PURPOSE: To obtain a reticular culvert having a high strength to external pressure by a method in which synthetic resin vertical wires are set in a circular form at intervals, their facing portions are partly bound, and the periphery of the circular vertical wires is wound with spiral synthetic resin bands of a T- shaped cross section.

CONSTITUTION: Plastic vertical tubular wires 1 are set in parallel in a circular form at intervals (a), and a small number of the facing vertical wires 9 set circularly are contacted with each other. The lowest part of plastic spiral bands 2 of a T-shaped cross section is welded to the vertical wires 1 and 9 set circularly with a spacing (b) between the heads of the adjacent spiral bands 2. The deformation strength in the radial direction can be raised, the flexibility in the vertical direction can be lowered, and the flexibility in the horizontal direction can also be raised.