Table: covered_bridge_specs
Columns: length_feet_m
width_feet_m
load_short_tons_mt
truss_type_s
year_built
source_year

Question: What is the width feet in meeters for the truss with a source of nbi (2009)?
SQL: SELECT "width_feet_m" FROM covered_bridge_specs WHERE "source_year" = 'nbi (2009)'

Question: What is the width for hte truss with a source of zacher (1994)?
SQL: SELECT "width_feet_m" FROM covered_bridge_specs WHERE "source_year" = 'zacher (1994)'