مقايسه عملكرد ترافيكي، مصرف سوخت، و آلايندگي تقاطع داراي چراغ و دوربرگردان در بزرگراه هاي شش-خطه

Evaluation of Operations, Fuel Consumption, and Emission at Signalized Intersections Replaced by U-Turns along Six-Lane Highways

دورﺑﺮﮔﺮدان، ﺑﻪ ﻋﻨﻮان اﺑﺰاري ﻣﻬﻢ و ﻏﯿﺮﻣﺘﻌﺎرف ﺑﺮاي ﺑﻬﺒﻮد ﻋﻤﻠﮑﺮد ﺑﺰرﮔﺮاهﻫﺎ ﺑﻪ ﮐﺎر ﻣﯽرود. در ﺑﺮﺧﯽ ﺷﻬﺮﻫﺎي اﯾﺮان، دورﺑﺮﮔﺮدان ﺑﺎ ﻃﺮﺣﯽ ﻣﺘﻔﺎوت از اﻧﻮاع ﻣﺸﺎﺑﻪ ﺧﻮد، ﺑﻪ ﻣﻨﻈﻮر رواﻧﯽ ﺗﺮدد ﺑﺰرﮔﺮاهﻫﺎ، ﺟﺎﯾﮕﺰﯾﻦ ﭼﺮاغ راﻫﻨﻤﺎﯾﯽ ﺷﺪ. ﺗﺤﻘﯿﻘﺎت ﭘﯿﺸﯿﻦ ﺑﺮاي ارزﯾﺎﺑﯽ ﻋﻤﻠﮑﺮد دورﺑﺮﮔﺮدان، ﻧﺘﺎﯾﺠﯽ ﻫﻤﺴﻮ ﻧﺪاﺷﺖ ﭼﻮن ﺗﺤﻠﯿﻞﻫﺎ روﺷﻤﻨﺪ ﻧﺒﻮده، ارزﯾﺎﺑﯽ در دوره اوج و ﻏﯿﺮ اوج اﻧﺠﺎم ﻧﺸﺪه، ﺑﺮآﯾﻨﺪ دو اﺛﺮ ﺣﺬف ﭼﺮاغ و ﭘﯿﻤﻮدن ﻣﺴﺎﻓﺖ اﺿﺎﻓﻪ ﺑﺮاي دور زدن ﺑﻪ ﺻﻮرت ﻫﻢزﻣﺎن ﺑﺮرﺳﯽ ﻧﺸﺪه اﺳﺖ. ﺑﻨﺎﺑﺮاﯾﻦ، ﭘﺮوژهاي ﻣﻄﺎﻟﻌﺎﺗﯽ ﺑﺮاي ارزﯾﺎﺑﯽ ﻋﻤﻠﮑﺮد دورﺑﺮﮔﺮدان ﺗﻌﺮﯾﻒ ﺷﺪ. ﺑﺮاي ﻣﻘﺎﯾﺴﻪ، از ﺷﺒﯿﻪﺳﺎزي ﺗﻘﺎﻃﻊ ﭼﺮاغدار و ﻣﺪلﺳﺎزي رﯾﺎﺿﯽ زﻣﺎن و ﺳﺮﻋﺖ ﺳﻔﺮ ﺣﺮﮐﺎت دورﺑﺮﮔﺮدان ﺑﻬﺮهﺑﺮداري ﺷﺪ. ﻧﺘﺎﯾﺞ ﺗﺤﻘﯿﻖ ﻧﺸﺎن داد در دوره ﺗﺮدد ﺳﻨﮕﯿﻦ و ﻣﺘﻮﺳﻂ، دورﺑﺮﮔﺮدان ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﻗﺎﺑﻞﺗﻮﺟﻪ زﻣﺎن ﺳﻔﺮ، اﻓﺰاﯾﺶ ﺳﺮﻋﺖ ﺳﻔﺮ، ﮐﺎﻫﺶ ﻣﺼﺮف ﺳﻮﺧﺖ ﻣﯽﺷﻮد. وﻟﯽ در دوره ﺗﺮدد ﺳﺒﮏ ﻋﻤﻠﮑﺮد آن ﻣﻨﻔﯽ ﻫﺴﺖ. در دو ﺗﻘﺎﻃﻊ ﮔﻠﺒﺮگ- ﺑﺎﻗﺮي و رﺳﺎﻟﺖ- ﺑﺎﻗﺮي در ﺗﻬﺮان(، ﺑﺮآﯾﻨﺪ ﻋﻤﻠﮑﺮد 24 ﺳﺎﻋﺘﻪ دورﺑﺮﮔﺮدان از ﺑﺎﺑﺖ ﺗﺮاﻓﯿﮑﯽ و ﻣﺼﺮف ﺳﻮﺧﺖ، ﻣﺜﺒﺖ ارزﯾﺎﺑﯽ ﻣﯽﺷﻮد. ﺗﻘﺎﻃﻊ داراي دورﺑﺮﮔﺮدان، ﺗﻮﻟﯿﺪ روزاﻧﻪ آﻻﯾﻨﺪهﻫﺎيCO و HC را ﮐﺎﻫﺶ و ﺗﻮﻟﯿﺪ NOX را اﻓﺰاﯾﺶ ﻣﯽدﻫﺪ. از ﻣﻌﺎﯾﺐ دورﺑﺮﮔﺮدان اﯾﻦ اﺳﺖ ﮐﻪ اﺣﺘﻤﺎل ﺑﺮﺧﻮرد ﺑﺎ اﺟﺰاء ﻫﻨﺪﺳﯽ دورﺑﺮﮔﺮدان ﺑﺎﻻﺳﺖ. ﻫﻤﭽﻨﯿﻦ، دورﺑﺮﮔﺮدان اﺛﺮات ﻣﻨﻔﯽ ﻈﯿﺮ اﻓﺰاﯾﺶ ﻣﺼﺮف ﺳﻮﺧﺖ، ﻣﺴﺎﻓﺖ ﺳﻔﺮ( ﺑﺮاي ﺧﻮدروﻫﺎي ﻣﻌﺒﺮ ﻓﺮﻋﯽ دارد. ﻫﺮﭼﻪ ﻧﺴﺒﺖ ﺣﺠﻢ ﮔﺮدﺷﯽ ﺑﻪ ﺣﺠﻢ ﻣﺴﺘﻘﯿﻢ رو ﺑﺰرﮔﺮاه اﻓﺰاﯾﺶ ﯾﺎﺑﺪ، دورﺑﺮﮔﺮدان ﺗﻮان ﺑﯿﺸﺘﺮي در اﻓﺰاﯾﺶ رواﻧﯽ ﺗﺮدد ﺑﺰرﮔﺮاه دارد

U-Turns are an important and unconventional tools for the improvement of highway operations. In some cities of Iran, signalized intersections were replaced by mid-block median u-turns which have different design from foreign counterparts. Recent studies on the performance of u-turns led to controversial results since they did not apply systematic approach for accurate evaluation, studies were not conducted for peak and nonpeak periods, and the resultant effects of eliminating delays at the intersection and spending more time for making a u-turn were not considered simultaneously. Therefore a research was conducted in which operations of signalized intersection were simulated and operational models were deployed to obtain travel times and speeds at u-turns. At high and medium volumes, u-turns increase travel speed of vehicles by 20 (km/h) and decrease speed by 10 (km/h) at low volumes. As the volume ratio of turning vehicles to highway through vehicles rises, u-turns ability to improve highway mobility rises. At Bagheri-Golbarg and Bagheri-Resalt intersections (in Tehran), fuel consumption declines by 1,623 and 4,244 liters per day, although minor street vehicles daily consumption rises by 1,269 liters. The daily emission of CO and HC declines and NOX emission grows. In brief, u-turns have strong performance at high and medium volumes and poor performance at low volumes while it may have some negative impacts on minor street vehicles. There is high risk of collision with geometric elements of u-turns. This result is in concordance with studies that state total amount of crashes increase by 13.2 percent at u-turns.