Highway Engineering

116 Highway Engineering

Example 5.2 Contd

Parameters D,Eand F:

Capacities:

m

m

m

ba

bc

cb

pcu/hr

pcu/hr

pcu/hr

=-{}[]()+ ()+ ()+ ()

=

=-{}[]()()+ ()

=

=-¥[]()()+

=

077 627 06 70 364 619 0 114 169 0 229 844 0 520 84

234

082 745 067 0364 619 0 114 169

477

081745 0 364 0 67 619 169

448

... ...

....

...

D

E

F

Y

=+[]()- []+-()[]+-()=

=+[]()- []+-()=

=+[]()- []+-()=

10 094 2 5 3 65 1 0 0009 30 120 1 0 0006 50 150 0 77

10 094 2 5 3 65 1 0 0009 30 120 0 82

10 094 2 2 36 5 1 0 0009 50 120 0 81

......

.....

.....

==-[]() 10 ()...345 9 5¥ = 067

Ratios of flow to capacity (RFC):

For the most critical movement (traffic exiting onto the major road, turning

right) the ratio is just below the maximum allowed in urban areas of 0.85.

The maximum reduces to 0.75 in rural areas.

Stream Flow (pcu/hr) Capacity (pcu/hr) RFC

qba 197 234 0.84

qbc 141 477 0.30

qcb 84 448 0.19

Table 5.1RFCs for

opposed flow

movements

Queue length at stream B-A:

L =0.5 ¥((A^2 +B)1/2-A)

Assuming random arrivals (therefore C =1)

A=(1 -r)mt + 1 - L 0

B =4(L 0 +rmt)

r=0.84

m=234 pcu/hr

t =1 hour

L 0 =0 (no cars waiting at start of time period)

Contd