D.C. Code § 9-421.02

For the purposes of computing the assessments under this subchapter, the term “roadway” shall be construed to include the gutters and curbings; provided, however, that where any permanent and new construction of curb, or curb and gutter, is laid, and the roadway of the street is not paved or repaved, or is not paved or repaved with a pavement of the character specified in § 9-421.01, the half cost of such curb, or curb and gutter, shall be assessed against the abutting property in the manner provided in this subchapter.