Heritage Cases

The proposed upgrade of D1867 project comprises of the construction of earthworks, layer works, ancillary works and surfacing from gravel to blacktop, storm water drainage, and major drainage structures as well as the construction of Mozana Bridge. The existing Road D1867 is approximately 7.5m wide and 10.9 km long with a road reserve of 30m and the project entails the upgrading and widening from 7.5m to 8.5m wide surfaced Type 4 Low Standard Secondary Road with a carriageway width consisting of 2 x 3.5m lanes and a 1.5m concrete paved footway. The design speed on the road is 60km/h. The proposed upgrade will start from KM 6+000 of the existing Road D1867 at approximately GPS coordinates: 27°16’51.34”S and 31°14’20.94”E to KM 16+900 of the existing Road D1867 at approximately GPS coordinates: 27°20’38.26” and 31°11’3.99”E. A portion of the road from km 6+600 to km 8+00 falls within Mpumalanga Province and the rest under KwaZulu Natal Province. The existing bridge structure has deteriorated to the degree that significant maintenance is required to keep the bridge in service. The replacement of the existing bridge is necessary due to the following: • The existing one lane bridge is functionally deficient as it`s widths do not satisfy the current KZN DOT standards in terms of horizontal curve and road gradient considering the amount of traffic that utilises the bridge. • The width of the existing bridge cannot accommodate the road carriageway and the foot walkway. • With the upgrade of the road to blacktop, the existing bridge has a potential to become a black spot due to increase traffic volume. The recommended preferred build alternative consists of replacing the existing one-lane bridge with a two-lane bridge constructed south east of the existing bridge at about Km 7.2 at GPS coordinates: 27°17’ 14.1” S, 31°13’ 47.5” E. The proposed Mozana bridge deck will be 56m long continuous slab with 4 spans of 14m length. The bridge deck will be 11.12m to accommodates 2 x 3.5m wide lanes with shoulders of 0.75m wide on both side of the bridge and a 1.5m foot sidewalk on the south edge of the bridge. The total physical footprint of the bridge is approximately a 622,72m2 and more than 10 cubic metres of soil, and other material will be excavated, removed, or moved during construction of the bridge. The bridge is designed for a 1:10 return flood to pass under the deck soffit. The abutments and three piers are founded directly on the rock within the riverbed and anchored with dowels. The GPS coordinates of the abutments and two piers are provided below from the direction of the start point of the road: Structure Latitude Longitude Abutment (E) 27° 17’ 13.12” S 31° 13’ 49.44” E Pier (D) 27° 17’ 13.35” S 31° 13’ 48.98” E Pier (C) 27° 17’ 13.58” S 31° 13’ 48.54” E Pier (B) 27° 17’ 13.83” S 31° 13’ 48.11” E Abutment (A) 27° 17’ 14.09” S 31° 13’ 47.70” E A 250mm thick approach slabs will be constructed under the roadway of the bridge. The approach slabs will be supported on the abutments at one end and rest on the fill towards the other end. The following are the specifications of the approach slab to be utilised in the construction of the bridge: • The slab will extend 4.5m from the curtain wall of the road centreline, with a fall of 100mm. • The slab will be kept 100mm clear of the wingwall faces to prevent fouling of the wall, should settlement take place. • The top of supporting rib will be 800mm below the finished road at the carriageway centreline. • The approach slab will be designed for both earth load and NA loading over a span of 2m in longitudinal direction of the structure. • Waterproof underlay or 40mm thick blinding will be provided under the approach. Reinforced concrete solid type piers that are 0.6m thick founded on spread foundations are proposed for the bridge. The bridge deck is a four-span continuous cast in situ reinforced concrete slab. The bridge deck is continuous of over the pier and bridge expansion joints are provided at the abutments. The bridge parapet will be of F type shaped reinforced concrete parapet and designed in accordance with TMH7: Part 2 clause 3.51.2 – Type 1 balustrades: 100kN impact force. The proposed bridge will be constructed while traffic is maintained on the existing bridge for use as a bypass during the construction of the new route. The existing bridge will not be removed following construction of the new bridge. construction of a new road of approximately 8.5m wide and 860m in length which will start from KM 6+800 at approximately GPS coordinates: 27°17’ 11.00”S and 31°14’ 01.60”E to KM 7+660 at approximately GPS coordinates: 27°17’ 26.60”S and 31°13’ 51.06”E. At Km 15.520 the road crosses an unchanneled valley bottom wetland (Wetland Unit UCVB1) from approximately GPS coordinates: 27°19’ 38.15”S and 31°12’ 41.64”E to approximately GPS coordinates: 27°19’ 38.45”S and 31°12’ 41.29”E. This wetland area will require rockfill under the road for about 50m long and 15 m wide and 0.750m thick to allow the water to run freely under the road where a six (6) stormwater culverts of size 900PC will be installed so as to prevent the water to be cut off from the wetland. The existing structures and stormwater pipes at Km 15.520 will be removed and decommissioned.