Main flexible pavement and mix design methods in Europe and challenges for the development of an european method

Pavement and mix design represent one of the key components within the life cycle of a road infrastructure, with links to political, economic, technical, societal and environmental issues. Recent researches related to the characteristics of materials and associated behavior models both for materials and pavement, made it appropriate to consider updating current pavement design methods, and especially in the USA this has already been in process while in Europe uses of the methods developed in the early 1970s. Thus, this paper firstly presents a brief historical overview of pavement design methods, highlighting early limitations of old empirical methods. Afterwards, French, UK and Shell methods currently in use in Europe will be presented, underlining their main components in terms of methodology, traffic, climatic conditions and subgrade. The asphalt mix design and modeling in Europe are presented with their inclusion in the pavement design methods. Finally, the main challenges for the development of a European pavement design method are presented as well as the recent research developments that can be used for that methodThe second author would like to express the support of Portuguese National Funding Agency for Science, Research and Technology (FCT) through scholarship SFRH/BSAB/114415/ 2016. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.info:eu-repo/semantics/publishedVersio

Highway Construction Materials From the Consolidated Rocks of Southwestern Iowa

Southwestern Iowa, unlike other parts of the State, does not have plentiful near-surface supplies of stone available for highway construction purposes. The long and intensive search for such road material by quarrymen, highway engineers, geologists, and others interested in all phases of stone use resulted in a growing conviction that the only hope of locating new and significant deposits lay in a regional geological survey. Further, such a survey would result in the delineation of areas where exploration should be economically feasible as well as those areas where exploration would have little or no chance of success. These views formed the foundation for de-veloping the project covered by this report under a cooperative agreement with the Iowa Highway Research Board of the Iowa State Highway Commission. The aims of the project were (1) to locate and describe all consolidated rocks found in place at the surface, or penetrated by drilling or other means; (2) to correlate these rocks geologically; (3) to assemble this information and the valid geological inferences from it into cross sections and maps showing the type of bedrock, thickness of overburden and rock structure; and (4) to write appropriate comments so that the potential usefulness and the most promising sites for future exploration or expansion for stone quarries can be readily seen and be of maximum value. The report was prepared with the knowledge that its chief immediate use would be by highway engineers and geologists, county engineers, materials producers, and prospectors. To facilitate their use of the report, certain phases were stressed and some standard methods of presentation and arrangement were not rigidly followed. The scientific integrity of the report is not compromised by these deviations from the formal scientific writing practices, nor is the value of the report for other uses thereby lessened

Use of speed profile as surrogate measure: Effect of traffic calming devices on crosstown road safety performance

Urban road safety management is usually characterized by the lack of sufficient, good quality crash data and low budgets to obtain it even though many traffic accidents occur there. For example, 54 percent of road crashes in Spain take place in urban areas, and 10 percent of urban fatal crashes occur on crosstown roads, which are rural roads that traverse small communities. Traffic calming measures (TCMs) are often implemented on these parts of rural roads that traverse small communities in order to reduce both the frequency and severity of crashes by lowering speeds, but evaluation of their effectiveness has been limited. The objective of this study was to develop a methodology using continuous speed profiles to evaluate the safety effectiveness of TCMs on crosstown roads as part of an integrated system in the absence of historical data. Given the strong relationship between speed and crash experience, safety performance can be related to speed. Consequently, speed can be used indirectly as a surrogate safety measure in the absence of crash and speed data. Two indexes were defined in this study as surrogate safety measures based on the continuous speed profile: Ra and Ea. Ra represents the absolute accumulated speed variations relative to the average speed and is inversely related to accumulated speed uniformity; and Ea represents the accumulated speed variations above the speed limit and is directly related to accumulated speeding. Naturalistic data were collected using GPS trackers for 12 scenarios with different TCM spacings. Then, the indexes were applied to individual observed speed profiles (individual analysis) as well as the operating speed profile (global analysis). The values obtained from individual and global analysis were statistically different. Spacing lower than 110 m, which was found optimal from previous research, did not allow drivers to modify their speeds as the accumulated speed uniformity was quite similar regardless of the average operating speed; and, accumulated speeding was also minimized. Consequently, the scenarios where the TCMs were implemented according to the technical criteria presented a better design quality. On the other hand, age and gender differences did not seem to affect the average speeds or the accumulated speed uniformity and accumulated speeding.Moreno Chou, AT.; García García, A. (2013). Use of speed profile as surrogate measure: Effect of traffic calming devices on crosstown road safety performance. Accident Analysis and Prevention. 61:23-32. doi:10.1016/j.aap.2012.10.013S23326

Metric Plan Reading Course

This Plan Reading Course was developed by the Department of Civil and Construction Engineering of Iowa State University under contract with the Iowa Highway Research' Board, Project HR-324. It is intended to be an instructional tool for Iowa Department of Transportation (DOT), county and municipal employees within the state of Iowa. Under this contract, a previous Plan Reading Course, prepared for the Iowa State Highway Commission in 1965, has been completely revised using a new format, new plans, updated specifications, and new material. This course is a self-taught course consisting of two parts; Highway Plans, and Bridge and Culvert Plans. Each part consists of a self-instruction book, a set of plans, a question booklet, and an answer booklet. This is the self-instruction book for the Bridge and Culvert Plans part of the course. The example structures included in this part of the course are a prestressed concrete beam bridge and a reinforced concrete box culvert. The accompanying plans for those structures are: BRIDGE ON U.S. 65 - OVER RELOCATED U.S. 18 - This is a 70.5 m x 27.3 m pretensioned, prestressed concrete beam bridge in Cerro Gordo County, Design No. 1895, September 1996; and REINF. CONC. BOX CULVERT, 2.4 m x 1.5 m x 66.2 m, Cerro Gordo County, Design No. 895, April 1996

Subgrade Insulation to Prevent Soil Freezing

This report concerns the use of thermal insulation under rigid pavement. It is recognized that the desirability of preventing soil freezing applies equally to the supporting subgrade for flexible pavement. The exact placement of the insulation under either type of pavement will depend upon individual job requirements and the ingenuity of the designer. It should be kept in mind that the installation method and its compatibility with standard construction procedures is an important factor in the cost of the project. If the installation method is complicated, it will likewise be costly. In this event, the use of thermal insulation may not prove economical in comparison with the conventional practice of replacing the frost-susceptible subgrade soil with granular material

Roadside development; a selected bibliography annotated.

Includes index.Mode of access: Internet