A summary of the project

2.5 kilometers of railway substructure - 998 meters in Tunnel - 20 spans with a total length of 856 meters of special bridges - The Saray Bridge, with a length of more than 550 meters

The project involved the construction of 2.5 kilometers of railway substructure in difficult topographic and mountainous terrain. The majority of this length consisted of tunnels (998 meters in total) and special bridges (20 spans with a total length of 856 meters). The Saray Bridge, with a length of more than 550 meters (10 spans up to 95 meters and 9 piers up to 53 meters), is one of the most unique structures on the entire path. The bridge was built using the pre-stressed post-tensioned box section method with the balanced cantilever method using two 250-ton overhead form travelers (manufactured by Tossar). The Saray Bridge, with a length of more than 550 meters (10 spans up to 95 meters and 9 piers up to 53 meters), is one of the most unique structures on the entire path. This bridge was built with pre-tensioned and post-tensioned box section and balanced truss method by two 250 ton shario formwork machines (made by Tossar company).

Termination Year

In progress

Start Year


State: Ardabil

Doing reverse engineering on a European model with the NRS brand and making a Chario mold with the Tosar company brand (TRS) with the capacity to build segments up to 250 tons and deck dimensions up to 13.6 meters from 2017 is a big step towards the goals of resistance economy and production improvement It is considered national knowledge and skill for the Iranian engineering community, and fortunately, its installation and perfect performance on top of the highest foundation of the Saray Bridge; The introduction became a lasting achievement and many subsequent actions for the construction of Shario bridge construction equipment in the country. Tosar company, while taking a sample from a foreign sample, carried out the special design of the mold parts according to the specifications of Paul Sarai in its technical book, and by producing shop drawings and using the capacity of the most famous industrial companies, cut and punch the sheets of this mold with High quality and speed started.

As one of the most challenging railway projects in the country, the Middle-Ardabil railway is 175 kilometers long, while passing through difficult mountain routes, it is considered one of the unique railway lines in the country in terms of the amount and type of technical infrastructure, which is the largest tunnel along the route. 1200 meters and the most special bridge (Saray bridge) with a length of 556 meters was built by Tossar company.
The Saray Bridge is located between two tunnels, in a mountain valley, adjacent to the Ghazal Ozen River and overlooking the Shahriar Dam lake. The concrete deck in the majority of the length of this bridge is made by the method of balanced truss and by advanced molds which are famous in today's bridge construction technology as Shario molds, with a worthy architectural design and unparalleled structural quality.

A summary of the project

Due to the special conditions of this bridge, at the beginning of the project, concrete experts were employed by Tosar Company to conduct a special monitoring of the Saray Bridge concrete in addition to the usual quality control of the workshop that takes place in all projects. The specialty of this group is the optimization of the mixing plan and the production of high-strength concrete for special structures; which began to operate with the aim of producing concrete with maximum strength and durability and as a result increasing the life of the Saray bridge and also predicting special considerations for obtaining resistance in the implementation method of Shario.

Considerations regarding the durability of the concrete of this bridge, especially in terms of the proximity of the foundations to future reactive factors in the dam lake and the discussion of alkaline reactivity of the aggregates, in addition to the necessary operational considerations in terms of the efficiency and fluidity of the concrete for concreting in the deck of this bridge at the height above the foundations Also, in the sections with reinforcement and cabling with high density and the sheath path of multiple prestressing cables along the length of the spans, it required different conditions to be considered for the mixing plan of this bridge compared to the mixing plan of common concretes used in the axis.
On the other hand, for the implementation of the bridge deck, which was often implemented as a balanced tower with shario formwork, quick formwork and project progress required obtaining high strength quickly.