What does RRR mean?

RRR stands for “Reinforced soil Road structures with Rigid facing”
RRR are reinforced structures that include embankments, retaining walls,
water-front structures, bridge abutments, bridge systems etc. constructed for railways,
highways and others.
RRR reinforced soil structures comprises four sub-systems, A to D:
Category Structure type
RRR-A Reinforced-soil bridge abutments & bridge systems
RRR-B Geosynthetic-Reinforced Soil (GRS) retaining walls
RRR-C Nail-Reinforced Soil (NRS) retaining walls
RRR-D GRS structures to prevent water-front disasters
OHTERS GRS Box Culvert / GRS Tunnel Entrance

RRR-AReinforced-soil bridge abutments & bridge systems

・GRS Bridge Abutments, using bearings to support a simple girder.

・GRS Integral Bridges and NRS Integral Bridges structurally integrating the girder respectively, to the top of FHR facing connected to GR backfill, and to the top of RC abutment connected to nailed backfill.

RRR-BGeosynthetic-Reinforced Soil (GRS) retaining walls

・GRS retaining walls (RWs) with full-height rigid (FHR) facing

・GRS RWs with FHR facing can support railway tracks or roads arranged close to the wall face. They can also support continuous RC slab railway tracks and external loads acting on, or close to, the facing.

RRR-CNail-Reinforced Soil (NRS) retaining walls

・Natural slopes and embankment slopes are cut to vertical walls by reinforcing slopes with medium to large diameter nails using full-height rigid facing.

RRR-DGRS structures to prevent water-front disasters

・Water-front GRS structures to prevent and mitigate disasters caused by scouring, erosion and overtopping flow by flood, storm and tsunami.

GRS Tunnel Entrance
GRS Box Culvert


Brief history

Start of basic research at Institute of Industrial Science, the University of Tokyo
Start of research at Railway Technical Research Institute, Japan
Application for the first patent (15 July)
Patent No.1870191 for "Embankment stabilization method by soil-reinforcing and structures constructed by this method"
First prototype of GRS RW structure by RRR-B technology at Tennoji station, Osaka (August)
Establishment of Association of RRR Construction System (12 July)
Certificate of technical evaluation (No.0505) by Japan Institute of Country-ology and Engineering (31 March) : RRR-GRS Retaining Wall system (RRR-B system)
Certificate of technical evaluation (No.1403) by Advanced Construction Technology Center (28 November): Radish Anchor (Large-diameter nails) method (RRR-C system)
Publication of a book entitled by "All of the new reinforced soil retaining walls" by General Civil Engineering Institute Co.,Ltd. [Sougou Doboku Kenkyujo] (25 October)
Establishment of Radish Anchoring Section (June)


RRR structures are hybrid structures integrating a rigid facing and a reinforced soil body. The RRR structures can exhibit outstanding performance by combining advantageous features of rigid facing and reinforced soil body.
The basic principles of the RRR construction system are shown below:

Advantages of rigid facing
★High strength & high rigidity
★High durability
Advantages of
Reinforced Soil Body
★Stable behavior of soil
★No use of pile foundation
★Fast construction
★Less carbon dioxide emissions
Staged Construction and Firm Connection between Rigid Facing and Reinforcements
Embankments RRR-A,B & D
Hybrid structure integrating
a rigid facing and a reinforced soil body
Performance-based design
(in particular, against high seismic loads)
※ The FHR facing is constructed at the last stage.
Natural slopes
embankment slopes