左弯待转区.ppt

Analysis on Waiting Area for Left-turn Vehicles at Signalized Intersections Yongheng Chen, PhD Transportation Colloege Jilin University The People’s Republic of China cyh2009@163.com JILIN UNIVERSITY Outline What’s WAFLT Left-turn spillback After setting WAFLT Timing condition JILIN UNIVERSITY What’s WAFLT A new type of channelization Increasing use Lack of methods to design and analyze them JILIN UNIVERSITY WAFLT The rule of WAFLT Lagging protected left-turn phase When the green time of through phase begins at the same approach, the left-turn vehicles start to run into the waiting area for left-turn and wait to complete their turning movement in green time for left-turn. JILIN UNIVERSITY WAFLT JILIN UNIVERSITY The contrast of non-spillback and spillback at approach A JILIN UNIVERSITY Left-turn queue accumulation polygon (case 1) The queue of left-turn vehicles overflows the left-turn lane during tr time. JILIN UNIVERSITY Left-turn queue accumulation polygon (case 2) The queue of left-turn vehicles overflows the left-turn lane during gT time. JILIN UNIVERSITY Left-turn queue accumulation polygon (case 3) There is no spillback occurred. JILIN UNIVERSITY The change after setting WAFLT Case1 Case2 Case3 Case4 JILIN UNIVERSITY The sketch of conflict points JILIN UNIVERSITY Timing condition（绿尾滞留） For conflict point 1 For conflict point 2 Minimum green time JILIN UNIVERSITY Longer signal interval time New condition E N D THANK YOU JILIN UNIVERSITY Case 1 Before the left-turn vehicles overflow the left-turn lane, the left-turn queue forming during tr has started into the waiting area, which indicates that the capacity of left-turn lane increases to N*. Meanwhile, due to N*≥Q2, the queue of left-turn does not spill back and other vehicles release smoothly during the gT time. The spillback problem is solved by setting WAFLT. Case 2 However, due to N*Q2 the left-turn queue overflows the left-turn lane after t*u. The duration of left-turn spillba