Straight Road Sections Research Articles

DETERMINATION OF TRAFFIC FLOW PARAMETERS IN DIFFERENT TRAFFIC FLOW INTERACTION CASES

Modelling of straight road section consisting of one traffic line gives the opportunity to simulate “follow the car” system. In general it looks like a line of vehicles, going one after another. Kinetic theory, used in this paper describes traffic flow system as a straight unbroken line with limited flow speed and concentration. Such model also gives the opportunity to derive traffic lines intersections. For example, intersection could be derived like a point with traffic lines coming and outgoing from this point by only changing boundary conditions. Mathematical model is built using characteristic method.

Road extraction based on fuzzy logic and mathematical morphology from pan‐sharpened ikonos images

AbstractAutomatic extraction of geospatial features has been the subject of extensive research in the past three decades. Here, an approach based on fuzzy logic and mathematical morphology is proposed, to extract main road centrelines from pan‐sharpened IKONOS images. In the IKONOS images, a standard deviation of 10 grey levels has been measured for the road classes. In the proposed fuzzy logic system, just one arbitrary pixel (up to a maximum of 3 pixels) provides an adequate initial value. Road identification requires neither the numbers of the classes nor the corresponding mean values; then, using advanced morphological concepts, the road centreline is extracted. The method is applied to pan‐sharpened IKONOS images of urban, suburban and rural areas around the Pyramids in Egypt, and Rasht City and Kish Island in Iran. The extracted road centrelines have an average error of 0·504 pixel and root mean square error of 0·036 pixel. The method is more accurate at road intersections and on curves than on straight sections of road. The extracted road is then used as a direct input to a geographical information system (GIS).

Perceptual lane width, wide perceptual road centre markings and driving speeds

The possibility that driving speeds could be reduced through the use of lane delineation was explored. Using a high-fidelity driving simulator, 28 experienced drivers were measured on seven two-lane rural roads with lane widths of 3.6, 3.0, or 2.5 m, and with either a standard centreline (control), a wide painted hatched road centre marking, or a wide white gravel road centre marking. Driving speeds were reduced on the narrowest lane width road, and further reduced on straight road sections that contained the centre marking with painted hatching. It was concluded that the narrow lane width increased steering workload and reduced speeds through a speed-steering workload trade-off, whilst the hatched road centre marking enhanced peripheral visual speed perception, leading to higher speed estimations and slower speeds. Therefore, narrowing the lane width below 3.0 m by using a painted hatched road centre marking should be an effective way to reduce driving speeds.

Braking Stability of Articulated Vehicles on Highway

SUMMARYThis paper is concerned with the running stability of tractor-semitrailer combination at braking. Firstly, we construct nonlinear equations of motion for the articulated vehicles, which have 9 degrees of freedom. Secondly, simulation study is carried out to show the vehicle performance in realistic situation. Jack-knifing on the straight road section was recreated by the simulation in consideration of road gradient not only for longitudinal direction but also for lateral direction. By using the concept of load rate of each tire, we confirmed that the model shows the mechanism of the jack-knifing on straight road section, and the motion of limit performance conditions. Finally, the relationship between limit performance, road gradient condition, and vehicle parameters is shown. These results emphasize the importance of observation of the tire load rate. Especially, rear axle of tractor should be considered when we discuss the limit performance of jack-knifing.

1408 制動時における連結車両の安定性解析(OS0 交通・物流機械のダイナミクス,振動,騒音,制御)

This paper is concerned with the running stability of tractor-semitrailer combination at braking. Firstly, we construct nonlinear equations of motion for the articulated vehicles, which have 9 degrees of freedom. Secondly, simulation study is carried out to show the vehicle performance in realistic situation. Jack-knifing on the straight road section was recreated by the simulation in consideration of road gradient not only longitudinal direction but also lateral direction. By using the concept of load rate of each tire, we confirmed that the model shows the mechanism of the jack-knifing on straight road section, and the motion of limit performance conditions. Finally, the relationship between limit performance, road gradient condition, and vehicle parameters is shown. These results emphasize the importance of observation of the tire load rate. Especially, rear axle of tractor should be considered when we discuss the limit performance of jack-knifing.

Experimental study of propagation characteristics on roads on a snowy mountain

Experimental results of radio propagation characteristics on roads on snowy or snow-capped mountains are discussed. Propagation tests were carried out on the horizontal and vertical polarization characteristics in a frequency range from VHF to X-band (150 MHz to 4.7 GHz). Field strengths along the road and field distributions in the cross section were measured. The attenuation constants in a straight-road section were obtained by the least-squares method using measured data. It is shown that the attenuation constants are experimentally minimum in a frequency range of 1-3 GHz for each polarization, and that field strengths in the cross section are close to cosine distribution in the horizontal direction, and in the vertical direction increase nearly monotonically with increasing elevation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The lighting of curves on arterial roads

The influence of installation geometry on light technical parameters has been investigated using computer design procedures. The main conclusions are: (1) in order to maintain the standard of lighting the luminaire spacing on curves must be decreased from that used on the straight section of road; (2) the closing up of spacing must be greater if the luminaires are placed on the inside of the curve rather than on the outside of the curve; and (3) a simple rule can be used to determine the curve spacing, based on the spacing used in the straight section and the radius of curvature of the curve. Implications to road safety and costs are discussed.