Infinite Consulting Engineers served as the prestressed, precast concrete consultant for the construction of two new road-over-rail bridges as part of the upgrade and dualling of the Route 69 from the N4 highway to Tsamaya Road in Mamelodi.
This leading structural engineering firm worked alongside 80 Rhodesville, the bridge consultant. M3 Construction was subcontracted to UMSO Construction and KPMM Joint Venture, the principal contractor, to construct the bridge. Calliper Consulting Engineers served as the road consultant.
By doing away with the need for level crossings, the new bridges have significantly improved rail and road efficiency and safety.
Bridge B5495B is owned and operated by Transnet Freight Rail. It is an 18m-long single span road-over-rail bridge with a superstructure that consists of 13 prestressed, precast-concrete M3 beams. The bridge foundations rest on piles of about 9m in depth.
Bridge B5590 is owned by Transnet Freight Rail (TrFR) and the Passenger Rail Agency of South Africa (PRASA). It was originally designed as a three-span bridge but was later modified to incorporate an additional railway line. To achieve clearance, one of the piers had to be removed. The main span is 23m in length and jack span, consisting of M7 prestressed, precast concrete beams, is 7,4m long. Foundations of the bridge rest on piles of about 10m in depth.
Coreslab manufactured and installed the prestressed, precast concrete beams.
The project was not without its fair share of challenges. Many of these were related to logistics considering that the railway line had to remain operational throughout the construction works. Therefore, use had to be made of construction equipment that did not interfere with the overhead-traction equipment. This was not always practical.
Moreover, crossing the railway line with construction equipment was not permitted. Therefore, equipment and machinery had to be rerouted onto the existing bridge when moving from one abutment to the other.
The prestressed, precast-concrete bridge beams also had to be installed over the weekend to avoid disrupting rail services.
Kobus Kotze, Managing Director of Infinite Consulting Engineers, attributes another successful outcome to excellent team dynamics between the engineering teams, contractors and clients.
