It is TT gauge 1:100 scale, slightly bigger than TT120 scale, but could also be used on a TT120 scale layout.
1:120 TT Gauge Double Track Bowstring Bridge 3D Printed In Grey Free Delivery
TT Scale Double track Double span Girder Bridge with supports 3D printed
Hornby TT8002 TT Gauge Straight Track - Extra Track Pieces for Model Railway Sets, Toy Train Track Pieces, Includes Straight Model TT Track - Hobbies for Men - Scale 1:120, Brown
TOMIX N Gauge Double-Track Girder Bridge II Set Two Double-Track PC Piers 3067
Hornby TT9019 TT Gauge Double Engine Shed Red Brick Collection