FLH PDDM Chapter 9 - Eastern Federal Lands Highway Division

9.4.A. Geometric Design. (continued)subsurface. Their purpose is to extend the service life, provide additional pavement strength, restore orimprove the original cross section, improve the ride of the roadway, and enhance safety. An RRR projectshould not decrease the existing geometrics of the roadway section. See TRB Special Report 214, DesigningSafer Roads for additional information.Funding restrictions may prevent improvement of existing highways to the desirable standards. Therefore,when the pavement condition reaches minimal service level, there is a need for cost effective pavement andimprovement projects.RRR projects reflect and emphasize the economic management of the highway system. Therefore, economicconsiderations will largely determine the scope of work.Many factors influence the scope of a RRR project, such as the following:Roadside conditionsFunding constraintsEnvironmental concernsChanging traffic and land use patternsPavement conditionAccident dataAcquisition of additional right-of-way to construct RRR improvements is sometimes necessary. Horizontaland vertical alignment modifications, if any, should be minor.The Designer should review the project in the field and include those items that will be practical enhancementsto the project. These items may include the following:Roadside obstacle removalDrainage improvementsSlope rounding or flatteningTraffic barrierTraffic control devicesShoulder improvementsMinor wideningBridge railsIntersection improvementsRailroad-crossing improvementsIlluminationMany of these work items will enhance the project by providing the broadest scope of improvementpossibilities.Carefully establish project limits, particularly where widening occurs. Avoid ending the project at potentiallyhazardous locations, such as a narrow structure or a severe vertical or horizontal curvature. Provide theappropriate safety measures when these conditions are unavoidable.All safety elements of an RRR project merit specific consideration. Collect and analyze accident numbers,types, and rates for the project to identify safety problem areas. In addition, field reviews can identifypotentially hazardous conditions.9 - 55