Evaluation of Pavement Runoff and Driving Safety on Highway Curve Segment

Runoff depth distribution on the concave and circular curve sections is obtained from a two-dimensional numerical simulating model in order to analyze the temporal and spatial variation of the pavement runoff on the curve section. The two-dimensional model verified by the field data can depict the alignment of pavement more accurately as compared to the empirical equation and a one-dimensional model. The runoff on the concave section and circular curve section is compared for the free water drainage and centerline drainage. Results show that a two-dimensional model is essential for the analysis of the centerline drainage. The runoff depth can be controlled by a reasonable curb height and location interval. The drainage type affects the variation of the runoff depth on the nearside lane, and the maximum water depth can be up to more than 80 mm on the concave section and nearly 60 mm on the circular curve section under centerline drainage. Besides the existing hydroplaning results, the runoff depth difference of the wheel trace should be considered to evaluate driving safety. Sideslip will occur when the depth difference becomes more than 6 mm under condition that the runoff depth is less than the tread depth (7 mm). When the runoff depth is more than the tread depth, sideslip will occur once the depth difference exceeds 4 mm.

Evaluating the Impact of Sight Distance and Geometric Alignment on Driver Performance in Freeway Exits Diverging Area Based on Simulated Driving Data

The decision sight distance (DSD) at freeway exits is a major factor affecting traffic safety. Based on the Hechizhai Interchange in Xi’an City (Shaanxi Province, China), this paper designs a simulation experiment. Through a simulator study and a questionnaire survey, this paper discusses the impact of the DSD, 1.25 times the stopping sight distance (SSD) and a circular curve deflection on a driver’s driving state (including steering wheel angle rate and steering wheel angle frequency domain). Thirty volunteers participated in this research. The result shows that (1) it is safer to drive on an exit that meets DSD. (2) If it only meets the 1.25 times the SSD requirement, the overloaded driving tasks and operation would be more likely to cause crashes. The driving state of the driver on the right circular curve is obviously better than that on the left circular curve, because changing lanes to the right on the left circular curve does not meet the driver’s expectations. (3) Left and right circular curve should be treated differently in the driving area and the constant sight distance requirements should not be applied. (4) The left circular curve should be more stringent to ensure driving safety.

A Novel Analysis of the Smooth Curve with Constant Width Based on a Time Delay System

In this paper, we analyze the C∞ smooth curve of constant width using the characteristic equation of a time delay system. We prove that a closed convex curve must be a circle if it is still a smooth curve of constant width after taking any number of derivatives. Finally, the simulation results are presented for analyzing the influence of derivative orders on a smooth non-circular curve of constant width.

Сalculation methodology and determination of efforts in vault

Problem. In this article we offer the meth-odology of calculation, based on the idea of dismem-berment of vault on the separate archs of single width. It is recommended for the estimation of efforts in the designed and damaged vaults. Also offered a methods of calculation effort in serried vaults. As spatial inflexibility of cross vault below than inflexi-bility of serried vault, then it is necessary to execute the calculation of the cheek arch abstracted from the tray of cross vault also. If the outline of tray is exe-cuted on a circular curve, then it is possible to take methodology of calculation of archs with the outline of axis a curve as catenoid. Goal. The proposed methodology for calculating closed and cross vaults is also based on the idea of dividing the arch into separate arches of unit width. The results of studies of efforts and rational forms of arches of V.A. Kiselev [1]. Methodology. Calculation based on the idea of dismemberment of vault on the separate archs of single width. Recommended for the estimation of efforts in the designed and damaged vaults. A method over of calculation of dome is brought for determina-tion of effort in serried vaults. Results. At the choice of outline of axis of arch it is necessary aspires to that an axis, on possibility, coincided with the curve of pressure. Such outline of axis is rational, as there are only central forces of N in an arch. Flexion mo-ments M and transversal forces of Q are equal to the zero. The coincidence of axis of arch with the curve of pressure can be got for the three-hinged arch. For the statically undetermined arch of complete coinci-dence of axis with the curve of pressure attaining is impossible, so that the origin of flexion moments at any her outline is inevitable. Originality. The tech-nique based on the separation of flat elements from the spatial structure does not show the reserves of strength of the structure. Experience of long-term operation of vaulted structures designed or verified by calculation using similar methods [2], [9] shows caution and reliability. Practical value. The tech-nique is also suitable for assessing the strength of damaged vaults with collapsed corners or walms.

Application of modern geodetic tools in the operation of railway reconstructions

This research considers the survey of the circular curve of the operating railway using an electronic total station, which determines the coordinates of points on the curve and calculates the coordinates of the main points of the circular curve. The goal is obtaining information with sufficient accuracy about the spatial position of the parameters of the railway plan, i.e. the device of the railway plan: turning angles, radiuses, lengths of straight lines and curves. Recommendations for determining the elements necessary to locate the main points of curves and their coordinates are considered. The advantage of this method is the simplicity of calculation, which allows the compiled program and high efficiency of determining the main points of curves using a modern geodetic device-the electronic total station Trimble VX (USA).

Speed of Trains Running on Parallel Track Connections Using Curved Turnouts

The issue of connecting parallel main tracks located in a circular curve by means of curved turnouts is discussed in the pa-per, focusing on determining the achievable train speed. Selected geometries are used in the analysis. The curved turnout diverging track radii and the corresponding train speeds are determined. An analytical notation is used, thereby creating greater options in specific applications. It is shown that the speed of trains running on parallel track connections depends on the type of basic turnout subjected to curving (i.e. mainly on the radius of this turnout), while the second very important factor is the value of the track cant used. In each case, the determined speed resulting from the diverging track radius is lower than the speed on the main tracks. While discussing the general principles of constructing parallel track connections in a circular arc using curved turnouts, it is pointed out that in some situations the speed of travel must be further reduced due to the need to connect the ends of the diverging tracks with a circular arc. Keywords: railway turnouts, turnout curving, speed analysis, connecting diverging tracks

Influencing Factors on Vehicles Lateral Stability on Tunnel Section in Mountainous Expressway under Strong Wind: A Case of Xi-Han Highway

When a car is running at high speed, the canyon wind at the bridge-tunnel junction in the mountainous area brings along the acceleration effect. The aerodynamic lateral force will cause the vehicle sideslip and unsteady steering, which is extremely harmful to driving safety. In this paper, Xi-Han Expressway is taken as the research object to analyze the influencing factors of vehicle’s lateral stability by combining the theoretical research of the finite element method, automobile aerodynamics, and speed limit with field investigation and simulation test. CarSim software is used for simulation to explore the influence of different positions of the circular curve on vehicle lateral stability. The results show that the wind level affects the tunnel exit’s unfavorable section on the circular curve. The larger the wind level, the larger the proportion of the tunnel exit’s unfavorable section on the circular curve. The proportions of tunnel exit’s unfavorable section on the circular curve under 6–9 wind levels are 33.33%, 38.89%, 55.56%, and 66.67%, respectively. In addition, the lateral stability of vehicles under level 6–8 wind scale is the worst when the tunnel exit is located at 5° position on the circular curve. The results indicate the influence of strong wind on the lateral stability of vehicles in mountainous expressway. The research can optimize the design of the highway tunnel group and provide the basic theory and method basis for the quantitative management and scientific management of the road traffic management department.

Magnetic-Measuring Square in the Measurement of the Circular Curve of Rail Transport Tracks

In rail transport, measuring the actual condition of a circular curve of a railway track is a key element of track position monitoring not only during operation but also during final works. Predicting changes in its position in the horizontal plane is one of the most important related scientific issues. This paper presents the results of measurements performed with an innovative measuring device called the Magnetic-Measuring Square (MMS). The aim of the research was to demonstrate the acceptability of using the MMS. Horizontal versines of a rail track curve were measured as three neighboring points on a curve (using the method of lacing/stringlining, also called the three-point or the Hallade method), and the perpendicularity of rail joints and shortenings were measured. The MMS device presented in this article was used to measure versines and differences in rails lengths (rail shortenings in the curve) in the operating mode involving a laser distance meter with a laser beam (laser power P < 1 mW, laser wavelength λ = 635 nm) with a target cross, a camera, and a surveying measuring disk. The measurement results confirmed that it is possible to employ the MMS to monitor the geometry of railway track fragments such as track transition curves and railway track curves in rail transport.