Tridevco (Pty) Ltd., appointed VIP Consulting Engineers to investigate, plan, design, obtain sanction from the various authorities and supervise the construction of an underpass structure that would provide a link between the two areas, east and west of the R21, and comply with the requirements of the traffic study and Traffic Master Plan.
Riverfields Boulevard will pass under the National Road R21-2 which is ± 660m south of the existing R23 route overpass in the Ekurhuleni area.
The proposed construction method is to construct a temporary bypass on which the traffic will be diverted. The underpass structures for both carriageways will then be constructed, completed, where after the bypass will be demolished.
In order not to disturb the existing supporting earthworks, the abutments were found on cast in-situ augered piles. The pier columns were likewise found on piles. The soffits of the deck have been designed to a curved radius to provide a pleasing arch effect.
Prestressing the deck was not considered as the long term creep effect would require almost continuous maintenance to the end joints and in effect the roadway.
Traffic studies determined that, in order to link township development on both sides of the R21, a link be constructed consisting of two dual lane carriageways. The choice of underpass or overpass was extensively investigated, and with the blessings of the owner of the R21, SANRAL, it was decided that it would be an underpass after due consideration. This would be called the Riverfields Boulevard.
From the outset it was recognized that these bridges would go unnoticed to the traveller on the R21. For the motorist on the Riverfields Boulevard however, it should be an aesthetically pleasing enhancement to the area served by the road.
This effect was achieved by the introduction of shallow arched soffits supported on slender circular columns. The latter was used in combination of groups and the surface of each was enhanced with longitudinal flutes which provide pleasing and interesting shadow patterns.
The total cost of the project was ±R48,0 million.