Appendix C Worked Examples
Five design examples are described to show typical designs for determining rates of application of binder and aggregate spread rates. These examples cover:
- single/single reseal on a heavily trafficked rural highway
- double/double reseal carrying a high percentage of heavy vehicles
- single/single strain alleviating membrane (SAM) reseal
- geoxtextile reinforced seal (GRS)
- quarry access road.
These cover a range of traffic volumes and highlight the various adjustments and allowances that should be taken into consideration, as well as the calculations that must be carried out to determine the binder design application rate and aggregate spread rate.
Attention to detail is most important to ensure the design being prepared is appropriate to the job conditions. Some common errors observed in the design process, which directly affect the rates and therefore the outcome and performance of the sprayed seal are:
- insufficient attention being given to obtaining the latest traffic volumes required to determine the appropriate design traffic, particularly on the more complex and/or multi-lane situations
- not checking that the aggregate details provided by the supplier are relevant and apply to the aggregate being used on the job.