CVE30003 Roundabout Exercise Single lane roundabout Inscribed diameter = 40 m Entry lane width = 4 m central island diameter = 30m + 2*5m for circulating road width No heavy vehicles Exercise. Solution Approach qe veh/h 1 N 410 qc qc 4+ t, pcu/h pcu/s s s 750 0.2083 2.23 3.87 ? ? ? Q veh/h s s 2.0 0.389 0.139 839 x 0.489 0.630 Interpolate 450.000 2.35 1 E 650 450 0.1250 2.35 4.24 2.0 0.577 0.096 1031 T in 510 675 0.1875 2.26 3.96 2.0 0.431 0.129 886 0.576 540.000 2.314 600.000 2.29 W 740 540 0.1500 2.31 4.13 2.0 0.515 0.110 971 from Table 1 from from Table 2 from formula Table 4 q2 is the entering flow (veh/h) qc is the circulating flow in conflict with the entering flow (converted to pcu/h) 3600 Q = (1 - 4 qc + 0.5 t, (qc)e- 2(tc- 4) tf For circulating flows at roundabouts P = 1 - (1 - ka) 4 qc 1- 4 qc Number of circulating D flow lanes 1 2 > 2 ka 2 2.2 1 = 1 2.2 0.8 2.2 Slightly different results are obtained if you use Table 3 instead of the formula for cp Exercise. Solution Approach qe veh/h qc pcu/h qc pcu/s tf s to ? s s ? ? 0.762 Q veh/h x N 1 E S W from Table 1 from from Table 2 Table 4 from Table 3 Table 1: Follow up heedway [sec]. ty Circulating Flow, q, Ipcu/h] 20 2.81 150 2.76 2.70 300 450 2.65 2.35 600 2.59 750 2.53 2.23 900 2.48 2.18 1050 2.12 1200 Table 2: Critical gap (sec), t. 2.36 2.07 Circulating Flow, q. [pcu/h) 20 0 5.51 4.93 150 5.2 4.68 300 5.01 450 4.79 4.74 600 4.58 4.05 750 4.39 3.87 900 4.21 3.70 1050 4.05 3.55 3.16 1200 3.90 Inscribed Diameter, D, [m] 4C 80 2.51 2.28 2.12 2.45 2.23 2.06 2.40 2.17 2.01 2.11 1.95 2.29 2.00 1.89 2.00 1.84 1.95 1.78 1.89 1.72 1.83 1.67 Inscribed Diameter, D, (m) 40 4.46 3.40 60 80 4.47 4.15 4.24 3.93 4.03 3.72 3.83 3.53 3,64 3.35 3.47 3.18 3.31 3.03 2.88 3.02 2.75