Situation B – Roads carrying larger vehicles#
For temporary alignments where traffic includes a higher percentage of heavy vehicles and vehicles larger than a semi-trailer, projects typically apply lane and edge clearances more in accordance with permanent road design guidelines for lane widths and the barrier offsets in accordance with the Queensland MUTCD/QGTTM. Application of the Main Roads WA guidance for barrier offsets results in identical cross section reduction for each speed as detailed in Table 4.1.3.3(b) but with wider lane widths.
4.1.3.4Two-lane, one-way carriageway#
For temporary alignments where at least two lanes are maintained in a single direction, and in situations where traffic is made up of light vehicles and heavy vehicles no larger than a semi-trailer, projects typically apply lane and edge clearances in accordance with the Transport and Main Roads Queensland MUTCD Part 3. This then leads to a minimum cross-section for a two-lane two-way temporary road as detailed in Table 4.1.3.4(a).
| Speed (km/h) | Lane width (m) | Lane width (m) | Edge Clearance (m) | Total width (m) |
|---|---|---|---|---|
| 40 | 3.0 | 3.0 | 0.3 | 6.6 |
| 60 | 3.0 | 3.0 | 0.5 | 7.0 |
| 80 | 3.5 | 3.5 | 0.5 | 8.0 |
In this situation, there may be applications for the use of lane widths narrower than those specified in the Queensland MUTCD Part 3. A potential design exception that could be considered would be reducing one lane in each direction on multi-lane roads to a width below the 3.0 m minimum specified for a posted speed of 60 km/h, or below the 3.5 m width specified for 80 km/h. At least one remaining lane in each direction on these multi-lane temporary alignments should be maintained at the widths specified in the Queensland MUTCD Part 3 to accommodate heavy vehicles. In association with these reduced lane widths, it may also be possible to consider reduced edge clearances in line with those documented in the Main Roads WA guidelines. This then results in the comparative cross section widths detailed in Table 4.1.3.4(b).
| Speed (km/h) | Lane width (m) | Lane width (m) | Edge Clearance (m) | Total width (m) | Cross section reduction compared to Table 4.1.3.4(a) (m) |
|---|---|---|---|---|---|
| 40 | 3.09 | 2.75 | 0.2 | 6.15 | 0.45 |
| 60 | 3.0 | 2.75 | 0.3 | 6.35 | 0.65 |
| 80 | 3.5 | 2.75 | 0.5 | 7.2 | 0.75 |
Where wider lanes are required for vehicles larger than a semi-trailer, the Lane Width specified for Lane 2 and the edge clearances could potentially be reduced in line with the dimensions detailed in Table 4.1.3.4(b).
