La. Admin. Code tit. 43 § XXVII-1511

Current through Register Vol. 50, No. 12, December 20, 2024

Section XXVII-1511 - Topographic Mapping

A. In addition to the requirements for planimetric maps set forth above, topographic maps shall be prepared to include the following information:

1. contour lines shall be shown at vertical intervals established and specified by the responsible contracting authority. Every fifth contour line will be coded as an index contour which can be symbolized as a line of heavier weight than that of intermediate contours and shall be expressed as a heavier weight line on the digital data base hard-copy delivery maps. Index contours shall be labeled inside a "break" in the line every 6 to 12 inches at map scale. In those areas where vegetation prohibits accurate plotting of contour line elevations, the contour line elevations will be interpolated as accurately as possible from spot elevations measured photogrammetrically in places where the ground is visible. All contour lines will be solid and unbroken except where they pass through dense ground cover, in which case dashed lines must be used;

2. spot elevations will be determined photogrammetrically and shall be placed at hilltops, saddles, ridgelines, bottoms of depressions, intersections of principal streets, intersections of highways, ends of bridges, and water levels of lakes, reservoirs and ponds. Spot elevations shall also be determined and placed at maximum 400-foot intervals along the tops of all levees and floodwalls within the project area. In areas where contours are more than one inch apart at map scale, additional spot elevations shall be shown at approximately 1-inch intervals to accurately portray the character of the topography throughout the project area;

3. auxiliary heights shall consist of the photogrammetric determination of the heights of buildings, wooded areas, signs, billboards, towers and other specified features at the discretion of the responsible contracting authority. Auxiliary heights are intended to be an approximate representation of the vertical character of such features for nonprecision applications.

B. The primary topographic features to be mapped are identified within §1527, Appendix A, included herewith. Photo identifiable features required by the responsible contracting authority and not specifically listed in §1527, Appendix A, shall also be captured and categorized.

C. Each topographic feature mapped will be identified and stored digitally by a specific feature code as listed and described within Chapter 19. Any topographic features when identifiable which are not included within the list of feature elements shall be defined by appropriate outline, symbol and/or annotation by using feature code additions to the data aggregation.

La. Admin. Code tit. 43, § XXVII-1511

Promulgated by the Office of the Governor, Division of Administration, State Land Office, LR 17:968 (October 1991).

AUTHORITY NOTE: Promulgated in accordance with R.S. 50:171.