Chapter 12.20
CONSTRUCTION AND RECONSTRUCTION OF ROADWAYS AND BRIDGES
Sections:
12.20.010 Purpose.
The purpose of this chapter is to establish Black Hawk County’s policy for the construction of roads, reconstruction of roads, construction of bridges, reconstruction of bridges and other roadway and drainage features associated with road and bridge construction. [Ord. 137 § 1, 2015.]
12.20.020 Level of service.
The level of service shall be based on traffic counts, pavement type, roadway geometrics and other data used in accepted engineering design as established by the County Engineer, Iowa Department of Transportation and the Federal Highway Administration. [Ord. 137 § 2, 2015.]
12.20.030 Design criteria.
In implementation, this policy shall set the minimum design standards that Black Hawk County will follow in the construction or reconstruction of roads and bridges. These criteria shall be based on accepted engineering practices and standards established by the Iowa Department of Transportation and the Federal Highway Administration.
The County Engineer shall assure the minimum design standards established herein are adhered to in a uniform manner unless, in his or her professional judgment, a deviation from standards is warranted. Minimum design standards are not subject to discretionary enforcement. Any deviations must be documented as unreasonable and or impossible to implement by the County Engineer and/or the County Board of Supervisors.
A. Paved Routes.
1. New and Reconstruction Pavement.
a. New pavement shall be constructed with a minimum of 24-foot-wide pavement and granular shoulders.
b. Intersections with nonpaved roads shall have pavement extended back onto the intersecting road 50 feet beyond the end of the intersection radius.
c. Paved shoulders and edge line rumble strips shall be constructed if crash data warrants based on accepted HSIP and TSIP cost/benefit analysis.
d. Rumble strips shall be installed on all approach stop situations.
e. Life cycle cost analysis may be considered for pavement type selection.
f. Subdrains will be installed along both sides of paved roads.
2. Rehabilitation of Pavement.
a. Paved roads shall be rehabilitated with a 22-foot-wide pavement or to the previous pavement width, whichever is greater, with granular shoulders.
b. Intersections with nonpaved roads shall have pavement extended back onto the intersecting road 50 feet beyond the end of the intersection radius.
c. Rumble strips shall be installed on all approach stop situations.
d. Previous clear zone and shoulder widths shall be maintained.
B. Unpaved Roads.
1. Gravel Roads.
a. New or reconstruction of a gravel road shall have a 28-foot finished top, including shoulders. Roadway shall have a minimum four-inch gravel surface.
b. Rehabilitation of a gravel road shall be to the previous width.
2. Class B and C Roads. Class B and C roads will be built to the minimums as outlined by Iowa Code.
C. Bridges and Drainage Structures.
1. Paved Routes.
a. Bridges on paved routes shall be built with a minimum width of 30 feet. Wider structures will be installed when there are issues relating to oversized vehicles, pedestrian facilities, bicycle usage or other issues where the additional width is warranted.
b. Culverts under paved roads shall be concrete.
c. Pipe culverts larger than 54 inches in diameter may be substituted with reinforced box culverts.
d. Design for drainage structures will be governed by accepted hydraulic design standards. Input from IDNR, Corps of Engineers, Iowa DOT, NRCS, or USGS will be considered when determining the size and type of the structure to be placed.
e. Guardrail shall be installed that meets accepted design standards and that meets current crash test ratings from the FHWA.
2. Unpaved Routes.
a. Bridges shall be a minimum width of 30 feet on gravel roads. Bridges on dead end roads may be narrower.
b. Culverts shall be metal or concrete.
c. Design for drainage structures will be governed by accepted hydraulic design standards. Input from IDNR, Corps of Engineers, Iowa DOT, NRCS, or USGS will be considered when determining the size and type of the structure to be placed.
3. Class B and C Roads. Class B and C roads will be built to the minimums as outlined by Iowa Code.
4. Entrance Bridges.
a. Any and all bridges/drainage structures that are fully or partially in the road right-of-way that serve as entrances to private property from the public roadway shall be considered the jurisdiction and responsibility of the County.
b. Culverts shall be metal or concrete. [Ord. 137 § 3, 2015.]