Relocating Ramses II with the Help of LabVIEW and PXI

Author(s):
Tamer Elnady - Ain Shams University Sound and Vibration Lab

Industry:
Research

Products:
PXI/CompactPCI, LabVIEW

The Challenge:
Moving a priceless, 83 ton statue over a distance of 35 kilometers without subjecting it to unnecessary damage.

The Solution:
Developing a highly sensitive vibration monitoring system using LabVIEW and PXI to indicate when the statue is in danger of being damaged.

In 1882, a massive statue of King Ramses II was discovered at the Great Temple of Ptath in Egypt. The granite statue weighed 83 tons and was in six separate pieces that stood 12 meters tall. Attempts to re-erect it failed until 1955 when it was successfully relocated to Bab Al-Hadid, later renamed Ramses Square, in Cairo. At the time, this was an ideal location, surrounded by trees and close to a very famous fountain. However, in recent years air pollution from heavy city traffic and vibrations from the subway has taken its toll on the statue.  To protect the statue from these elements, the decision was made to relocate it to the site of the planned Egyptian Museum, scheduled to open in 2011.

 
After the decision was made by archeologists and the government to move the statue, the challenge became figuring out exactly how this would be accomplished. Researchers from Ain Shams University proposed a method based on a zero-risk procedure. A cage would be erected around the statue and fixed to its concrete base. The statue would then be lifted from below. This cage is carried on four spherical bearings to give the statue the freedom to always retain its vertical position regardless of the inclination of the road (acting as a gyroscope). The main frame of the transporter would be placed on two trailers, each with 64 wheels. Because this was the first time this method would be attempted, and because of the historical significance of the statue, a fake statue was built in order to conduct a simulated transport. 

One concern was the condition of the steel rods joining the six pieces of the statue together. There was a fear that the strength of these joints might have deteriorated over time. In order to insure that the whole process would not harm the statue, we decided to perform vibration measurements to monitor any extreme forces that might be transferred to the statue. Vibration measurements were required during three stages. The first stage is to monitor the vibrations during the construction works around the statue, preparing the location for the erection of the transporter. The most dangerous process was digging concrete pillars into the ground to support a huge concrete floor supporting the transporter, and drilling holes in the concrete base of the statue itself. This second stage, which took place while transporting the fake statue, was to ensure that the vibrations that reach the statue in the transporter would be acceptable. The third stage was during the transportation of the original statue. An online monitoring system was installed and the vibrations would be continuously monitored so that any strange observations would result in a notification to stop the transporting process.

A National Instruments PXI measurement system was used to collect data from the different accelerometers during all stages. The PXI system was chosen because of its high channel count and the versatility of being able to program the measurement using LabVIEW. It also offered a rugged design suited for the harsh environment. It was programmed to sound a warning siren if the acceleration level at one of the accelerometers exceeded the pre-programmed level for this accelerometer.

For the vibration monitoring during the preparation phase, a small wooden shelter was built beside the statue to protect the PXI system from any danger. During the transportation of both the fake statue and the original, the PXI system was installed on the forward cross beam and a generator was located at the backward cross beam to provide electric power to the system. It was not possible for someone from our team to ride on one of the transporter trailers to monitor the vibration levels during the trip, so we prepared two means to communicate with the PXI remotely. The first was using a wireless LAN and the second was using a GSM modem connecting the system to the Internet. The system could be accessed through a laptop by a member of our team sitting in a bus behind the transporter to monitor any dangerous effects.

Preparing the Site
Taking measurements while preparing the statue was the most critical phase of the project. It was required that we monitor the vibrations 24 hours, 7 days a week for a couple of months during any construction activity around the statue. If the vibration level at any time exceeded the alarm criteria, the work would be stopped and the cause of the high level would be examined. Most of the alarms occurred while drilling into the concrete base directly below the statue.

Transporting the Statue
The purpose of taking measurements during this stage is to monitor the vibrations transmitted to the statue while being transported. This was done twice, during the transportation of the fake statue and the transportation of the original. We tried to maintain the same measurement points during transportation.

After setting the alarm levels, the vibration levels were continuously monitored during the construction. There were some peaks and some alarms, but most of the time the levels were acceptable. Whenever the alarm criteria are met, the work would stop and the cause of this alarm would be discussed in order to be resolved and avoided.

The vibration measurements during the transportation of the fake statue showed that the proposed transporter is safe to use for the original statue. This was an important conclusion based on the vibration measurement that helped the contractor go forward and show the measurements during the transportation of the original statue compared to the alarm levels.

This relocation process is considered a large engineering achievement in modern history and engineers and experts from different disciplines were involved. It was important to monitor the vibration levels during this critical project. The main purpose of these measurements was to ensure the safety of the statue and that any handling of the statue by the contractor will not harm it or in the worst case cause it break. This includes measurements while preparing the site, during the move of concrete duplicate, and the relocation of the original statue. The flexibility of the LabVIEW programming environment and the ruggedness of the PXI system provided an ideal solution for the safe transportation of the statue.

Author Information:
For more information on this Case Study, contact:
Tamer Elnady
Ain Shams University Sound and Vibration Lab
Cairo
Egypt
tamer@svlab-asu.com

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