December 2013
CONSTRUCTION WORLD
72
Professional Services
C
The rehabilitation of the ARMCO pipe arch
culvert on the p14-1 at km 5,2
N
aidu Consulting was appointed by the KwaZulu-Natal Depart-
ment ofTransport (KZN-DOT) for the inspection and conditional
assessment reporting of numerous existing Armco culverts on
various provincial roads within District 22.
On completion of inspections typical generic problems were
identified in these structures of varying size and geometry.
The relatively large low profile arch Armco Culvert of 6 m span,
3,6 m rise and 32 m length with approximately 4 m of fill above was
found to have a significant level of deterioration. The invert was se-
verely corroded to a state in which it was no longer able to resist the
full lateral earth pressures and buckled in cross-section for the full
length of the culvert. The structure’s roof and invert had significantly
distorted indicating that action was immediately necessary. The ex-
tent of distortions were becoming noticeably amplified between
regular monthly inspections. Evidence of gradual failure occurring
in the Armco could be felt while travelling over the culvert due to
the notorious depression in the pavement caused by the continuing
settlement of the fill above the Armco Culvert.
The structure was flagged to the client as being potentially
hazardous for use by the public especially with the passing of heavy
agricultural, timber hauling and construction vehicles recorded dur-
ing site visits.
Designer and contractor had to work very closely incorporat-
ing design and construction methods to overcome the challenges
arising from this project. Close consultation with suppliers helped
optimise the construction process. Construction commenced early
March 2012 and extended over 3 months to completion as sched-
uled. The project was completed within its budget of R1,4-million.
A cost savings in excess of R4-million was realised by the client,
by opting to construct the culvert within the old culvert and use
the existing Armco as a permanent shutter. This eliminated the
need for a detour which would have needed to be constructed to a
Class 2 surfaced road standard. It is estimated that if the department’s
investigation did not occur at the time it did, complete catastrophic
structural failure of the original Armco culvert would have occurred
with the costs for culvert replacement close to triple that of the
budget spent.
The risk to the travelling public was immense and could have
resulted in fatalities and thus this more efficient yet challenging ap-
proach was well received. This project highlighted the co-operation
and joint planning between client, designer and contractor to ensure
the supply of a sound structural solution.
Project information
• Project name: The rehabilitation of the Armco Pipe
Culvert on the P14-1 and km 5,2
• Company entering: Naidu Consulting
• Project start date: 1 March 2012
• Project end date: 30 May 2012
• Client: KwaZulu-Natal Department of Transport
• Main contractor: W.K. Construction
• Principal agent: Naidu Consulting
• Project manager: Naidu Consulting
• Consulting engineer: Naidu Consulting
• Project value: R1,4-million
