فرايند ارزيابي اقتصادي و بهينه سازي در ايم نسازي مشخصه هاي هندسي راه

Economic Appraisal and Optimization Process in Road Geometric Safety Improvements

در تصمي مگيري براي بهين هسازي طرحهاي ايمن سازي راه لازم است فرآيندي منظم براي انتخاب مناس بترين اقدامات در قالب هر پروژه مشخص پي شبيني مي شود. با استفاده از مدل ارايه شده، بودجه مشخصي كه از جانب دولت در اختيار سازمان مسيول قرار گرفته است بين تمامي موقعيتهاي از پيش تعيين شده راه به نحوي توزيع مي شود كه: ) 1( با استفاده از سهم تعلق گرفته به هر موقعيت مكاني، بهترين اصلاحات ممكن در چارچوب يك راهكار برتر از بين چند راهكار انتخاب شود، به طوري كه بهترين منفعت خالص را نتيجه دهد و در نهايت مجموع منافع خالص در تمامي موقعيتها به حداكثر مقدار خود برسد و ) 2( مجموع هزينه هاي ساخت مربوط به راهكارهاي انتخاب شده در تمامي موقعيتهاي مكاني از بودجه كل بيشتر نشود. جوانب هندسي و محيطي مورد بررسي در اين تحقيق شامل مطالعه عرض خط تردد، نواحي خطر كناره راه، قوسهاي افقي، قوسهاي قايم و پلهاي ك معرض است. در تشكيل اين فرآيند از روش تحليل هزينه- فايده براي ارزيابي اقتصادي و از روش برنامه ريزي عدد صحيح صفر- يك براي روند بهينه سازي استفاده شده است. در نهايت فرآيندي 8 مرحل هاي ارايه مي شود كه در آن شناسايي، ارزش گذاري، تنزيل و مقايسه منافع و هزينه ها شرح داده شده است.

For making decisions in optimizing investments in road safety projects, it is required to establish a regular process for selecting the most suitable countermeasures to be provided to road safety planners and decision-makers. Using the model developed in this research, a given budget funded from the road agency may be distributed among all predetermined locations (sites or routes), considering: (1) applying the share assigned to each location, the best possible improvements are selected as the premiere strategy amongst all alternatives through which the highest benefit is resulted, and finally, the sum of net benefits for all locations is maximized, and (2) the sum of construction costs attributed to selected alternatives in all locations does not exceed the total project budget. A set of road safety measures is studied involving the items known as geometric features and road design criteria. The features defined here consists of lane width and road surface quality, roadside hazard zones, horizontal curves, crest vertical curves and narrow bridges. The cost-benefit analysis and binary integer programming methods are used to develop economic appraisal and complete optimization tasks. The Solver program (as an add-in to Excel) is the main tool to run the allocating process. The research economic appraisal and optimization process consist of eight steps within which some criteria are applied to define, valuate, discount and compare the cost and benefit components of the analysis. The most important measure to estimate the safety benefits is a mediator variable which is broadly known as Accident Modification Factor (AMF). In this research, AMFs are extracted for each geometric feature mentioned above using the current valid accident models in Iran. As a means to support the execution of the developed model, a software program contributing to running the process of resource allocation is provided.