Highway Engineering

(5.1)

(5.2)

(5.3)

In these equations the stream capacities and flows are measured in passenger
car units per hour.
The geometric characteristics of the junction, represented in Equations 5.1 to
5.3 by D,Eand Fand specific to each opposed traffic stream, are represented as:

Parameters:
m= Stream capacity
qab =Measured flow of stream a-b
qac =Measured flow of stream a-c
qca =Measured flow of stream c-a
qcb =Measured flow of stream c-b
wba =Average lane width over a distance of 20 m available to waiting vehicles
in the stream b-a, metres
wbc =Average lane width over a distance of 20 m available to waiting vehicles
in the stream b-c, metres
wcb =Average lane width available to waiting vehicles in the stream c-b, metres
Vrba=Visibility to the right from a point 10 m back from the give-way line for
vehicles making the b-a manoeuvre, metres
Vlba=Visibility to the left from a point 10 m back from the give-way line for
vehicles making the b-a manoeuvre, metres

D

E

F

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

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

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

10094 3 65 1 0 0009 120 1 0 0006 150

10094 3 65 1 0 0009 120

10094 3 65 1 0 0009 120

....

...

...

wVrVl

wVr

wVr

ba ba ba

bc bc

cb cb

mcb=-FY()745 0 364. []qqac+ab

mbc=-EY() 745 []0 364..qqac+0 114ab

mba=+-DWY()627 14 cr []0 364....qqqqac+ + +0 114 ab 0 229ca 0 520cb

The Design of Highway Intersections 111

B

qba

qac

qab

qcb

qca

qbc

C A

Figure 5.12Relevant flows for determining capacity of major movements through
priority intersections.