| 摘要 |
A safety pole which is yieldable has been roll formed to a polygonal cross-section and has only one longitudinal joint (11). Alternatively, two halves can be roll formed separately and welded together to a pole. A few or all polygon sides or the corners have inward folds (31-35) which provide three layers of sheet and stiffens the pole, but does not prevent the pole from being yieldable when run into by a vehicle. The inward fold forms a centre slot (30) which is aired by the wind. The stiffeners can alternatively be situated externally instead of internally. |
