Evaluation of Main Roundabouts of Kurukshetra - IJETMASijetmas.com/admin/resources/project/paper/f201704241493023517.pdf · move round an island in one direction in an ... = Practical

International Journal of Engineering Technology, Management and Applied Sciences

www.ijetmas.com April 2017, Volume 5, Issue 4, ISSN 2349-4476

526 G Veerababu

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



527 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)

Qp = 280 𝑤 1 +

𝑒𝑤 1 −

𝑝3

1 +𝑤𝑙

Where

Qp = 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 „e1‟ and „e2‟ ), 𝑒

𝑤 to be within a range of 0.4 to 1.00

l = Length in metres of the weaving section between the ends of channelizing islands(𝑤

𝑙 to be within the range

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

section ( p = 𝑏+𝑐

𝑎+𝑏+𝑐+𝑑 ), range of p being 0.4 to 1.0

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)

𝑞𝑒 ,𝑚𝑎𝑥 = 𝑘(𝐹 − 𝑓𝑐𝑞𝑐)

Where,

qe,max = entry capacity (veh/h)

qc = circulating flow (veh/h)

F = 303 x2

fc = 0.21 TD (1 + 0.2 x2)

k = 1 – 0.00347(Ф – 30) – 0.978(1/r – 0.05)

TD = 1 + 0.5

1+exp 𝐷−60

10

x2 = 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 = 𝑄𝐶𝑒

−𝑄𝑐𝑇𝑐/3600

1−𝑒−𝑄𝑐𝑇𝑓/3600

C = approach capacity (veh/h)

Qc = conflicting circulating traffic (veh/h)

Tc = critical gap(s)

Tf = follow up time(s)



528 G Veerababu

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.

𝑄𝑃 = 300𝑊 − 𝑉𝑃 × 𝐸𝑅

Where,

QP = Capacity of Roundabout (pcu/h)

W = Circulating Carriageway Width (m)

VP = Vehicle Proportion = 𝑁𝑜 .𝑜𝑓 𝑉𝑒𝑕𝑖𝑐𝑙𝑒𝑠 𝑒𝑛𝑡𝑒𝑟𝑖𝑛𝑔 𝑓𝑟𝑜𝑚 𝑡𝑕𝑒 𝑟𝑜𝑎𝑑 𝑖𝑛 𝑐𝑜𝑛𝑠𝑖𝑑𝑒𝑟𝑎𝑡𝑖𝑜𝑛

𝑇𝑜𝑡𝑎𝑙 𝑛𝑜 .𝑜𝑓 𝑣𝑒𝑕𝑖𝑐𝑙𝑒𝑠 𝑒𝑛𝑡𝑒𝑟𝑖𝑛𝑔 𝑓𝑟𝑜𝑚 𝑎𝑙𝑙 𝑟𝑜𝑎𝑑𝑠 𝑡𝑜 𝑡𝑕𝑒 𝑖𝑛𝑡𝑒𝑟𝑠𝑒𝑐𝑡𝑖𝑜𝑛

ER = 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).

𝑄𝑃 = 215(𝑒 + 𝑤)log 2𝐷

𝑒 + 𝑤

Where,

QP = Capacity of Roundabout (pcu/h)

e = Average Entry Width (m)

w = Width of Weaving Section (m)

D = Inscribed Circle Diameter (m)

CAPACITY CALCULATION:

TABLE-1 Traffic in Vehicles per Hour (Ambedkar chowk)

Type of

Traffic

From Kessel

Mall side (A)

From Birla

Mandir side (B)

From Market

side (C)

From Pipli Side

(D) Total

Vehicles

PCU

Value

L S R L S R L S R L S R

Buses/Trucks 0 0 0 2 38 2 0 0 0 4 30 0 76 2.8

Rickshaw 0 12 2 8 4

0 0 12 6 4 14 4 66 1.5

Tractor-

trailer 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



529 G Veerababu

TABLE-2 Traffic in Vehicles per Hour (Visvkarma Chowk)

Type of

Traffic

From Pipli Side

(A)

From Birla Mandir side

(B)

From Jhansa side

(C) Total

Vehicles

PCU

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)

Type of

Traffic

From Railway

track side (A)

From Birla

Mandir side (B)

From Opposite to

Birla mandir side (C) Total

Vehicles

PCU

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

Tractor-

trailer 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 3.3rd

Gate KUK

Central Island (m) 12 12 -

Inscribed circle

Diameter (m)

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



530 G Veerababu

Table-5: Volume Data Collected for different Roundabouts

Roundabout Direction Entry Volume (vph) Total Volume

(vph) LT ST RT

1.Ambedkar

Chowk

AB 14 324 86 424

BC 130 1188 90 1408

CD 180 438 174 792

DA 268 1326 138 1732

2.visvkarma

chowk

AB 598 762 0 1360

BC 538 0 1102 1640

CA 0 966 238 1204

3.3rd

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

AB 1202 2622 2973

2209 BC 2105 2685 2529

CD 1394 2685 2908

DA 2015 2749 2314

2.visvkarma

chowk

AB 2062 3337 2615

2209 BC 1721

3453 2401

CA 1438 2745 2705

3.3rd

Gate

KUK

AB

Can‟t apply any formula BC

CA



531 G Veerababu

Fig.1. Comparison of Capacity Models(Ambedkar chowk)

Fig.2. Comparison of Capacity Models(Visvkarma chowk)

0

500

1000

1500

2000

2500

3000

3500

AB BC CD DA

CA

PA

CIT

Y (

PC

U/H

)

ROUNDABOUT

UK Method

IRC Method

PM1

PM2

0

500

1000

1500

2000

2500

3000

3500

4000

AB BC CA

CA

PA

CIT

Y (

PC

U/H

)

ROUNDABOUT

UK Method

IRC Method

PM1

PM2



532 G Veerababu

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 3rd

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”

2600

2650

2700

2750

2800

2850

2900

2950

0 2 4 6 8 10 12 14

CA

PA

CIT

Y (

PC

U/H

)

CENTRAL ISLAND DIA (m)

Central island vs Capacity by IRC

Documents

Evaluation of Main Roundabouts of Kurukshetra - IJETMASijetmas.com/admin/resources/project/paper/f201704241493023517.pdf · move round an island in one direction in an ... = Practical