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�e <br />TO: Jim Davis, <br />Public Works Director <br />FROM: Mike Orr, <br />;Traffic Engineer <br />F ��� <br />DATE: <br />October 27, 1981 <br />bfT+�`_ O CTS ^ " G�, <br />/, 190 <br />� 'din ''r''•• <br />SUBJECT. <br />Corridor Study Des <br />REFERENCES: <br />Attached is a work progress schedule chart for a corridor study. The <br />chart graphically illustrates the time frame and study process dependencies <br />required to conduct an engineering study. <br />The initial work phase is called inventory, which consists of gathering data <br />on the road being studied. Data in the form of traffic counts, collision dia- <br />grams, existing traffic control devices, and intersection movements is obtained <br />manually and using special equipment. Time is the dependent varible for data <br />generation - for example, useful traffic volume figures are based upon counts <br />taken over a seven-day period at a single location. Therefore, for a complex <br />corridor study requiring many volume figures, weeks or months are necessary to <br />obtain these counts. <br />Likewise, the second phase, ANALYSIS, is dependent upon an outside variable. <br />In this instance, not time, but the data generated in the Inventory phase is <br />required before a proper engineering analysis of roadway adequacy can begin. The <br />schedule chart illustrates these dependencces between data generation and time, <br />and analysis and data. The Analysis process compares data generated during the <br />Inventory with nationally accepted.standards for roadway- characteristics (e.g. <br />traffic control, accidents, speeds, -capacity, number of lanes). These standards <br />consist of policy statements, threshold figures, rates of occurance, and pro- <br />cedures. <br />Once analysis is complete for the roadway in question, a preliminary RECO',1- <br />MENDATION for improvements needed, if any, can be made. However, only after this <br />three-phase process (Inventoi-y-Analysis-Reconunendation) is completed for all <br />roadway corridors in the study area can a single, coordinated, "master plan" for <br />traffic circulation be presented. This is due to the dynamic, interdependent, <br />and synergistic characteristics of the traffic system. For example,- one roadway <br />cannot be changed without affecting another roadway. Also, if improvements are <br />made between interconnected roadways treated as a system, benefits usually are <br />greater than if.treated separately. <br />W1. <br />BOOR 48 PACE 47 <br />