1.1　CRTSⅢ Track Structure on Bridge

CRTSⅢ slab ballastless track structure on bridge is mainly composed of 4 parts，as is shown in Figure 1，they are respectively from top to bottom：（taking straight line as an example）200mm thick two-way prestressed track slab，90mm thick self-compacting concrete structural layer，isolated layer and elastic layer，and 200mm thick（center of straight line section）concrete base.

1.Prestressed track slab

The basic types of track slab on bridge consists of 5600mm，4925mm and 4856mm，the length of nonstandard track slab on abutment and nonstandard simply supported beam shall be determined according to slab distribution design，its width is 2500mm and thickness is 200mm，and under the track slab shall be arranged with portal connecting reinforcement.The curved shape track slab shall be laid in curve section，the laying principle is that the intersection point of the center line of the second pair rail bearing platform at tip part of track slab and the center line of the track slab shall be arranged on track center line.70mm transverse gap shall be arranged between adjacent track slabs.The finished track slab is designed with longitudinal and transverse two-way prestress，according to different sequence of prestress applied in construction process，the track slabs are divided into pre-tensioning prestressed concrete track slab and post-tensioning prestressed concrete track slab.Zhengzhou-Xuzhou passenger dedicated railway adopts pre-tensioning prestressed concrete track slabs.

Figure 1　Sketch Map for Structure of CRTSⅢ Slab Ballastless Track on Bridge（Straight Line Section，Unit：mm）

2.Self-compacting concrete structural layer

To consolidate the fine adjustment result for track slab-the spatial geometrical state of track slab，as well as the connection of track slab with the bed plate，90mm thick self-compacting concrete structural layer shall be arranged，its length and width are the same as those of track slab.Inside the structural layer is designed with crack-prevention rebar meshes，which is connected and fixed with the reinforcement in the base limit groove；the self-compacting concrete shall be poured through the grouting holes reserved on track slab.

3.Isolated layer and elastic layer

The base and bottom groove are set with intermediate isolated layer（geotextile），around the groove is set with elastic layer，which can meet the requirement for structural stress，deformation and material durability.

4.Concrete base

The bed plate corresponds to the track slab on bridge，forming unit structure.Every base unit is set with 2 limit grooves，and one 20mm wide transverse expansion joint shall be set whose length corresponds to one piece of track slab.The expansion joint shall be filled with polystyrene foam plastics board，and sealed with joint material.The superelevation on curve at bridge section shall be set on the base.