Abstract The purpose of highway geometric design is to provide safe and economical highways. One of the utmost important geometric design element for safely travel that should be satisfied is visibility on designed road. This can achieved by providing adequate sight distance in both horizontal and vertical alignments. Minimum sight distance that should be provided at all points along highway is stopping sight distance SSD. In the design of vertical curves AASHTO's Geometric design Policy uses the sight distance requirement as a major criterion in curve length determination. Moreover, sight distance has great effect on highway constructional cost because more required sight distance means more vertical curve length, which in turn means more earthwork materials. Consequently, safety and economics can be considered as a major criterion in design of highways. The AASHTO's model involved design speed, perception-reaction time, and frication factor as a parameters used for SSD computations on level sections. On inclined surfaces, an additional parameter denoted by (G), which reflect grade of sloped surface on SSD. In the present paper a new approximate methodology and Equations are formulated though which a suitable design grade value can be estimated on vertical curves where the grade not constant then utilizing this value to compute SSD on these curves and hence compute vertical curve length corrected for grade effect. Generalization of present methodology is carried out by derivation a general mathematical solution. From these derivations it has been found that the suitable grade value for Type I and Type III (initial and final grade are descending and ascending) is half of the largest grade among G1 and G2. While the design grade value is the average value of G1 and G2 for Type II and Type IV (both grade are descending or ascending). Comparison with other grade estimation on vertical curves suggestions showed that the present methodology produces more reasonable and economical value because the obtained length is no longer to be uneconomical as compared with other suggestions. At the same time it provides a safe value used in all design cases those reflects the actual case as compared with other suggestions those ignored or reduced the effect of grade.
Traffic engineers frequently are engaged in evaluating the performance of different facilities of the highway system. The facility in this project includes freeway section. In design of a freeway, a forecast demand volume is used with known design standards for geometric features and a desired level of service to compute the number of lanes required for the freeway section in question. The design application is straight forward for each usage, but trial-and- error operation analysis may be required to evaluate alternative design. Design requires a detailed traffic forecast, including volumes, peaking characteristics, traffic composition, and specifics of vertical and horizontal alignment for the section under study. The aim of this paper is the design analysis of a freeway with a heavy recreational vehicles. This analysis involves the consideration of three examples of freeways. Given known geometric roadway conditions and projected traffic conditions , the design analysis yields an estimation of the number of lanes and of the speed and density of the traffic stream. This paper has described the procedure for determining the number of lanes of freeway basic sections as presented in the Highway Capacity Manual (HCM, 2000) and HCS2000 software.
The geometric design of highway alignment consists mainly of the design of horizontal alignment and Vertical alignment. The more important step in horizontal alignment design is the curve radius determination. The equation used for horizontal curve radius determination is developed with assumption that when vehicle run on curved section, there are an acting force on it. This force include the centrifugal force that try to push vehicle out off its path , on the other hand there are resisting forces try to keep the vehicle on its path. Those include the friction between road surface and tires and forces resulting from sloping the highway cross section. When a vehicle on rural highway with high embankment the wind Pressure will play an important role in force system acting on vehicle because of increasing in wind pressure intensity at these conditions (rural highway, i.e open areas, high embankment). The purpose of this paper is to present a new equation for horizontal curve radius determination taking in to account the wind force effect in addition to other forces acting on vehicle The resulting equation relates vehicle length, height and weight and the wind pressure as well as the other factors in traditional equation. Effect of each parameter on design radius was investigated for the case where the wind direction is acted with the same centrifugal force direction. It has been found that the required minimum radius increase with the decreasing of vehicle weight or in the other words the vehicle permitted speed decrease with the decreasing of vehicle weight. On the other hand, the required curve radius increases with vehicle height increasing. Consequently, permitted height of bags loaded on a truck is related to the type of loads. Derived equation can also be used for estimation of the permitted truck speed on existing roads especially in case of bad weathers The comparison between the traditional and suggested equation showed that maximum difference is about 160 % which results at high wind pressure while the difference is up to 20 % for low wind pressure
In the civil engineering, the prediction of cracks for tunnel lining is too hard because it depends by different factors for example concrete strength, tunnel operation conditions, stress and geological surroundings. The aim of this study is to design a Fuzzy inspect System (FIS) for evaluating the concrete cracks of tunnel lining. Fuzzy logic is a method to signify a type of uncertainty which is understandable for user. The system has been designed to meet permit crack formula that issued in “Highway Tunnel Design Specifications”. When the maximal permit crack width as example is chosen as 0.7mm, 1.2mm and 3.3mm separately the fuzziness set accordingly is Minor , moderate and severe. The average error for the predicted crack (element sample) in FIS is 8.34%. The fuzzy evaluation model is based on the information of a real in-service PESHRAW highway tunnel, which reflects field status. Therefore, this evaluation is comfortable.
Pavement rutting as a permanent deformation is a major type of distress in flexible pavements. In Iraq, the rutting in Expressway pavements represents a severe problem due to its widespread, and high severity and distress density levels. Therefore, driving is profoundly dangerous and causes severe damage to the vehicle’s parts and the life of its riders. To date, the number of comprehensive research on pavement rutting has been limited in Iraq, owing to several technical, logistic, and economic considerations. The current research studies the major mechanisms responsible for rutting and evaluates the structure of the Iraqi Expressway No.1 at selected sections. The work encompasses field and laboratory aspects. The field work involved; performing field surveys to investigate the pavement rutting condition and its extension with depth, characterizing pavement layers in terms of geometric material properties, and collecting field samples for lab tests. The laboratory work was detailed and included; performing a set of standard lab tests on samples taken from the asphalt, the subbase, and the subgrade layers as well as the natural ground. In addition, the project’s archive was searched for specific design information and limitations. In order to assess pavement rutting in the selected sections of Expressway No.1/R9 (A and B), two well-established evaluators were considered; The rutting severity levels and the distress density.
Crack monitoring of pavements is an ever-evolving technology with new crack identification technologies being introduced frequently. Although older technologies consisted of physical removing the pavement section using coring, however new methods are available that are non-destructive and yield a higher performance than conventional technologies. This paper compiles various crack monitoring technologies such as wireless sensor networks, photo imaging, laser imaging, 3D road surface profile scans, acoustics wave propagation technology, embedded strain sensors and onboard vehicle sensors that majorly use an artificial intelligence algorithm to identify and categorize the cracks. The research also includes the use of convolutional neural network that can be used to analyze pavement images and such neural network can localize and classify the cracks for crack initiation and propagation stage. The research concludes with the favor of using the optical imaging technology called Syncrack which serves better performance in terms of time of prediction by 25% and accuracy by 30% when compared to other sensing technologies.
This research includes producing compacted concrete by rolling method and the possibility for using in highway construction field with studying the influence of adding waste plastic fiber resulting from manual cutting for bottles used in the conservation gassy beverage on different characteristics of this type of concrete. For the purpose of selecting mix proportions appropriate for rolling compacted concrete (RCC). Approved design method for ACI-committee (5R-207 .1980) was selected for this research. Destroying plastic waste by volumetric rates ranging between (0.5%) to (2%) was approved. Reference mix was produced for comparison. Tests were conducted on the models produced from rolling compacted concrete like compressive strength, flexural strength and split tensile strength. The analysis of the results showed that the use of plastic waste fibers (1%) has led to improve the properties of each of the compressive strength and flexural strength and split tensile strength compared with reference concrete. Compressive strength in 28 days with fiber ratio (1%) is higher than (52.15%) from compressive strength in 28 days of reference concrete. It can be also observed that each of the flexural strength and split tensile strength increases by (17.86, 25.61)%, respectively, from flexural strength and split tensile strength for the reference mix