Basic Elements of Highway Traffic Analysis 95
Example 4.7 Contd
LGV:
High growth 2002–2006 = 1350 ¥(1 +0.0258)^4 = 1495
Low growth 2002–2006 = 1350 ¥(1 +0.0193)^4 = 1457
OGV1:
High growth 2002–2006 = 600 ¥(1 +0.0107)^4 = 626
Low growth 2002–2006 = 600 ¥(1 +0.0043)^4 = 610
OGV2:
High growth 2002–2006 = 450 ¥(1 +0.0285)^4 = 504
Low growth 2002–2006 = 450 ¥(1 +0.0221)^4 = 491
PSV:
High growth 2002–2006 = 150 ¥(1 +0.0098)^4 = 156
Low growth 2002–2006 = 150 ¥(1+0.0034)^4 = 152
Therefore:
AADT 2006 (high forecast) =13 450 + 1495 + 625 + 505 + 155 =16 231
AADT 2006 (low forecast) =13 115 + 1457 + 610 + 491 + 152 =15 825
(Giving a high growth rate over the four years of 8.2% and a low rate of
5.5%)
Table 4.12 shows that a wide single carriageway (2 ¥5.0 m) with a range
of 10 000 to 18 000 is the most appropriate standard. The high forecast brings
the flows just over the upper limit for a standard 7.3 m wide single carriage-
way road (maximum capacity =16 000)
4.6 The UK approach for urban roads,
4.6.1 Introduction
The advice note TA 79/99 Traffic Capacity of Urban Roads(DoT, 1999) gives
the maximum hourly flows for different highway categories. The maximum flows
can be used as starting points in the design and evaluation of new proposed
urban links. These capacities can also be utilised as a guide for assessing the ade-
quacy of existing urban highways and the effect that any changes to their basic
features (such as carriageway width) will have on the safe and efficient opera-
tion of the highway. It should be noted that, as with the assessment of rural
links, both economic and environmental considerations must be taken into con-
sideration before a final decision is made.
