An Investigation to Determine the Minimum Acceptable Roadway Condition for Iran's Highways

To properly plan for construction, repair, maintenance, and reconstruction ofhighways theminimum acceptable roadway condition is needed information. this, along with other pavementmanagement tools, will help select the most desirable roadway alternatives. in this research theminimum acceptable conditions are developed based on an opinion survey of non-technical buthigh-level decision makers. roadway roughness, expressed as international roughness index (iri),is used as the measurement criteria. because iri is a widely known, acceptable, and a uniformlymeasurable index, it is used for the purpose of this research. the minimum iri values developedhere will help managers, planners, and engineers in prioritizing their plans and projects. iran hasa central planning system, hence having a minimum acceptable iri will help in producinghomogeneity in decision making. a questionnaire is sent to top level and influential managementlevelofficials who have a decisive input in highway matters. the officials are asked to choose theminimum acceptable service level of different types of roadways and classifications. naturally,roadways with higher levels ofimportance would require higher service levels. the answers to thesurvey questionnaires are investigated to determine a preferred minimum acceptable roadwaycondition. the iri is computed using a mechanical device enabling a more uniform data collection.the iri was first proposed by the world bank as a standard roughness statistic. extensive researchhas proven that the iri can be related to pavement condition. the result of the opinion survey isinvestigated to determine the minimum levels acceptable for each category. the responses showdistinct preference patterns for most ofthe roadway types. survey results are investigated by plottingand analyzing them. based on road user sperception of roadway condition using guidelines fromaashto, the corp ofengineers, and related research work. the appropriate iri limits and rangesare determined for iran shighways. these values are adjusted to obtain final values for iran. theresult, shown in a table, gives upper and lower iri values accepted and recommended for iran shighways. the result ofthis research work is specifically useful in developing specifications for newpavement design, accepting new pavement from contractors, pavement management, highwayplanning, and in roadway life cycle cost analysis decision making. the results are subject torefinement over time.