1  Understand limits of surfacing seal TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing  Understand seal classification

2 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing

3 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing

4 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing Influencing factors:  Traffic volumes  Traffic loading  Traffic actions  Gradient  Surface texture required  Maintenance capabilities  Construction techniques, skills, plant  Environmental conditions (Noise, UV etc  Quality of base (new seal)  Conditions/uniformity of existing surface (reseal)  Texture of existing surface (reseal)  Initial and life cycle costs

5 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing Traffic : Equivalent light vehicles (elv) / lane / day  ELV = L + 40 H (1 heavy = 40 elv) Construction techniques: Double seals (S2) are less sensitive and thus more forgiving than single seals (S1)  S1 requires good shoulder to shoulder contact  Lower aggregate layer is keyed in S2  Upper aggregate can be retained by fog spray S2  Increased voids in S2  Corrections to 2 nd and/or 3 rd spray applications possible in S2

6 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing

7 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing

8 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing

9 TRH 3 : Surface Seals for Rural and Urban Roads Selection of Appropriate Surfacing