Looking for some prelim costs for three types of retaining structures soldier pile wall/timber lagging, sheet pile wall, and MSE. Wall is 5 m high, fill side, sandy soils.
A cost per ft2 or m2 of wall face would be preferred.
Cost estimating is a pretty tough without specifics. The unit cost for 1,000 SF is much different than 10,000 SF. A private sector fill wall with on-site soil may be nearly half the price of a DOT wall with all granular backfill.
If $15/SF - $50/SF is close enough, then you are done.
For MSE walls: Geosynthetic reinforced block walls are typically $18-$28 per square foot of face. Metal reinforcement concrete panel walls are typically $35-$65/sf of face.
If it is a temporary structure (less than 3 years) you can build a temporary geosyntethic wrap faced MSE wall for $8-$15/sf of face.