shoulder type (width, material and cross slope)influences the safety considering the roll angle of the vehicle. This influence depends on dynamic and geometric characteristics andtype of the vehicle.

The Effect of Combined Horizontal Curve and Longitudinal Grade on Side Friction Factors

Ali Abdi Kordani,Amirarsalan Mehrara Molan 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.1

The relationship between side friction factor and longitudinal grade is investigated for horizontal curves considered in threedimensions, and new models for estimating side friction factors for different vehicle types are presented. The study consists of threeparts: (1) a series of simulation tests using the CarSim and TruckSim multi-body simulation software packages; (2) multiplexregression analysis; and (3) presentation of recommended formulas for the side friction factor. Two different driving behaviors areconsidered in the simulation process: in one, the driver negotiates the curve at constant speed; in the other, the driver brakes whilepassing downgrades. Side friction factors are also studied separately for each axle of a vehicle. Greater side friction factors are foundon downgrades for all vehicle types when cornering. From the viewpoint of skidding, the most critical situation is found for the rearaxle of a sedan. In addition, braking is found to have a significant effect on side friction factors. The results and models from thisstudy can be used in the geometric design phase by highway engineers to design safer roads.

Technical-Economical Evaluation of Chain Vertical Alignment in Underground Urban Subways

Ali Abdi Kordani,Amirarsalan Mehrara Molan 한국철도학회 2014 International Journal of Railway Vol.7 No.2

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

Proposing an Elliptic Equation for the Symmetrical Sag Vertical CurvesBased on Sight Distance in Highway

Bahram Shirini,Ali Abdi Kordani 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.12

The sight distance at night is one of the most important driving safety factors. Sag vertical curves are one of the important elements of roads, which require a sufficient sight distance at night. The headlight sight distance is used for determining the length of the sag vertical curves. Presently, the parabolic curve is mainly used in symmetrical sag vertical curves. The present study aimed to propose the elliptic curve as a new alternative for the parabolic curve. An elliptic equation is developed for use in vertical curve and sight distance of the sag elliptic vertical curve in nighttime is calculated based on the characteristics of the road geometry. Results indicate that contrary to the parabolic curve, the sight distance of the elliptic curve varies depending on the vehicle location and increases as the vehicle moves forward on the curve; therefore, driver sees the end of curve in elliptic curves much earlier than parabolic curves. The results also indicate that the sight distance of the parabolic curve is more than that of the elliptic curve in the shortest length after the curve beginning (up to 8% of the curve length) while the sight distance of the elliptic curve is more than that of the parabolic curve at the rest of the curve (at least 92% of the curve length). Based on the obtained results, for S > L, the stopping sight distances of the elliptic and parabolic vertical curves are equal.

Vehicle Safety Analysis based on a Hybrid Approach Integrating DEMATEL, ANP and ER

S. R. Seyedalizadeh Ganji,Amir Abbas Rassafi,Ali Abdi Kordani 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11

Vehicle related safety is the principal focus of many agencies and organizations targeting road safety issues. There are many conflicting factors contributing to safety in motor vehicle operations. Unfortunately, the lack of reliable crash data makes it extremely difficult to evaluate the crash causations associated with defective vehicles. Furthermore, clarifying the interrelationships among vehicle related factors causing accidents is very complicated when the conventional decision techniques are used. This study aims to employ a hybrid decision method based on DEMATEL (decision-making trial and evaluation laboratory) and ANP (Analytic Network Process) to construct an Influence Relations Map (IRM) as well as obtain the influential weight of vehicle-related criteria. An empirical case study is provided to demonstrate the implementation process. This paper also employs an Evidential Reasoning algorithm (so-called ER) for assessing the inter-city buses in terms of vehicle safety in order to deal with the uncertainties associated with incomplete input data. The ER improves decision making process by using a belief decision matrix and the Demspster-Shafer theory of evidence. The results and findings reveal that the braking system is the most important criterion impacting vehicle safety, followed by fuel supply and electrical systems.