Conversation of at Grade Signalized Intersection in to Grade Separated Intersection

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1 IJIRST International Journal for Innovative Research in Science & Technology Volume 2 Issue 05 October 2015 ISSN (online): Conversation of at Grade Signalized Intersection in to Grade Separated Intersection Hiren Patel Assistant Professor Department of Civil Engineering SAL Institute of Technology and Engineering Research, Ahmedabad Abstract The urban traffic congestion has become a global phenomenon. Rapid urbanization and industrialization have caused an unprecedented revolution in growth of vehicles all over the world. This study presents, grade separation (over bridge) is provide in place of at grade signalized intersection. Ahmedabad city of Gujarat state is taken as study city. Shivaranjani signalized intersection on 132 ft ring road in the city of Ahmedabad is selected as a case study intersection. Various types of data are collected such as classified volume counts, signal cycle length, green time, phase plan etc. and number of lanes, lane width, grade, lane groups etc as a part of geometric data. The flow rate, saturation flow rate and its adjustment factors, capacity, volume to capacity ratio, critical lane group volume to capacity ratio, delay for lane groups, approaches and intersection as whole and delay comparison with level of service are calculated. This study proves that shivaranjani intersection must be required to convert in to grade separation. Keywords: Capacities, Congestion, Delay, Flow, Intersection, Lanes, Signal I. INTRODUCTION URBANIZATION In 1950, 30 % of world population lives in an urban area. In 2000, 47 % of world population lives in an urban area. These will increase up to 60 % in year This figures show that people want to live in an urban area. In India 30% of the population lives in urban area. In some progressive states like TamilNadu, it is 43.86%, second is Maharastra, it is more than 42%, and third is Gujarat, it is more than 37%. This urbanization is happen due to rapid industry growth and hence population density increased in cities. II. PROBLEM STATEMENT Rapid urbanization and industrialization have caused an unprecedented revolution in growth of vehicles all over the world. Due to fast growing vehicular traffic, cities become congested and road links, intersections become saturated, busy and supply service is above its capacity. This urban traffic congestion has become a global phenomenon. So, the problems at intersection are to require effective mode of controls to regulate the traffic and maintain optimum delay for congestion of the traffic on the intersection. III. OBJECTIVE Objective of this study is to please the conditions for conversation of at-grade signalized intersection in to grade separated intersection. A. Criteria for Provision of Grade Separated Intersection 1) Certain at-grade intersections which have reached the maximum capacity and where it is not possible to improve the capacity further by retaining the at-grade crossing. 2) At certain locations which have a proven record of bad accident history when functioning as at grade junctions. 3) At junctions where the traffic volume is heavy and the delays and loss caused justify economically the gradeseparation is provided. 4) Grade separation to be provided in urban street if the estimated traffic volumes within the next 5 years are in excess of the capacity of at-grade intersection. 5) Grade separation to be provided in urban street when traffic projections show that volumes within the next 20 years will exceed the capacity of at-grade intersection. 6) Volume to capacity ratio more than 1, grade separation should be provided. 7) Delay for lane groups, approaches as well as intersection as whole is unaccepted, grade separation should be provided. 8) LOS for lane groups, approaches and intersection as whole is unaccepted, grade separation should be provided. All rights reserved by 113

2 IV. METHODOLOGY FOR ANALYZING SIGNALIZED INTERSECTION A. Saturation Flow Rate Saturation flow rate is a basic parameter used to derive capacity. Saturation flow rate is computed for each of the lane groups. Saturation flow rate is calculated for prevailing conditions. A default value is selected for base saturation flow rate and it must be adjusted for a variety of factors that reflect geometric, traffic, and environmental conditions specific to the site under study. The saturation flow rate is the flow in vehicles per hour that can be accommodated by the lane group assuming that the green phase were displayed 100 percent of the time (i.e. g/c = 1.0). Saturation flow rate (s) for lane group is estimated by following equation: Saturation flow rate = (Base saturation flow rate) x (Numbers of lanes) x (Adjustment factors) B. Capacity Analysis The capacity of a given lane group may be stated as shown in equation: gi ci si C c i = capacity of lane group i (veh/h), s i = saturation flow rate for lane group i (veh/h), g i /C = effective green ratio for lane group i. C = cycle length (s). C. Volume to Capacity Ratio Analysis The ratio of flow rate to capacity (v/c), called the volume to capacity ratio. It is given the symbol X in intersection analysis. It is typically referred to as degree of saturation for a given lane group i, X i, X i = (v/c) i = ratio for lane group i, v i = actual or projected demand flow rate of lane group i (veh/h), C = cycle length (s). Xi v c D. Critical Volume to Capacity Ratio This is the v/c ratio for the intersection as a whole, considering only the lane groups that have the highest flow ratio (v/s) for a given signal phase. Generally one of two lane groups will require more green time than the other (i.e, it will have a higher flow ratio). This would be the critical lane group for that signal phase. V C X C S Ci C L Xc = critical v/c ratio for intersection; = summation of flow ratios for all critical lane groups i; C = cycle length (s); and L = total lost time per cycle, computed as lost time, t L, for critical path of movement (s). E. Delay Analysis The values derived from the delay calculations represent the average control delay. Control delay includes movements at slower speeds and stops on intersection approaches, such condition occurs when vehicles move up in queue position or slow down upstream of an intersection. Following equation used for control delay calculation. d = d 1 (PF) + d 2 + d 3, d = control delay per vehicle (s/veh), d 1 = uniform control delay (s/veh), PF = progression adjustment factors, d 2 = incremental delay (s/veh), d 3 = initial queue delay, (s/veh). i All rights reserved by 114

3 F. Aggregated Delay Estimates The procedure for delay estimation is the control delay per vehicle for each lane group. It is often desirable to aggregate these values to provide delay for an intersection approach and for the intersection as a whole. This aggregation is done by computing weighted averages, where the lane group delays are weighted by the flows in the lane groups. G. Approach Delay (d A ) d A = delay for Approach A (s/veh), d i = delay for lane group i (on Approach A) (s/veh), v i = flow for lane group i (veh/h) Intersection Delay (d I ) d I = delay per vehicle for intersection (s/veh) d A = delay for Approach A (s/veh), and v A = flow for Approach A (veh/h) d A = d I = divi v i d Av v A A H. Level of Service (LOS) Intersection LOS is directly related to the average control delay per vehicle. Once delays have been estimated for each lane group and aggregated for each approach and the intersection as a whole, following table is consulted, and the appropriate LOS is determined. Table - 1 LOS Criteria for Signalized Intersections LOS Control Delay per Vehicle (s/veh) A < 10 B >10-20 C >20-35 D >35-55 E >55-80 F >80 V. CASE STUDY SHIVARANJANI OVER BRIDGE Shivaranjani intersection peak hour volume is vehicles. Survey is carried out for 13 hours from morning 9:00 am up to night 22:00 pm. Geometric detailed is carried out from site for given intersection. Following are the steps for analyzing intersection for providing over bridge at Shivaranjani in table format. Table - 2 Saturation Flow Rate EAST APPROACH WEST APPROACH NORTH APPROACH SOUTH APPROACH Adjusted Factors LT TH RT LT TH RT LT TH RT LT TH RT Base Saturation Number of Lanes Lane Width Heavy Vehicle Grade Parking Bus Blockage Area Type All rights reserved by 115

4 Lane Utilization Left Turn Right Turn Right Turn ped/bike Left Turn ped/bike Adjusted Saturation Table - 3 Lane Group Capacity EAST APPROACH WEST APPROACH NORTH APPROACH SOUTH APPROACH LT TH RT LT TH RT LT TH RT LT TH RT V (veh/h) S (veh/h) t L (s) g (s) g/c C (veh/h) Table - 4 Lane Group Volume to Capacity Ratio EAST APPROACH WEST APPROACH NORTH APPROACH SOUTH APPROACH LT TH RT LT TH RT LT TH RT LT TH RT V (veh/h) C (veh/h) V/C Table - 5 Critical Lane Group per Phase PHASE 1 PHASE - 2 EAST WEST NORTH SOUTH TH RT TH RT TH RT TH RT V (veh/h) s (veh/s) v/s Critical lane group/ Phase (Y) (Y) (Y) (Y) Table - 6 Critical Flow Rate to Capacity Ratio, Xc, WEST SOUTH TH RT TH RT Critical lane group/phase (Y) (Y) (Y) (Y) Sum of critical v/s Total Lost Time 16 Critical Flow Rate/Capacity Ratio X C Table - 7 Lane Group Delay & LOS Analysis East Approach West Approach North Approach South Approach LT TH RT LT TH RT LT TH RT LT TH RT d1 (s/veh) K All rights reserved by 116

5 d2 (s/veh) d3 (s/veh) PF d (s/veh) LOS A F F A F F A F F A F F Table - 8 Approach Delay with LOS Analysis East and West Approach EAST WEST NORTH SOUTH Approach Delay Approach LOS F F F F Table - 9 Intersection Delay with LOS Analysis EAST WEST NORTH SOUTH Intersection Delay Intersection LOS F VI. RESULT ANALYSIS Following tables show the results for analysis intersection to providing over bridge at Shivaranjani. Table - 10 Capacity and Present Traffic Volume Approach Capacity (Veh/h) Present Traffic Volume (Veh/h) North South East West Intersection Total A. Comparison between Volume to Capacity Ratio and Flow Condition for Lane Groups There are three different conditions for measuring flow condition. These are: 1) When v/c ratio less than one, flow condition is under saturated 2) When v/c ratio equal to one, flow condition is saturated 3) When v/c ratio more than one, flow condition is over saturated Table - 11 v/c Ratio and Flow Condition for Lane Groups Approach Lane Group v/c Ratio Flow Condition LT Under Saturated Flow North TH Over Saturated Flow RT Over Saturated Flow LT Under Saturated Flow South TH Over Saturated Flow RT Over Saturated Flow LT Under Saturated Flow East TH Over Saturated Flow RT Over Saturated Flow LT Under Saturated Flow West TH Over Saturated Flow RT Over Saturated Flow B. Comparison between Critical Volume to Capacity Ratio for Intersection and Flow Condition There are three different conditions for measuring critical flow. These are: 1) When critical v/c ratio for intersection less than one, flow condition is under saturated 2) When critical v/c ratio for intersection equal to one, flow condition is saturated 3) When critical v/c ratio for intersection more than one, flow condition is over saturated All rights reserved by 117

6 There are four lane groups which behave as a critical lane group at Shivaranjani Intersection. They are: South approach through lane group South approach right turn lane group West approach through lane group West approach right turn lane group Table - 12 Critical v/c Ratio for Intersection and Flow Condition Conversation of at Grade Signalized Intersection in to Grade Separated Intersection Approach Lane Group Critical v/c Ratio Flow Condition South West TH RT TH Over Saturated Flow RT Table - 13 Delay and Level of Service for Lane Group Approach Lane Group Lane Group Delay (s/veh) Lane Group Level of Service North South East West LT 2.25 A TH F RT F LT 2.03 A TH F RT F LT 6.75 A TH F RT F LT 14.4 A TH F RT F Table - 14 Delay and Level of Service for Approach and Intersection Approach Delay (sec) Level of Service North F South F East F West F Intersection F VII. CONCLUSION A. Conclusion of Work The present traffic volume of shivaranjani intersection is more than present capacity of intersection. So grade separation to be provided. The v/c ratios for lane groups are unacceptable and all turning movements are protective phasing. So geometric changes will require. The critical v/c ratio for intersection as whole is greater than one. So intersection geometry changes will require. The delay for lane groups, approaches and intersection as whole are unacceptable and delay level of service is F. Hence, to convert the shivaranjani at grade intersection in to grade separated intersection. REFERENCES [1] Highway Capacity Manual, Transportation Research Board, National Research Council, Washington, D.C., 2000 [2] Subhash C. Saxena, A Course in Traffic Planning and Design, Dhanpat Rai Publication, Second Edition [3] S.K. Khanna and C.E.G. Justo, Highway Engineering, New Chand and Bros, Eight Edition, 2001, Roorkee [4] C. Jotin Khisty, Transportation Engineering an Introduction, Prentice Hall Englewood Cliffs, 1990, New Jersey [5] L.R. Kadiyali, Traffic Engineering And Transport Planning, Khanna Publishers, Sixth Reprint, 2004 [6] Chhanya Arun R, Adaptive Traffic Control Signal Design for an Isolated Intersection, 2004 All rights reserved by 118