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PDF (DX094490.pdf) - White Rose Etheses Online

PDF (DX094490.pdf) - White Rose Etheses Online

1.1 Roundabout Design 1

1.1 Roundabout Design 1 Intersection control is one of the most important areas of traffic engineering theory and practice, as the per- formance of any road system and management scheme ultimately depends on the successful design of the intersections. The cheapest mode of control is the priority junction where one of the intersecting road flows has priority over the traffic on the other roads. This type is suitable for lcw flcws at the minor road. If the combination of the flows reaches certain critical values, the delays incurred by the minor road vehicles exceed acceptable limits. Then, alternative methods of control have to be installed. They include traffic signals, grade- separated layouts and roundabouts. The first gyratory systems were introduced in Paris in 1907 at the Place de l'Etoile and at the Place de la Nation. They were introduced in Britain in 1925, the Aidwych Island being one of the first in London. The initial mode of operation of roundabouts did not include a precise definition of the priority of any single stream of traffic at each entry. The two opposing streams were supposed to merge. In practice, however, one or the other of the streams sometimes established priority, forcing the opposing one to wait for suitable gaps in order to continue along its intended path. At high flows in more than one entry, therefore, it became possible for the roundabout to lock. The only solution to that problem, available at the time, was to increase the size of the roundabout, allowing more storage space between entries. The increase of cost associated with larger size layouts, and the decrease of sites that such layouts could be applied usefully, forced researchers to look to altern-

ative ways of improving the performance of roundabouts. 2 The turning point came in November 1966, when priority to the right was introduced at roundabouts in Britain. This measure prevented any locking, thus stabilizing the flows through the junction and reducing the delays. This allowed the develop- ment of design layouts not conforming to the pre-1966 conventions. Size was not significant any longer. It was established that smaller size islands and junctions did give improved perform- ances. New designs suggested include roundabouts with small and mini size islands, layouts incorporating more than one island, and wider entries at the stop line. This design implies that at the stop line there are more lanes for the queueing traffic than further back, on the approach road. However, the above new designs have not replaced completely the conventional large central island roundabouts, which still are used widely, especially at grade-separated intersections. More recently, traffic signals have been introduced in some sites to prevent very long queues and delays suffered in one, or more entries with very heavy flows when the circulating flow is also very heavy. 1.2 Roundabout Capacity Theory Before the introduction of the priority to the right rule at the roundabouts, their capacity was predicted using formul based on the proportion of the traffic weaving within each section. Since 1966, however, and the establishment of a clearly defined priority, weaving does not take place anymore. Up to 1975 the official design formula for conventional round- abouts was based on the weaving proportion; subsequently, however,

  • Page 1: A COMPUTER SIMULATION STUDY OF THE
  • Page 4 and 5: 11 SUMMARY This thesis reports on a
  • Page 6 and 7: iv TABLE OF CONTENTS Page No Acknow
  • Page 8 and 9: 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9
  • Page 10 and 11: viii LIST OF TABLES 3.1 Observed Fl
  • Page 14 and 15: 3 a modified formula was introduced
  • Page 16 and 17: CHAPTER 2 LITERATURE REVIEW: CAPACI
  • Page 18 and 19: (Wardrop, 1957). The investigation
  • Page 20 and 21: 9 They looked also at ways of impro
  • Page 22 and 23: 11 small-island layouts were design
  • Page 24 and 25: 13 operating under no clearly defin
  • Page 26 and 27: where a: the critical gap (sec), NQ
  • Page 28 and 29: where = Q e cx e -1 17 the maximum
  • Page 30 and 31: 19 The research carried out at TRRL
  • Page 32 and 33: take account of local operating con
  • Page 34 and 35: 23 These types are illustrated in f
  • Page 36 and 37: 25 exceeded by a considerable margi
  • Page 38 and 39: 27 queues at the end and beginning
  • Page 40 and 41: 29 TYPICAL CONVENTIONAL ROUNDABOUT
  • Page 43 and 44: EXAMPLE OF GRADE SEPARATED JUNCTION
  • Page 45 and 46: EXAMPLES OF MINI-ROUNDABOUT LAYOUTS
  • Page 47 and 48: "- C) 0 '.-. ) LU 0 S.- 0 C) ( j 0
  • Page 49 and 50: 38 CHAPTER 3 COLLECTION 0F DATA
  • Page 51 and 52: 40 Sheffield. It was observed that,
  • Page 53 and 54: 42 using a SONY AV342OCE portable m
  • Page 55 and 56: 44 Ecciesall Road. However, this di
  • Page 57 and 58: 46 TABLE 3.2 Day Entry Total flow F
  • Page 59 and 60: \\ Ec.esa11 Road \"\\/i? LLjji 1lTh
  • Page 61 and 62: \\\\\ ' \\\\ r * ' \\\_\ ' ' \\% .'
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    61 CHAPTER 4 GAP ACCEPTANCE CHARACT

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    63 this field. The conventions used

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    65 have been developed that use mor

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    67 of drivers who accept such gaps,

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    69 consistently accept all gaps gre

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    71 a merging platoon. Although they

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    73 They related the gap-acceptance

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    75 advance which rejected gaps shcu

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    77 proposed by Bennett (1971), Horm

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    larger than the respective ones for

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    81 The direct linear relationship i

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    83 mean squared errors or variances

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    85 produce reasonable predictions,

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    87 the rejected gaps. The results o

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    89 exclusion of top values decrease

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    91 definition of gap size as depend

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    93 4.5.8 The Effect of Assuming the

  • Page 97 and 98:

    95 demonstrated on Fig. 4.8 and Fig

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    97 When the model was validated by

  • Page 101 and 102:

    99 4.8.2.2 The Negative Exponential

  • Page 103 and 104:

    101 0: the proportion of restrained

  • Page 105 and 106:

    103 coefficient of the regression s

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    105 From the point of view of which

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    107 TABLE 4.1 (continued) No.1 Loca

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    Cl U) a) a) 0 I )1) H U) 0 U) a) '-

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    1 2 3 4 56789 10 2.95 2.94 2.68 2.9

  • Page 115 and 116:

    Ci) (ii) 0. 113 TABLE 4.7 mean st.d

  • Page 117 and 118:

    1 2 345678 9 0 2.42 2.44 2.50 2.63

  • Page 119 and 120:

    1 2 3 4 5 6 7 8 9 10 2.61 2.93 2.68

  • Page 121 and 122:

    (i) (ii) a 119 TABLE 4.13 mean st.d

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    oup 121 TABLE 4.16 no.of entries on

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    1 2 3 4 5 67 8 9 10 11 12 13 14 15

  • Page 127 and 128:

    1 2 3 4 5 6 7 8 9 10 125 TABLE 4.21

  • Page 129 and 130:

    4i -1 0 '-I- U-I a) .li.IC 127 E- .

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    129 TABLE 4.26 Time interval- (sec)

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    No. of passing vehicles 0. 1 2 3 4

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    ci) 4) x4-4 ..-..' .,-4 CDV) U H N

  • Page 137 and 138:

    250 200 50 I00 50 135 o i 6 7 8 9 1

  • Page 139 and 140:

    tag ..engfñLf Weaving Width •3/

  • Page 141 and 142:

    0 0 1, 0 C- 4.5 4. 0 3. 5 3. 0 2.5

  • Page 143 and 144:

    3. 5 3. 0 2.5 0 0 2. 0 1.5 141 1.5

  • Page 145 and 146:

    U, II 114 U z isa 114 Ii. z 0 U) (/

  • Page 147 and 148:

    145 CHAPTER 5 THE SIMULATION PROGRA

  • Page 149 and 150:

    147 following a uniform (rectangula

  • Page 151 and 152:

    149 Let F(t) = r, the random fracti

  • Page 153 and 154:

    151 5. Entering or alternatively up

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    153 (b) Three initial numbers for t

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    155 vehicles are not of such length

  • Page 159 and 160:

    U U, a Ia- LO 0.9 0.8 07 0.5 - 0.4.

  • Page 161 and 162:

    159 CHAPTER 6 RESULTS AND COMMENTS

  • Page 163 and 164:

    161 equivalent to the capacity of a

  • Page 165 and 166:

    163 parameters. It was found that a

  • Page 167 and 168:

    165 least 50% straight ahead traffi

  • Page 169 and 170:

    167 left-turning vehicles, is not u

  • Page 171 and 172:

    169 exhibit a minimum average delay

  • Page 173 and 174:

    171 not operating at or near capaci

  • Page 175 and 176:

    Input 500 1000 1500 2000 2500 3000

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    4000 3500 3000 L 2500 N -c > ..2000

  • Page 179 and 180:

    177 1. Ashworth and Laurence (1977)

  • Page 181 and 182:

    (0 C -J Lj_ o L 0 -a 3 z > 4.0 3. 5

  • Page 183 and 184:

    C.. -C N-c > 1000 980 960 940 920 9

  • Page 185 and 186:

    0 1 U- uJ 540 520 500 480 183 0. 0

  • Page 187 and 188:

    N > 0 -J IL > C- C ILl 0 200 160 16

  • Page 189 and 190:

    C) Co 6 4 >2 -J a m C.. 0 > -I 8 18

  • Page 191 and 192:

    C, Co >\ CD 0 CD CD S 15 10 189 % S

  • Page 193 and 194:

    C) •1 > 0 L. > 10 5 191 ST 101 =

  • Page 195 and 196:

    U (0 >.' -J C, (I > -J 20 10 193 %

  • Page 197 and 198:

    ' -J a m C.. > 10 5 195 Qi = 500 ve

  • Page 199 and 200:

    0 CD CD Ii >\ CD CD CD CD C.. CD >

  • Page 201 and 202:

    0 (U (U (U Cj (U (U > -J (U 20 10 0

  • Page 203 and 204:

    0 I. >' Oi C.. > -J 0 '-0 30 20 10

  • Page 205 and 206:

    0 60 40 IT 203 cx = 2.50 sec 500 =

  • Page 207 and 208:

    C) (0 60 40 20 205 02 = 3.50 sec c.

  • Page 209 and 210:

    t!) 60 40 >20 207 Beta 01 = 1000 ve

  • Page 211 and 212:

    0 0 60 40 120 209 Beta Q1 = 3000 ve

  • Page 213 and 214:

    .0 60 40 11 1.5 211 Alpha Q1 = 1000

  • Page 215 and 216:

    C) Co 60 40 20 213 ALpha Q1 = 3000

  • Page 217 and 218:

    215 A computer simulation model has

  • Page 219 and 220:

    217 hou1d. Therefore any change in

  • Page 221 and 222:

    219 Ashworth, R. and M.Z.H. Mattar,

  • Page 223 and 224:

    221 Kirnber, R.M. and E.M. Hollis,

  • Page 225 and 226:

    223 Wagner, F.A., 1966. "An Evaluat

  • Page 227 and 228:

    7 0 4 225 0 4 20 24 F re A. 1 Qb.er

  • Page 229 and 230:

    4-. C'- -7 227 0 4 12 20 24 -. z ec

  • Page 231 and 232:

    DOUBLE PRECISION R INTEGER*4 I A =

  • Page 233 and 234:

    231 GPNO(i13) = GPNO(K3)+1 NOG GPNO

  • Page 235 and 236:

    43 121(SX,A1) 12 IF (A1.GE.AP) AX =

  • Page 237 and 238:

    235 DELY(H2,M3) T3(i12,N3)-121(112,

  • Page 239 and 240:

    82 2 237 sui entries of lane tar

  • Page 241 and 242:

    108 106 CONTINUE 109 CONTINUE DO 10

  • Page 243 and 244:

    CAP CAP+CA(N3) 125 CONTINUE 00 128

  • Page 245 and 246:

    ci) 0 ci) a) '-I 0 a) 0 4-1 in 4-1

  • Page 247 and 248:

    I-i a) 0 ci) a) $4 a) L;l 4-I 0 -'-

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