Highway Engineering

94 Highway Engineering

2002–2006 2007–2011 2012–2016

Low High Low High Low High

Cars 1.31 1.95 1.11 1.76 1.01 1.67

LGV 1.93 2.58 1.82 2.48 1.92 2.59

OGV 1 0.43 1.07 0.46 1.10 0.55 1.20

OGV 2 2.21 2.85 2.09 2.74 2.15 2.82

PSV 0.34 0.98 0.34 0.99 0.41 1.07

2017–2021 2022–2026 2027–2031

Low High Low High Low High

Cars 0.64 1.31 0.30 0.98 0.28 0.97

LGV 1.83 2.51 1.67 2.36 1.49 2.19

OGV 1 0.57 1.24 0.60 1.29 0.60 1.30

OGV 2 2.01 2.69 1.89 2.58 1.73 2.44

PSV 0.50 1.17 0.59 1.27 0.66 1.36

Table 4.13Low and

high growth forecasts

for five different

categories of road

traffic (DoT, 1997b)

Cars LGV OGV1 OGV2 PSV

0.83 0.09 0.04 0.03 0.01

Table 4.14Percentage

of different vehicle

classes in UK for 1994

(DoT, 1996)

Example 4.7

A highway is due to open on the first day of 2006. On 1 January 2002 the

traffic flow was measured at an equivalent AADT of 15 000. On the basis of

the forecasted AADT range in the opening year, select the appropriate rural

road classification.

Assuming that the vehicular traffic is composed of the above five categories

(car, LGV, OGV1, OGV2, PSV) calculate the AADT for the year after

opening (2006) using the high and low growth estimates.

Solution

15 000 vehicles:


 12 450 cars


 1350 LGV


 600 OGV1


 450 OGV2


 150 PSV

Cars:

High growth 2002–2006 =12 450 ¥(1 +0.0195)^4 =13 450

Low growth 2002–2006 =12 450 ¥(1 +0.0131)^4 = 13115

Contd