Monitoring the Benjamin Sheares Bridge

Opened in 1981, the Benjamin Sheares Bridge is the longest bridge in Singapore, spanning 1.8 kilometers.  It is also the tallest at 20 meters. The bridge was named to honor Dr. Benjamin Henry Sheares, the second president of the Republic.  Built over reclaimed land, the bridge is made of pre-stressed concrete and links East Coast Parkway to Marina Bay on the west coast. 

The Marina Bay Bridge across Marina Bay was officially opened on April 24, 2010. There are two components to the bridge — a six-lane roadway for vehicles and a six-meter-wide curved pedestrian connection that overlooks Marina Bay. The spiral-shaped pedestrian bridge, called the Helix Bridge, is 280 meters long, while the Bayfront Bridge, spanning 303 meters, was picked for the parallel bridge for vehicles.

The Bayfront Bridge provides a direct connection between Marina Centre and Marina South. The opening of this new road network provided vehicular access to developments in the Marina Bay area, such as the Marina Bay Sands Integrated Resort Gardens by the Bay and the Marina Bay Financial Centre.

Monitoring Solution Providers Pte Ltd, (MSP), was involved in monitoring the movement of the Benjamin Sheares Bridge and later, the Bayfront Bridge.

To carry out the project, MSP was challenged with severe conditions.  The monitoring instruments needed to have high ratings in dust and water protection since the instruments were placed on the pile cap that sat on the water of the Singapore River.  Additionally, the power consumption of all equipment used had to be kept to a bare minimum due to the lack of a constant power supply.

This project was the first use of a high-accuracy monitoring station for bridge movement monitoring in such severe environmental conditions. To reach the instruments, workers had to hire a boat to reach the pile cap where the instruments are installed. It was important to make sure the instruments would not rust and stay durable.  

Another major challenge for the system was the fact that there was no constant power supply on the pile cap.  This was the first time for the monitoring system to constantly monitor a job site without continuous power.  An MSP engineer devised a solution to take the public lighting power that operates only from 7 p.m. to 7 a.m. The engineer visited the monitoring site every two weeks with a control box that included a PDA (personal digital assistant), battery charger, power converter, timer, and four car batteries with which the PDA can last for two weeks.

There, software linked the PDA and server together for downloading data and updating the software from the instruments.

Kenny Lim, managing director of MSP, said, “For the design of the instrument stand, we needed to consider the vibration created by the vehicles that travel on the bridge, the heat, the sunlight and the rain.  To reduce the vibration, they placed a five-millimeter rubber mat underneath the instruments. To avoid the direct sunlight heat, they installed additional sleeves outside the stand with 20-millimeter gaps to allow the heat to escape. To be honest, we were confident there would be no rain damage because the instruments are environmentally rated to IP64.”

After the installations, he said, “Our confidence in the durability of the instruments increased because the data processing team examined the data closely for the next six months to ensure the accuracy was constant.

“A year later, we continue to observe the raw data to make sure it still maintains the highest accuracy.  Even during periods of heavy rain, the instruments were still monitoring perfectly.  After a year of monitoring, we can attest that it is a good and reliable product,” Lim said.

“MSP owns more than 80 instruments now. Regarding our customer’s concerns about whether MSP would be able to deliver and complete in time — the 1 meter red laser guide and auto lock center gave us a lot faster results without having to look into the instrument.” 

Lim said, “With the combination of instruments and customized software, we have a decided edge over our competitors.”