Traffic Engineering Correspondence

Table 7          Sensitivity Analysis (Heavy Vehicle Growth Rate)

    Heavy Vehicle Growth Rate                                    1                                                          2
                                               DESA (ESA’s)                                DG20HM Thickness (mm)
    (%)

    2                                          135 million                                 335

    4                                          240 million                                 365

    6                                          440 million                                 405
    Notes: 1. DESA based on 40 year design life.
           2. Includes 10 mm construction tolerance.


A change in growth rate from 2 % to 6 % resulted in a difference in asphalt thickness of 70 mm, which
could have a significant impact on the overall cost of the project.

Opening Year AADT
A sensitivity analysis was carried out to determine the impact of a change in the opening year traffic along
the Bruce Highway. The opening traffic adopted for the detailed pavement designs were varied by varied
by 15 % to determine the impact on the pavement design traffic and the base layer thickness of a typical
full depth asphalt pavement configuration and subgrade condition. The results are summarised in Table 8.

Table 8          Sensitivity Analysis (Opening Year AADT)
                                                                1                                                       2
    Opening Year AADT                         DESA (ESA’s)                                DG20HM Thickness (mm)

    18,700 (-15 %)                            245 million                                 370

    22,000 (detailed design)                  285 million                                 375

    25,300 (+15 %)                            330 million                                 385
    Notes: 1. DESA based on 40 years design life.
           2. Includes 10 mm construction tolerance.


The sensitivity analysis indicates that a 15 % change in the opening year AADT is unlikely to have a
significant impact on the asphalt thickness of the pavements.


3.2           Local Roads

3.2.1         Traffic Input Parameters
The traffic data used for the pavement design of the local roads was based on the following sources of
information:
                                                                         (2)
       Traffic Analysis Report prepared by GHD (GHD, 2010                     )
       Sunshine Coast Regional Council Planning Scheme, Policy 5 (SCRC, 2005)
       Updated traffic figures prepared by GHD in 2012
       Construction traffic estimates prepared by GHD in 2012
The traffic input parameters adopted for the pavement designs of the local roads are summarised in
Table 9.

41/24401/11/437270     Bruce Highway (Cooroy to Curra) Upgrade Section A (Cooroy Southern Interchange - Sankeys Road)           10
                       Job No. 263/10A/12, Invitation No. NCHD-2454
                       Pavement Design Report