The Newclare underpass development is a resounding success, and an outstanding civil engineering feat. Lauded by the South African Institution of Civil Engineering, the underpass is a welcome safety feature in the area.
The Johannesburg Development Agency (JDA) has built a bridge across a dangerous railway in the Newclare and Westbury communities.
The Newclare railroad underpass, which took 18 months to complete, now links the two suburbs. It is a component of the Corridors of Freedom, in line with the City’s Growth and Development Strategy 2040 (GDS), which will ensure Joburgers live nearer to their places of work and are able to work, live and play in them without having to use private motorised transport.
The construction did not disturb rail services.
Roger Barker, chief engineer at Murray & Roberts, said: “The underpass is part of the Bus Rapid Transit system so that they could develop additional passage ways from one side of the railway embankment to another and it was done with two separate structures that were constructed and jacked to the centre of the railway line.”
Jacqueline Bird, civil engineer at Murray & Roberts, said: “It was a bit of an engineering feat and included some lateral support work, normal concrete work, bridge jacking and road works.”
According to a statement from Murray & Roberts, the project involved constructing two reinforced concrete structures, one on either side of the railway embankment. The two structures were jacked through the embankment until they overlapped on the centre line of the railway to form the underpass structure. The 52.5 m underpass is 12 m wide, allowing for two 3.7 m road lanes and two 2.3 m pavements. The structures measure 28 m by 24.5 m.
CHALLENGES AND BENEFITS
Barker said the project presented several taxing technical challenges that required cooperation between parties.
“For example, the construction team had expected to encounter mine sand from historic mining operations in the area in the embankment material. In reality, the embankment material was found to be well-compacted fill with high clay content and a greater volume than expected of very hard quartzite bedrock, which required drilling and blasting.”
The bridge construction employed 30 local labourers who received training in basic construction. Rea Vaya approached small to medium enterprises to manage the traffic on the roads around the site, build speed humps to improve road safety in the area, and improve pavements.
SAFETY MEASURES
Railway flagmen and scaffolding erectors received safety training to avoid accidents in the densely populated area.
Bird said: “Due care and attention had to be paid to construction noise levels. Compressors were specially silenced and noise and vibration from blasting was managed by using small-charge-delayed blasting.
“The material excavated from the underpass was placed to reinforce the toe of the adjacent railway embankment, eliminating the need to haul this material across congested roads in the vicinity of the project. This was seen as a safety consideration, since members of the local community use the streets for recreation activities.”
EXCELLENCE RECOGNISED
In October 2013, the JDA featured in the South African Institution of Civil Engineering (SAICE) Awards for the Most Outstanding Civil Engineering Achievements for 2012/2013.
The agency received a commendation for Technical Excellence Projects in the National Projects category for the Newclare and Bosmont underpass, between Price and Hoy streets.
The SAICE released a statement at the time saying: “The civil engineering industry makes a huge contribution towards infrastructure creation and the resultant economic and social development in South Africa.
“The City of Johannesburg’s urban development policy focuses on the need to create compact cities and limit urban sprawl to use urban infrastructure effectively. The primary measure to support this policy is the Rea Vaya Bus Rapid Transit system. The road-under-rail crossing linking Price and Hoy streets, which run parallel to the railway at the Newclare Railway Station, assists with traffic flows in this area.”