TEHRAN, Jan. 5 (Mehr News Agency) -- A deviation from the correct course in digging the western end of a tunnel for the Isfahan Metro near the Si-o-Se Pol Bridge is threatening the historic Safavid monument.

Isfahan's Si-o-Se Pol Bridge - click image for high resolution

The tunnel-boring machine (TBM) is reported to have deviated from its proper route and bumped into a ramp and a lower part of the bridge.

Over the past week, many cultural heritage enthusiasts and experts have protested against possible negligence by the tunnel contractor following publication of relevant media reports about the incident.

Consequently, the Alamut Company, in charge of drilling the tunnel for the Isfahan Metro project, invited a number of reporters to visit the site. However, they were escorted to the eastern end of the tunnel instead of the western end where the incident is reported to have occurred.

During the visit, project manager Babak Rostami said the route deviation was caused by an error in the TBM and considered the problem to be a mundane, every day issue in tunnel-boring.

The error occurred because of differences in the density of the earth, he explained and added, "When a TBM drills a tunnel, it may deviate if it encounters earth with low and high density simultaneously."

Si-o-se Pol, also known as the Allahverdi Khan Bridge, is one of a small number of Isfahan's historical bridges spanning the Zayanderud River.

The construction of the bridge began in 1602 by order of the Safavid king Shah Abbas I.

The Isfahan Metro officials said that the historical city's metro will be operational by 2012. Other metro lines under construction are threatening monuments located on Chahar-Bagh Street as well as in Naqsh-e Jahan Square, a complex of Safavid-era monuments registered on the UNESCO World Cultural Heritage List.

In 2001, UNESCO rejected the Isfahan Municipality's request to construct tunnels beneath Chahar-Bagh Street and Naqsh-e Jahan Square.

Despite rejection by UNESCO and opposition by the Isfahan Cultural Heritage, Tourism and Handicrafts Department, the project's tunnels were bored.

Experts believe that vibration caused by metro trains passing underneath the monuments will cause damage to nearby historical sites.

... Payvand News - 01/05/10 ... --