As a result of 30 years’ experience in refurbishment design, rehabilitation and maintenance of bridges and highway infrastructure, Egis was engaged by the King Fahd Causeway Authority (KFCA) to conduct a thorough condition and life assessment of the causeway linking the Kingdom of Saudi Arabia to the Kingdom of Bahrain. Egis was tasked with developing a maintenance strategy to extend the operational lifespan to ensure the crossing would remain safe, resilient, reliable and functional for many years to come.
The King Fahd Causeway is a strategic infrastructure asset crossing the Arabian Gulf and linking Saudi Arabia and Bahrain. With over 60,000 daily travellers, the causeway is the third busiest land border crossing in the world. Furthermore, it is an essential alternative to air travel and also serves as a symbolic link between the two nations.
Built between 1981 and 1986, the causeway was designed with an anticipated lifespan of 75 years. As a result of reaching the halfway point in its planned operational duration, the King Fahd Causeway Authority (KFCA) requested a thorough assessment of the infrastructure’s current condition, as well as recommendations to extend its lifespan. This work was required to be conducted with minimal disruption to traffic.
The King Fahd Causeway measures 25km in length and comprises a series of five bridges and seven embankments. The structure carries four traffic lanes and an emergency lane. The artificial Middle Island corresponds to the border between Saudi Arabia and Bahrain.
Implemented between December 2023 and February 2025, the condition assessment was characterised by the integration of innovative digital technologies with the aim of enhancing economic performance, reducing environmental impact and improving safety.
The latest drone technology was used to capture high-resolution photos and videos of the structures. The resulting data was transformed into 3D photogrammetry models of the bridges and embankments, and these analysed by engineers to identify defects and to categorise their severity. The use of drones increased the speed of inspection and reduced the numbers of inspectors and equipment needed on site, which greatly reduced the number of lane closures and disruption to the travelling public.
On-site inspectors checked the interior of box girders as well as other elements and areas that may have been flagged for closer inspection, such as bearings and expansion joints. Remotely operated vehicles were deployed for underwater inspection, along with divers, at selected piers.
The post-tensioning in the bridges, piers and flyovers was investigated and assessed using ground-penetrating radar and ultrasonic pulse echo scanning. At selected locations inspection windows were made in the concrete to expose the tendon strands to verify their condition and check the quality of the grout. The residual force in the strands was also measured and compared with theoretical results.
To assess the condition of the concrete, tests were carried out at selected locations of each of the bridges, flyovers and piers. These were crucial for evaluating the concrete’s durability and reinforcement integrity.
To ensure a comprehensive evaluation of all conditions, attention was paid to coated and uncoated concrete at bridge decks at different heights above sea level, as well as at the tidal, splash and dry zones of the piers. Cores were taken for concrete ageing analysis so that the current state of the concrete, particularly in the context of carbonation and chloride ion penetration, could be determined, as well as long-term viability.
A centralised GIS platform was created that combined several digital asset platforms, and which includes a digital twin with an interactive dashboard, artificial intelligence, field-critical data from inspections, drone-based photogrammetry, non-destructive testing results and, lastly, historical inspection records. Defects were colour-coded by degree of severity and recorded with GPS coordinates so they could be accurately placed on the 3D model. The GIS platform displays photos and relevant data when a defect is selected, an approach that allows for efficient review of defects and for planning of repair strategies. It also provides up-to-date, comprehensive monitoring of the causeway’s structural health.
Artificial intelligence was used to analyse the photogrammetry and develop tools for automatic defect detection, streamlining future inspections and tracking changes.
As regards project challenges, it should be noted that the causeway is exposed to a harsh marine environment characterised by high humidity and salinity, both of which can compromise the durability of its concrete structures. These climatic challenges also impacted project execution. During the summer months, work on site was not allowed between noon and 3pm to mitigate health and safety risks associated with the extreme heat and humidity. We also had days when wind speeds were too high for the drones to fly, and which also exceeded the safety threshold for the bridge inspection vehicles.
The sheer size of the project – 12.5km of bridges – provided its own set of challenges and required careful preparation of the inspection and testing locations to optimise the use of equipment and associated lane closures.
As regards outcomes, the first thing to emerge from the investigations was the good overall condition of the structures in terms of their age and the associated environmental conditions. The defects found were typical and only require routine maintenance.
NDT and concrete ageing analysis showed that the structures have a predicted service life well beyond the original 75-year design life. This is due to the durability measures that were taken at the construction period, including high – and well executed – concrete cover values of 75mm for the piers and 50mm for the decks. These were in accordance with the design code and were well maintained by the contractor, as per design drawings.
The type of concrete used for the causeway is also highly relevant. It has low porosity and permeability values, which limits the entry and the spread of aggressive agents. Furthermore, the physical and chemical concrete durability indicators – including resistivity and chloride diffusion coefficient – were found to be characteristic of a high-durability concrete. The multilayer coating applied in the most exposed areas of the tidal and splash zone – from -2m below sea level to 8m above sea level at the precast piers – proved efficient in preventing carbonation and chlorides penetration. Another relevant factor was the prestressing in all parts of the structures, which reduces cracking and thereby limits the entry of aggressive agents.
Based on these results, Egis developed a detailed inspection and maintenance plan to carry out the necessary repairs in the short, medium and long-term. We also provided recommendations to extend the life of the structure, ensuring the longevity and safety of the asset. Inspections are optimised by carrying out major inspections on a five-year cycle and adopting latest practices to inspect the condition of key components.
As the results confirmed the effectiveness of the protective coating applied to the bridge piers, it was recommended that this protective coating be extended to parts of tall piers that are currently not coated. Similarly, hydrophobic impregnation was recommended for the box girders as a barrier to hinder carbonation and chlorides penetration. This type of protection is favoured for the box girders because it would not mask detection of any new cracks, important for monitoring the condition of the spans over time.
The installation of a structural health monitoring system that would track the movements of the different parts of the bridges was also recommended, with sensors installed at critical areas, as well as regular monitoring of chlorides ingress and carbonation. The latter would confirm an effective schedule for implementing further protective measures as well as for verifying the long-term effectiveness of existing measures and their future renewal schedule.
By prioritising the maintenance and preservation of existing structure above new construction, the project aligns with today’s focus on sustainability by ensuring long-term durability and minimising environmental impact. And, while inspection and maintenance of large infrastructure often causes disruption to the users, this can be minimised by harnessing cutting-edge technologies to deliver precise and efficient results and by solving problems intelligently.
As Egis’ country managing director in Bahrain, Kuwait, Jordan and the Eastern Province of Saudi Arabia says, “The bridge is in remarkably good condition for its age given the traffic and humidity conditions. With our monitoring and maintenance plan we’re confident it will continue to bridge Saudi Arabia and Bahrain for many more years to come”
** As issued in Bridge Design & Engineering
