Senqu Bridge: structural work in demanding mountain terrain

The completed bridge extends approximately 825 metres across 16 spans, with a 100-metre central span and piers ranging from about 15 to 90 metres high. Its prestressed concrete deck includes an extradosed central section, combining aspects of a box-girder bridge with external cable support.

Constructed at roughly 1,400 metres above sea level, the long continuous structure had to respond to an irregular valley, exposed winds and the changing weather of the Lesotho Highlands. Every stage depended on carefully planned access, temporary works, lifting and coordination.

Greenhouse Construction contributed heavy structural steel work, specialist rigging, rope-access activities and on-site supervision within the wider bridge programme. The package drew on capabilities developed across structural steel, industrial infrastructure and complex site installation.

Teams worked around tall piers, steep slopes, elevated platforms and restricted lifting areas. Greenhouse Construction’s supervision helped coordinate its structural, rigging and access activities with the broader programme led by the WRES Joint Venture and principal contractor Webuild.

The tallest piers rise approximately 90 metres above their foundations—comparable to a building of more than 25 storeys. At these elevations, teams needed controlled access, secure working methods and clear communication between people operating at different levels.

Rigging plans had to account for each load, the available equipment, limited working areas and final positioning. Rope access offered a specialist means of reaching areas where conventional scaffolding or mobile equipment was not always practical.

The prestressed concrete box-girder deck was built using incremental launching. Deck sections of approximately 25 metres were cast in controlled areas and progressively moved forward across the completed piers until the structure spanned the valley.

Published project information records approximately 90 elevated access platforms covering around 1,200 square metres at heights from 16 to 88 metres. Greenhouse Construction’s structural work and rigging capability formed part of this tightly sequenced environment of steel systems, temporary works and specialist teams.

High altitude, steep terrain, strong winds, low winter temperatures and rapidly changing weather influenced crane operations, transport and work at height. The project required disciplined supervision, practical communication and the ability to adapt safely as site conditions changed.

The bridge was officially inaugurated in April 2026. For Greenhouse Construction, participation demonstrates the ability to deploy experienced specialist teams beyond the workshop and support complex, cross-border infrastructure through heavy structural expertise, rigging, rope access and confident on-site execution.