Evaluation of Main Roundabouts of Kurukshetra *G Veerababu * P.G.Student Dept. of Civil Engineering, NIT Kurukshetra, Kurukshetra, Haryana, India. Abstract Traffic rotary is a specialized form of at-grade intersection where vehicles from the converging arms are forced to move round an island in one direction in an orderly and regimented manner and weave out of the rotary movement into their desired directions. The main aim of a roundabout is to eliminate the necessity stopping even for crossing streams of vehicles and to reduce the area of conflict. The objective of this paper is to bring out the design aspects used in different countries for roundabouts. In this paper capacity of Main roundabouts of Kurukshetra has determined by IRC model as well as by other countries models and also in this paper comparison of these calculated capacities has done. In this paper Evaluation of roundabouts of Kurukshetra has done based upon capacity and actual traffic volume during peak hour and finally suggested measures to improve these roundabouts. Keywords: Roundabout, Intersection, traffic, Capacity,IRC model Introduction: Roundabouts are a type of circular intersection or junction in which road traffic flows continuously in one direction around a central island.with the rapid growth of traffic it is experienced that widening of roads and providing flyovers have become imperative to overcome major conflicts at intersections such as collisions between through and right turn movements. In this way, major conflicts are converted into milder conflicts like merging and diverging. The vehicles entering the rotary are gently forced to move in a clockwise direction. Roundabouts are the efficient intersection design over the signalized intersections depending upon traffic and site data. Depending on the size of circular traffic intersections it may be classified as Rotary, Roundabout and Mini-roundabout. Rotaries are suitable when there are more approaches and no separate lanes are available for right turn traffic thus making the intersection geometry complex. Rotaries were designed in the 1940 s or earlier and work well at low volumes, but very poorly under heavy traffic conditions. Under low traffic conditions, a roundabout offers higher capacity as compared to a two-way stopped control or an all-way stop-controlled intersection. Roundabouts were developed in the 1960 s and able to handle heavy traffic. Mini-roundabouts are best suited to areas with low speeds and there is no feasibility to use roundabout with a raised central island. Mini-roundabouts are common in the United Kingdom (U.K.), France, United State and Germany since their introduction in the early 1970 s. Literature Review: The researchers have focused on the relationship between geometric design and traffic conditions for achieving the required operational performance of roundabouts. IRC:65-1976(Recommended practice for traffic rotaries) lays down the guiding principles governing the design of traffic rotaries. S.K. Mahajan, et al. (2013) A new geometric concept is discussed to design rotaries at intersection of roads and a software package is developed to be used in road works. A design manual for Roads and Bridges (TD 16/07) sets out the design standards and advice for the design of roundabouts. Satish Chandra and Rajat Rastogi(2012) proposed a simple empirical method to determine the entry capacity from the flow conditions alone after comparing the results of the UK model, US method, German Model, Swiss model and Indian model. S.Vasantha Kumar1, et al.(2014) Attempt to find the capacity of the complex intersection with many one way approaches. R.AKCELIC (2003) This paper presents a single lane roundabout case study from the US to compare capacity estimates from the analytical models. BRUCE W. ROBINSON et al. a comprehensive discussion of roundabout planning, Performance analysis and design. Ramu Arroju1,et al. (2015) The capacity of the roundabout is determined using various capacity formulae. Serhan Tanyel1, et al.(2005) In this study, the applicability of the Highway Capacity Manual 2000 HCM 2000 Procedure for 526 G Veerababu
roundabouts in Turkey is discussed. Mark Lenters et al. July (2010) an alternative technique to adapt the U.K. empirical model to the design implications of the recent U.S. data. CAPACITY MOELS OF ROUNDABOUT INDIAN CAPACITY MODEL (IRC: 65-1976) 527 G Veerababu Q p = 280 w 1 + e w 1 p 3 1 + w l Where Q p = Practical capacity of the weaving section of the rotary in passenger car units (PCU) per hour w = Width of weaving section in metres(within the range of 6-18m) e = Average entry width in metres (i.e., average of e 1 and e 2 ), e to be within a range of 0.4 to 1.00 w l = Length in metres of the weaving section between the ends of channelizing islands( w to be within the range l of 0.12 and 0.40) p = Proportion of weaving traffic, i.e., ratio of sum of crossing streams to the total traffic on the weaving b+c section ( p = ), range of p being 0.4 to 1.0 a+b+c+d a = left turning traffic moving along left extreme lane b = crossing/weaving traffic turning towards right while entering the rotary c = crossing/weaving traffic turning towards left while leaving the rotary d = right turning traffic moving along right extreme lane UK CAPACITY MODEL (Kimber, 1980) q e,max = k(f f c q c ) Where, q e,max = entry capacity (veh/h) q c = circulating flow (veh/h) F = 303 x 2 f c = 0.21 T D (1 + 0.2 x 2 ) k = 1 0.00347(Ф 30) 0.978(1/r 0.05) T D = 1 + 0.5 1+exp D 60 10 x 2 = entry adjustment factor = v + e v 1+2S S = e v l e = entry width(m) ranging from 3.6 to 16.5 v = approach half-width(m) ranging from 1.9 to 12.5 l = effective flare length(m) ranging from 1 to r = entry radius(m) ranging from 3.4 to Ф = entry angle ( ) ranging from 0 to 77 S = measure of the degree of flaring ranging from 0 to 2.9 D = inscribed circle diameter(m) ranging from 13.5 to 171.6 US METHOD (HCM 2000): C = Q Ce Q c Tc /3600 1 e Q ct f /3600 C = approach capacity (veh/h) Q c = conflicting circulating traffic (veh/h) T c = critical gap(s) T f = follow up time(s)
Proposed Capacity Model 1 (PM 1) The model depends upon the width of weaving section, proportion of vehicle and number of vehicles entering into the road in consideration as given in Equation (4.10). The model is developed considering the IRC:65-1976 capacity formula. Passenger Car Unit (PCU) value of different type of vehicles are taken according to IRC:65-1976. Q P = 300W V P E R Where, Q P = Capacity of Roundabout (pcu/h) W = Circulating Carriageway Width (m) No.of Veicles entering from te road in consideration V P = Vehicle Proportion = Total no.of veicles entering from all roads to te intersection E R = No. of vehicles entering from the road in consideration (pcu/h) Proposed Capacity Model 2 (PM 2) The model depends upon the width of weaving section, entry width and inscribed circle diameter. The model is developed considering the IRC:65-1976 capacity formula as explained in Equation (4.11). Q P = 215(e + w)log 2D Where, Q P = Capacity of Roundabout (pcu/h) e = Average Entry Width (m) w = Width of Weaving Section (m) D = Inscribed Circle Diameter (m) e + w CAPACITY CALCULATION: TABLE-1 Traffic in Vehicles per Hour (Ambedkar chowk) Type Traffic of From Kessel Mall side (A) From Birla Mandir side (B) From side (C) Market From Pipli Side (D) L S R L S R L S R L S R Total Vehicles Buses/Trucks 0 0 0 2 38 2 0 0 0 4 30 0 76 2.8 PCU Value Rickshaw 0 12 2 8 4 0 0 12 6 4 14 4 66 1.5 Tractortrailer 0 0 0 0 22 4 0 0 0 2 22 2 52 2.8 Cars 4 8 2 20 326 16 6 12 6 46 412 20 878 1 3-W 2 4 6 14 234 0 30 0 12 12 310 8 632 1 2-W 8 246 70 76 536 60 132 336 144 172 516 102 2398 0.75 Cycles 0 54 4 6 28 8 12 78 6 24 22 2 244 0.5 ADV 0 0 2 4 0 0 0 0 0 4 0 0 10 4 Total 14 324 86 130 1188 90 180 438 174 268 1326 138 4356 528 G Veerababu
TABLE-2 Traffic in Vehicles per Hour (Visvkarma Chowk) From Pipli Side From Birla Mandir side From Jhansa side Type of Total PCU (A) (B) (C) Traffic Vehicles Value L S R L S R L S R Buses/Trucks 8 0 0 2 0 30 0 12 2 64 2.8 Rickshaw 2 24 0 6 0 4 0 26 14 76 1.5 Tractor-trailer 0 2 0 6 0 2 0 8 0 18 2.8 Cars 206 168 0 86 0 396 0 220 44 1120 1 3-W 106 66 0 42 0 224 0 112 8 564 1 2-W 266 458 0 376 0 440 0 550 154 2244 0.75 Cycles 10 28 0 20 0 6 0 38 16 118 0.5 ADV 0 0 0 0 0 0 0 0 0 0 4 Total 598 762 0 538 0 1102 0 966 238 4204 TABLE-3 Traffic in Vehicles per Hour (Near 3r Gate KUK) From Railway From Birla From Opposite to Type of Total PCU track side (A) Mandir side (B) Birla mandir side (C) Traffic Vehicles Value L S R L S R L S R Buses/Trucks 28 0 0 0 36 32 0 36 0 132 2.8 Rickshaw 8 0 4 0 4 16 0 0 0 32 1.5 Tractortrailer 16 0 4 0 4 8 0 12 0 44 2.8 Cars 276 0 8 0 208 176 20 276 0 964 1 3-W 92 0 0 0 40 52 12 40 0 236 1 2-W 660 0 76 0 236 280 40 444 0 1736 0.75 Cycles 60 0 4 0 8 36 0 16 0 124 0.5 ADV 4 0 0 0 0 0 0 0 0 0 4 Total 1144 0 96 0 536 600 72 824 0 3272 TABLE-4: Geometric Details of Selected Roundabouts of Kurukshetra Geometric parameters 1.Ambedkar Chowk 2.visvkarma chowk Central Island (m) 12 12 - Inscribed Diameter (m) circle 33 33 - Entry Width (m) 8 8 6 Exit width (m) 8 8 6 Approach width (m) 7.5 7.5 7.5 Departure width (m) 7.5 7.5 7.5 Circulating road width (m) 8 8 - Entry radius (m) 30 30 25 Exit radius (m) 30 30 25 3.3 rd Gate KUK 529 G Veerababu
Table-5: Volume Data Collected for different Roundabouts Roundabout Direction Entry Volume (vph) Total Volume (vph) LT ST RT 1.Ambedkar Chowk 2.visvkarma chowk AB 14 324 86 424 BC 130 1188 90 1408 CD 180 438 174 792 DA 268 1326 138 1732 AB 598 762 0 1360 BC 538 0 1102 1640 CA 0 966 238 1204 3.3 rd Gate KUK AB 1144 0 96 1240 BC 0 536 600 1136 CA 72 824 0 896 Table-6: Capacity Estimated by Different Methods for Roundabouts Roundabout Direction Entry Capacity(pcu/h) by UK Method IRC Method PM1 PM2 1.Ambedkar Chowk 2.visvkarma chowk AB 1202 2622 2973 BC 2105 2685 2529 CD 1394 2685 2908 DA 2015 2749 2314 AB 2062 3337 2615 2209 BC 1721 3453 2401 2209 CA 1438 2745 2705 3.3 rd Gate KUK AB BC CA Can t apply any formula 530 G Veerababu
CAPACITY (PCU/H) CAPACITY (PCU/H) International Journal of Engineering Technology, Management and Applied Sciences 3500 3000 2500 2000 1500 1000 500 UK Method IRC Method PM1 PM2 0 AB BC CD DA ROUNDABOUT Fig.1. Comparison of Capacity Models(Ambedkar chowk) 4000 3500 3000 2500 2000 1500 1000 UK Method IRC Method PM1 PM2 500 0 AB BC CA ROUNDABOUT Fig.2. Comparison of Capacity Models(Visvkarma chowk) 531 G Veerababu
CAPACITY (PCU/H) International Journal of Engineering Technology, Management and Applied Sciences 2950 Central island vs Capacity by IRC 2900 2850 2800 2750 2700 2650 2600 0 2 4 6 8 10 12 14 CENTRAL ISLAND DIA (m) Fig.3 Variation of Capacity with respect to Central Island Diameter for constant Inscribed Circle Diameter CONCLUSION The variations of capacity among different models have shown in Table 6 and graphically in fig.1.among different capacity models, UK method gives lower capacity whereas the Indian method (IRC:65-1976) gives higher capacity.from this we can conclude that UK method is lower estimating and IRC method is over estimating the capacity.the capacity estimated by Propsosed models (PM1 & PM2) ) values nearer to IRC model and lies in between UK models and IRC model. As the second model depends upon only geometry data so the capacity value is same for both roundabout 1 and roundabout 2.Since the shape of Roundabout 3 is non circular we cannot use any of the above models.to increase the capacity and to give some more space for large vehicles like buses and trucks,central Island Diameter maybe has to decrease for Ambedkar chowk and for Visvkarma chowk no need to decrease the central island diameter.oval shape roundabout is may be suitable near 3 rd gate. REFERENCES Indian Road Congress, IRC:65-1976 Recommended Practice for Traffic Rotaries BRUCE W. ROBINSON LEE A. RODEGERDTS, Capacity and Performance of Roundabouts: A Summary of Recommendations in the FHWA Roundabout Guide Ramu Arroju1,Hari Krishna Gaddam1, Comparative evaluation of roundabout capacities under heterogeneous traffic conditions Serhan Tanyel1; Türkay Baran2; and Mustafa, Determining the Capacity of Single-Lane Roundabouts in Izmir, Turkey Mark Lenters et al. july 2010, HCM Roundabout Capacity Methods and Alternative Capacity Models S. Vasantha Kumar et al.,2014, Capacity Estimation of a Complex Rotary Intersection with Many one Way Approaches-A case study R.AKCELIC(2003), A Roundabout case study comparing capacity Estimates from Alternative Analytical Models Satish Chandra & Rajat Rastogi, 2012, Mixed Traffic Flow Analysis on Roundabouts S.K. Mahajan, et al. 2013 New Concept of Traffic Rotary Design at Road Intersections 532 G Veerababu