Six bridges flagged for emergency work after Joburg rains
The Johannesburg Roads Agency (JRA) has embarked on the rehabilitation‚ reconstruction and repairs of six bridges across the city‚ following heavy rainfall and flash flooding in early January 2017.
City of Johannesburg Transport MMC Nonhlanhla Makhuba said: “In the past few years Johannesburg has experienced a number of severe weather conditions resulting in heavy rains and flooding of low-lying areas. This flooding has not only had a devastating impact on low-income communities where lives and possessions have been lost‚ but we have also seen devastation to our road infrastructure‚ vehicles and even road users. We understand that a well maintained road infrastructure is essential for economic growth and consequently as part of the city’s risk mitigation strategies‚ six listed bridges have been prioritized to ensure public safety‚ safe and reliable access for the community and protection of biodiversity.”
JRA Managing Director‚ Dr Sean Phillips‚ said the bridge upgrades were motivated by flood impact assessments carried after heavy rainfall on 6-7 January‚ which assessed the extent of damage and impact or associated risk to life‚ limb and property.
“Site visits indicated the need for emergency rehabilitation‚ reconstruction and repairs of six bridges.
“The extent of damage is estimated at R113‚5 million.”
The affected bridges are Belgrave‚ Joe Nhlanhla‚ Cork Avenue‚ Bridge Road‚ Spring Road and 432 Modderfontein Road.
“We are fast-tracking these six bridge repair projects and construction has been scheduled for July 2017‚ with the exception of Cork Avenue Bridge where construction is already under way‚” Phillips said.
He added: “Motorists and pedestrians are advised to use alternative routes with the closing of the Joe Nhlanhla and Bridge Road bridges over the Jukskei River.”
JRA provided more details in a statement‚ outlining the work required on each bridge:
Modderfontein Road is the main connector road to Lyndhurst. JRA said the Modderfontein Road Bridge over the Jukskei River sustained extensive damage during heavy rainfall‚ rending the bridge unsafe for long-term use. Planning is under way to have the bridge rehabilitated at an estimated cost of R10 million in the 2017/2018 financial year. The bridge remains open to the public until the rehabilitation commences.
The damage sustained is owing to the abnormal amount of stormwater that flowed through the bridge‚ which has also left services mounted on the bridge exposed. In addition‚ riverbank erosion was caused by high and fast moving water that exceeded the level of the banks. The eastern and the western waterways under the bridge and the backfilling of the wingwalls have also eroded. Guardrails were destroyed and the gabions baskets which normally protect the bridge from erosion were washed away. The rehabilitation will include building of gabion walls on the river banks‚ reshaping and re-vegetation to prevent soil erosion‚ construction of retaining walls‚ replacement of roads signs swept away by stormwater‚ and desiltation.
The Spring Road Bridge will be demolished and reconstructed at an estimated cost of R15 million. Emergency repairs will be undertaken to prevent failure of the road crossing. The main sewer line and other important services remain exposed due to excessive erosion. Therefore‚ immediate stabilisation is required to ensure sewage is not discharged into the stream. New gabion walls will be built on the river banks together with reshaping and re-vegetation to prevent soil erosion. Road signs swept away by storm water will also be replaced.
Joe Nhlanhla Street is the main connector street for East Bank‚ Setswetla residential areas and the Alexandra Township. Joe Nhlanhla Bridge is located on Joe Nhlanhla street over Jukskei River and
was severely damaged during the heavy rainfall‚ leaving the bridge unsafe for motorists and pedestrians. The estimated cost to rehabilitate the bridge is R10 million. Emergency measures include extending the bridge structure in order to increase the volume of water that can flow through the bridge.
Bridge scour is evident‚ as a result of the removal of sand and rocks from around bridge abutments or piers by swiftly moving water. The scouring has compromised the integrity of the structure and therefore the apron slabs which lie above the ground will be replaced. Excavating‚ reshaping and re-vegetation together with the replacement of gabion boxes will reinforce the banks and prevent soil erosion. The damaged sewer line will be repaired along with repairs and resurfacing to the existing road surface on the bridge abutments and bridge neck. Waste removal will be carried out along with the replacement of road signs washed away by stormwater.
Cork Avenue Bridge over the Klein Jukskei River is completely destroyed and will be demolished and reconstructed at an estimated cost of R15 million. The existing sewerline and other services are severely exposed due to excessive erosion caused by the failure of the stream crossing. The bridge will require gabion walls on the river bank‚ along with the reshaping and re-vegetation to prevent soil erosion. Retaining walls will be reconstructed‚ de-siltation upstream and downstream will be undertaken and road signs swept away by the stormwater will be replaced.
Bridge Road Bridge is located on Bridge Road over the Jukskei River; the flooding has caused extensive damage to the infrastructure which is a threat to the linked sewerline. The eastern and western waterways under Bridge Road over the Jukskei River have been swept away and the middle supporting bridge pillar is completely eroded with its foundation exposed. Remedial intervention is underway and the bridge is scheduled to be demolished and remains closed. The public have been redirected to alternative routes until the bridge is reconstructed. This will include new gabion walls‚ reshaping and re-vegetation of the bank walls to prevent soil erosion‚ construction of retaining walls‚ replacement of road signs swept away by stormwater and desiltation. The estimated cost for the reconstruction of the bridge is R60 million.
JRA has approved the installation of Belgrave Bridge boom gates to safeguard road users during flood conditions. Belgrave Bridge in Bryanston is a low-lying bridge that frequently floods during heavy rain. Torrential downpours in January resulted in increased water flow‚ erosion of the river banks‚ sedimentation‚ turbidity and risk to motorists and pedestrians.
The estimated cost of the rehabilitation of Belgrave Bridge is R3.5 million. The installation of the boom gates is pending the approval of a Traffic Management Agreement and a formal commitment from the community to manage the boom gate during flood conditions. Failure to comply with the agreement conditions will result in the removal of the booms.
In prioritising the community’s safety‚ JRA said it has serviced Belgrave Bridge’s stormwater drains and installed solar powered flood lights‚ bollards‚ road studs‚ and gabion baskets on one side of the river to address soil erosion. The river will also undergo further desiltation with additional gambion baskets installed.
The JRA is a City-owned agency responsible for the maintenance‚ repair and development of Johannesburg’s road network and stormwater infrastructure‚ including bridges and culverts‚ traffic lights and signage.