UNIVERSITY OF TECHNOLOGY, SYDNEY SUBJECT 49106 - ROAD ENGINEERING PRACTICE FLEXIBLE PAVEMENT DESIGN BITUMEN SEALING DRAINAGE ASSIGNMENT 2 Autumn 2017 Due 28 May 2017 ROADS ENGINEERING PRACTICE 49106 FLEXIBLE PAVEMENT, BITUMEN SEALING and DRAINAGE DESIGN ASSIGNMENT Question 1 (4 marks) a) Benkelman Beam testing on the subgrade has the following results: a. Mean CBR = 6.7 b. Standard deviation = 0.7 c. Calculate the coefficient of variation, and the characteristic CBR if the proposed road has an AADT> 2000 and is not a major highway or motorway. b) For a new road that is to be constructed, describe how you would determine the design subgrade strength (CBR) at the appropriate subgrade moisture content. Question 2 (4 marks) A section of local access road (no buses) in a country town is being considered for reconstruction. A traffic count has provided the following data:- AADT (total for two lanes) 800 vpd Growth rate 2.0 % pa Commercial vehicles 8 % Calculate the Design number of Standard Axle Repetitions for a design period of 20 years. If the growth rate is actually 3% and the heavy vehicle percentage is actually 12%, calculate the design ESAs and comment on the effect these changes would have on the pavement thickness. Use figure 12.2, Table 12.2 and assume a CBR of 5. Question 3 (5 marks) a) After a carriageway is widened, the surface drainage has the following characteristics: Drainage path = 25 metres Slope= 3.7% Rainfall intensity = 50 mm/h The pavement is concrete with a hessian drag finish Calculate the water film depth and comment on its acceptability. How would you reduce the water film depth if required? b) Explain the concept of the major and minor drainage system approach Question 4 (4 marks) A section of rural 2-lane road has a pavement in poor condition. It is proposed to leave the alignment unchanged. Options for its reconstruction or rehabilitation are being considered. The following information is available:- Subgrade CBR 4 Characteristic deflection 1.2 mm Characteristic curvature 0.25mm Design traffic loading 5 x 105 ESA (a) The rehabilitation option is granular overlay with a sprayed seal. Design the pavement thickness for this option. (b) The proposed reconstruction is the construction of a new granular pavement option. Design the total pavement thickness and layer thicknesses for this option, assuming that it will be surfaced with a sprayed seal plus 30mm of asphalt. Question 5 (3 marks) A section of road has been reconstructed. It has a granular pavement and the traffic on the road is 3,000 vpd/lane with 8% heavy vehicles. You have the following materials available for sealing of the road:- • Cutback bitumen binder • Class 170 bitumen and cutter oil • Adhesion agent (1% additive) • 7mm nominal size crushed aggregate, ALD 4mm, precoated and free of moisture, absorption value <1%, angular average shape • 14mm nom. size crushed aggregate, ALD 8.5mm, precoated and free of moisture, absorption value <1%, angular average shape At least 12 months after primersealing with 7 mm aggregate, the road will be sealed with a double/double seal. At this time the primerseal will have a uniform bleeding surface texture and ball penetration test value of 2. Use the information in RMS 395K. Design this seal, giving the cold residual binder application rate and the aggregate spread rate for both first and second layer of the seal.