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Published byLizbeth McKenzie Modified over 9 years ago
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ROAD PAVEMENT FORUM RECENT EXPERIENCES ON PPGS PROJECTS HISTORY 1993 RPF (BMLC) PPGS Task Group Formed 1994CAPSA Resolution to promote concept 1996Initial SANRAL Pilot Project 1999CAPSA Papers on PPGS issues and initial projects
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RECENT EXPERIENCE WITH PPGS DISADVANTAGES (CONSTRAINTS) IDENTIFIED AT CAPSA 1999: Acceptance of change in roles of employer and contractor Selection of appropriate guarantee sums Lack of contractor quality assurance systems Lack of contractor design skills Shortcomings in establishment of appropriate and attainable performance acceptance criteria Shortcomings in methods for specifying and measuring performance Selection of realistic performance guarantee periods
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RECENT EXPERIENCE WITH PPGS N3/1 PROJECT Length: 8,8 km of 3 to 4 lane freeway Pavement History:40mm AS (1985) 40mm AS 120mm BC 150mm C3(1974) 150mm C4 G7 Traffic: AADT – 105 000 ADTT – 5 000 Accumulative traffic (1974 – 2000): 25 x 10 6 E80/direction Remaining Structural life: > 15 years Functional distress:- rutting - surface cracking - riding quality
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N3/1 PPGS DELIVERABLES OF PROJECT To minimise noise generated by vehicles To limit ingress of surface water into the pavement To remove all rutting ≥ 6mm To improve and/or strengthen the pavement where visible distress is evident To improve riding quality and skid resistance To provide a medium to long term maintenance free and serviceable surface
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N3/1 PPGS CONTRACTORS OBLIGATIONS Contractor to submit the following with his tender: Design constraints for PPGS related products Quality Assurance Plan Use of “professional partner” Technical report (Pre-treat/repair method, product selection etc)
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N3/1 PPGS FUNCTIONAL PERFORMANCE PROPERTIES Visually Assessed Parameters (TMH 9) Instrumentally Assessed Parameters Deformation (shoving) Roughness (Riding quality) Surface failures Surface Friction (skid resistance) Surface cracking Rut depth Surface ravelling Surface macro-texture Bleeding
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N3/1 PPGS Acceptance Criteria for roughness Time (years) after issue of completion certificate Limit Value (Ave. 100m IRI) Max (%) of 1 km segment with IRI more than limit value 21,620% 1,95% 2,30% 41,920% 2,15% 2,60% 62,120% 2,45% 3,10%
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N3/1 PPGS Guarantees PPGS Defects Liability Period : 6 years (after issue of completion certificate Lane rental (after 4 years) :R 500.00 / hr / lane km Performance assessment periods :2, 4 and 6 years Product performance guarantee: R4 500 000.00 R 1 500 000.00 release of year 2 R 1 500 000.00 release of year 4 R 1 500 000.00 release of year 6
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N3/1 PPGS Item DescriptionUnitQTYRate Amount MATTERS CONCERNING WORK RELATED TO THE PRODUCT PERFORMANCE GUARANTEE SYSTEM (PPGS) The provision of a guarantee in terms of the requirements of the Product Performance Guarantee System Additional expenses and supervision costs for undertaking all work related to the Product Performance Guarantee of the surfacing Assessment and remedial work in respect of the Contractors obligation relating to the Product Performance Guarantee of the surfacing over the Guarantee Period Pre-treatment and surfacing in terms of the Product Performance Guarantee System L/Sum L/Sum L/Sum m 2 1.0 1.0 1.0 260000.00 C10.01 C10.02 C10.03 C10.04
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N3/1 PPGS TENDERS RECEIVED PPGS NON PPGS ALTERNATIVE Estimate R25, 084 m Contractor A (Alt)R24, 374 m R24, 202 m Contractor BR24, 887 m Contractor AR25, 114 m Contractor CR25, 852 m R22, 882 m Contractor A (Alt) Accepted
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N3/1 PPGS COMPARATIVE COSTS CONSTRUCTION SUPERVISION Lowest tender PPGS - R24,374 m Premium for PPGS - R 1,492 m Lowest conventional tender- R22,882 m Savings in supervision costs =± R0,90 m (3-4% of contract value) Supervision costs on PPGS project= 5% Supervision costs are recently completed conventional project of similar nature and scale = 8,7% Overall premium = ± R600 000,00
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N3/1 PPGS CONCLUSION CAPSA 1994 resolution: “PPGS is necessary for the development of cost-effective transportation infrastructure in South Africa. PPGS should be developed and implemented incrementally with due recognition of the principles of RDP and the need for education in the concepts of PPGS (paradigm shift). This will be necessary in order to prevent PPGS from developing into a barrier for the entrance of smaller entrepreneurs into the market.” Are we achieving this?
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