Karuma Bridge repairs 80% complete - engineers

At least 80 percent of the repair works on Karuma Bridge have been completed, engineers working on the facility have revealed.

The engineers said they are optimistic that full traffic flow on the bridge will resume by January next year, adding that by late December this year, traffic for light vehicles will commence.

Mr Charles Bongomin, the deputy resident site engineer, said most of the critical works on the bridge, including concrete panning and bearing replacement, have been done.

“We removed the entire concrete which was there because it was too weak by then. We removed the deck, we provided new formwork, and we provided new concrete itself. We are just waiting for the curing stage so we can reopen,” Mr Bongomin told Daily Monitor at the weekend.

He added: “The ongoing work is about 79 to 80 percent by now. The remaining work is the auxiliary, to those simple works which are remaining. The retaining wall, the approach slab, and maybe some elements of asphalt overlay. The works are simple, cannot delay or cannot affect the operation of the road.”

The site engineers reported that the bearings were also replaced.

New features to curb accidents 

Mr Bongomin explained that new features will be introduced within and along the bridge to curb accidents, including vehicles plunging into the River Nile due to the design of the bridge and overspeeding.

“We also encountered several challenges. Normally here on the curve, vehicles enter into the water. So we provided that super elevation because we have introduced a lighting system within the bridge section, including even the approach,” he said.

He added: “So we shall have lights, and we shall put road safety measures in terms of rumbles and adequate road signs so that you scale down your speed as you approach the bridge. We will also put cats-eyes, those shining things in the middle of the bridge. So these are some of the design considerations that we have done.

The bridge is in an S-curve, meaning in the geometry design, you marry this structural element of the bridge, especially the deck, with the geometry of the road to ensure the weight of the vehicle is perpendicular to the bridge.”

Mr Bongomin noted that several lives have been lost to drowning as people attempt to cross the Nile while the bridge remains closed.

“Right now we have challenges because of this diversion of the road. We have lost lives, there are some sections where people are crossing, in our neighbourhood here, we lost people last week, they recovered one body but others, they were looking around,” he said.

He added: “So we need to see that we put all measures in place so that we reopen, which I am happy we are almost there.”

Mr Bongomin said the old bridge is strong enough to remain functional, even if there are delays with the construction of a new one. 

“There is no cause for concern at the moment,” he said.

Mr Lawrence Pario, the head of bridges and structures at Uganda National Roads Authority (Unra), said structural defects on the Karuma Bridge were detected in May, leading to the authority to allow only light traffic to use the facility.

Mr Pario said a contractor was hired in July, and subsequent assessments identified two major defects that required urgent repairs

“Defect number one was the concrete. For a standard bridge, the concrete should be grade 40 or higher, but tests revealed the concrete here had deteriorated to grade 14. This was due to overloading and continuous fatigue, which weakened the material over time, causing fractures and reducing its strength. To address this, we recommended replacing the concrete, which has now been done,” he said.

He added: “The second issue was the bearings. Every bridge with bearings requires them to be replaced every 20 years at most. However, this bridge had gone for 60 years without such maintenance. As a result, all the bearings had collapsed. To address this, we replaced them with new ones, which have now been installed.”

Mr Pario, however, said most of the work on the bridge has been completed, with only auxiliary tasks remaining, which are expected to be finished within two to three weeks.

“We have one more component, expansion joints. you know bridges expand and contract. But the expansion joints are still on the sea [transit], so they are going to be around here by mid-January 2025,” he said.

The head of bridges and structures at Unra dismissed social media rumors claiming that the bridge required certain rituals to be performed, including human sacrifice.

“I want to emphasise that the construction of a bridge is physical science, it is not ritual, it is not witchcraft. We have been hearing that before this bridge is reopened, we need around 400 human heads. Bridge engineering is about physical science, you don’t need the head of a chicken, cow, or goat, you don’t need anything. You just need to understand material science and physical science engineering and that is it,’’ he said.