PRESENTATION ON FLOATING ROADS BY MARTIN HMENSA DEPARTMENT OF FEEDER ROADS, GHANA

OBJECTIVE To share the successful results of constructing roads on peat with sand and gravel in Ghana.

BACKGROUND Request for access road to a fishing community at the coast Community cut off by two rivers, a stream and a lagoon/estuary Community near the confluence of two rivers Request made for three bridges Length of stretch to be traversed was 450m.

STUDIES CARRIED OUT Profile of the depth of peat on stretch Specific gravity of peat Plasticity tests on gravel for fill Quality of sand for fill Salt and other chemical content of water Highest level of water in lagoon Effects of tides on highest water levels type of vegetation and its effect.

SOME RESULTS OF THE TESTS/STUDIES Peat deeper than 4m all sections (Manual Auger Equipment used with little effort) Profile obtained at the other project site Range of S.G of peat: 1.89 to 2.05 Salt content: variable; ranges between 27.2% and 33.1% Highest level of water estimated at 1.5m above ground.

TEST RESULTS ON PEAT QUANTAB READING% NaCl S.G *30.88*1.96*

SOME RESULTS OF THE TEST ON THE GRAVEL FILL Liquid Limit (LL):Range:27 to 33 Average:30 Plastic limit (PL):Range:16 to 18 Average:17 Plasticity Index (PI):Range:12 to 15 Average:13 Maximum Dry Density : Range : 2020 to 2100 Kg/M 3 Optimum Moisture content (OMC): 7.9 to 10.7 Average:10.0

CBR OF GRAVEL AT DIFFERENT COMPACTION EFFORTS 100% Proctor –Range: 63 to 96 (Average : 72) 98% Proctor –Range : 42 to 64 (Average : 53) 95% Proctor –Range : 19 to 27 (Average : 24) 93% Proctor –Range : 14 to 20 (Average : 18)

DECISIONS TAKEN AND IMPLEMENTED Bridges and viaducts not viable A series of mass concrete pipe culverts selected Peat in channels at river culvert positions displaced with sand Gravel used to fill other sections Additional culverts to be constructed when necessary. Base of fill was broadened - 11m Only the upper layers were compacted.

DCP TEST RESULTS OF FILL MATERIAL DATE OF TEST: ASEMASA – ANLO BEACH EQUIPMENT : DCP WR24900 AO1 LOCATIONTHICKNESS(mm)DEPTH(mm)INSITU CBR LHS 1.8M FROM C/C RHS 2.0M FROM C/C C/C RHS 2.4M FROM C/C

DCP TEST RESULTS OF FILL MATERIAL DATE OF TEST: ASEMASA – ANLO BEACH EQUIPMENT : DCP WR24900 AO1 LOCATIONTHICKNESS(mm)DEPTH(mm)INSITU CBR LHS 2.0M FROM C/C C/C

PROBLEMS ENCOUNTERED Objection of communities to relocation of road and loss of two bridges Observation of taboo days (Tuesdays) Demand for performance of rituals Equipment got stuck at sand pits Equipment got stuck in peat Slow rate of work

RECOMMENDATION AND CONCLUSION The floating has performed satisfactorily over a period of 8 years. Monitoring would be continued. It is a cost effective option of providing access. Perhaps this has been successful because ADT is about 50vpd. Take the risk to float a road under similar circumstances to reduce cost and to provide access to deprived and isolated communities.