Bridge Study for the Proposed Matun and Lakan Bridges

The purpose of the Bridge Study is to develop construction cost estimates for the bridges, which are proposed to cross an existing wadi subject to flooding. The study is based on the Bridge Type Study report prepared for the Sagai crossing in Khost province, dated March 5, 2011. The superstructures for each bridge were analyzed for two design vehicles: an AASHTO HS25 truck and an MLC-70 (both a tracked and wheeled vehicle meeting the rating of a 622.7 kN (70-ton) Military Load Combination). The MLC-70 vehicle selection, as directed by the Client, accounts for a response vehicle carrying a disabled MRAP. The traditional solution to a long bridge crossing is using a concrete deck, supported on girders, supported on piers and abutments. Since these girder types are not locally available, rectangular concrete beams are used. Rectangular concrete beams can be precast or cast-in-place, and can accommodate spans up to approximately 18.3 m (60 feet). The following table summarizes the span configuration and superstructure depth for the two bridges: | Bridge | Span Length (m) | Number of Spans | Proposed Superstructure Depth (m) | | --- | --- | --- | --- | | Matun | 15.0 | 12 | 1.47 | | Lakan | 15.0 | 10 | 1.47 | Both bridges are based on the superstructure supported on reinforced concrete piers and abutments. This type of substructure has several advantages, including longest span lengths, minimizing the number of piers in the channel, minimizing the required excavation, and meeting seismic design requirements for the region. The following table provides an Order-of-Magnitude construction material quantity summary for the major items of both bridges: | Bridge | General Excavation Volume (cm) | Backfill Volume (cm) | Total Concrete Volume (cm) | Total Reinforcing Steel Weight (kg) | | --- | --- | --- | --- | --- | | Matun | | | | | | Lakan | | | | | The construction quantities for the bridges are summarized in the table above. The quantities are based on the design parameters and assumptions presented in the report. The quantities are subject to change based on the results of the geotechnical investigation, which will be performed during the next phase of the project. The report includes a list of figures and tables, including the general plan and elevation of the Matun and Lakan bridges, the abutment plan and elevation, and the superstructure details. The report also includes a bill of quantities (BOQ) for each bridge, which provides a comprehensive list of the construction materials and quantities required for each bridge. The Bridge Study is based on preliminary analyses and design calculations performed for the Sagai bridge crossing. The study is intended to provide a preliminary estimate of the construction costs for the Matun and Lakan bridges. The study will be updated based on the results of the geotechnical investigation and other design parameters.