The Lekki Ikoyi link Bridge is the first ever cable -stayed bridge in Nigeria.The bridge represents West Africa’s first cable stay bridge embedded in Lagos lagoon. The 1.36km bridge connects the Lekki area to the Ikoyi axis of Lagos. While helping to ease vehicular traffic around the area, the wide curbs of the bridge also serves as a recreational facility for residents of the area.
Designing the Lekki Ikoyi Link bridge
Lagos,a city home to millions and West Africa’s largest financial and economic metropolis. Almost no other city can boast of growth as rapid as Lagos. Yet, that growth puts enormous pressure on its infrastructure. The city is a logistical hub, not only for the entire country but also for regions beyond its borders. The city is synonymous with change, opportunities and challenges for some seventeen million inhabitants.
In accordance with urban development plan, this ever growing city is expanding towards the east. Julius Berger, one of the top construction companies in Nigeria was commissioned with the task of decongesting traffic around Eti-Osa, Lekki, Epe and Ikoyi environs by providing an additional bridge across five cowries creek..
An additional bridge across five cowries creek has to meet two requirements:
Alleviate commute for tens of thousands of people crossing the lagoon to the city’s business district.
The bridge should also satisfy the special aesthetic requirement of Lagos state. A structure destined to become a landmark, thus the Lekki -Ikoyi Link Bridge was born.
The construction project faced many challenges from the start, deciding on the route proved difficult at first. Only one of the many different options met the requirement. For the most part, the chosen route passes through unpopulated terrain and connects with the existing road network, it allows maritime traffic to pass while still meeting requirement of the depth slope not exceeding 3.5% to prevent a slowdown in the flow of traffic.
The nearly one and half km bridge is divided into two parts: an approach bridge and the main bridge, its most striking characteristics: the pylon.
Construction of the Lekki Ikoyi Link Bridge
The schedule for the completion of the iconic structure was very tight; work had to be performed effectively, precisely and swiftly. To fulfill these requirements, the approach bridge was built using a panel construction method.
The individual full span bridge panels were pre-fabricated on land and transported into the construction site on pontoons. The heavy bridge panels which can weigh up to 250 tons each and can only be transported at high tide due to the shallowness of the lagoon’s water. Julius Berger had to develop special launching gantry to install the 92 concrete slabs.
The main bridge was also constructed using individual pre-fabricated elements.
To reduce execution risks, Julius Berger decided to use long lines segment framework, this ensured that every element of the 75m super structure fits precisely with the other elements. Each and every segment is unique; having to remake just one individual segment will delay construction by four to six weeks.
An impressive 120 meter long launching gantry was used to install the segments. The pylon was also created at the same time while using the cantilever beam suspend the bridge.
As can be expected, the unusual shape of the pylon’s legs causes them to slant inwards; this is corrected by two temporary struts applying two hundred tons of pressure. The lower strut pushes the pylon’s legs apart by exactly 6 – 6 millimeters. A precision job involving tremendous forces.
The pylon’s futuristic design calls for innovative solution, hydraulic self climbing framework enables it to grow to a height of 90 meters.
A 110 meter free standing crane then transports the composite steel boxes for anchoring the top the incline stay cables. An insulation tolerance of +- 0.4 degree for the cables, this work has to be performed with upmost precision.
In the vicinity of the bridges incline staycables , the segments are installed beginning at the pylon and untwining both directions using segment lifting frames positioned on either end. An inclined stay cable is anchored and tightened at every four segments, only then can additional segments follow. Every change to the structure such as the installation of individual segements , movement of equipment or the tightening of incline stay cables influences the pylon sensitive structural integrity over the course of the construction project.
Settlement is expected and monitored on a continuous basis. Despite the structure’s light weight filigree appearance, enormous horizontal and vertical forces are in play.
The planning and construction of this technical masterpiece was completed within just 42 months with up to 800 Julius Berger employees working on the project at any given time
The Lekki-Ikoyi Link Bridge was built at a cost of N29Billion.
The bridge was commissioned by the then executive governor of Lagos State, Babatunde Raji Fashola. He commissioned the bridge on Democracy day (29th of May 2013) to commemorate his sixth year in office.
The Lekki-Ikoyi Link Bridge was officially opened to the public on June 1, 2013 with a tollgate located at its Lekki end. The toll gate is operated by the Lagos Tolling Company.
Class M: Motorcycles with 200cc capacity and above
Class I: Saloon cars
Tariff : N250
Class II: Mini-Vans, SUVs and light pick-up trucks
Class III: Non-commercial buses with maximum seating capacity of 26 persons
The following vehicles are not permitted on the Lekki Ikoyi Link bridge; they include but not limited to: public transport buses, heavy duty trucks and Lorries.