LARIMER COUNTY RURAL AREA ROAD STANDARDS

More documents

Recommendations

Info

Appendix G – Design and Construction Standards for Private Local Access RoadsSection G.7 Road Design StandardsG.7.2 Road GradeRoad design must incorporate a maximum longitudinal slope of 8% (10% inmountainous terrain). Road designs exceeding these longitudinal slopes must ensurethat other safety and site disturbance guidelines are not compromised. Wheretopography requires, steeper grades may be necessary. The Engineer may grantdeviations in writing for unusual cases in mountainous or hilly terrain. However, theaverage grade for 200 feet should not exceed 12%.G.7.3 Horizontal Road CurveRadii of curvature on centerlines may be a minimum of 100 feet (60 feet in steep terrain),so long as adequate sight distance exists to allow a safe stopping distance.Mountainous terrain may require a deviation from this standard if topography is steep.The Engineer must approve such variance.G.7.4 Vertical Road CurveFor safety reasons, design of crest vertical curves (top of hill crests) must be based onthe design speed of the road. The design speed must take into account sight distancelimitations which result from extreme crest vertical curves. Correspondingly, sag verticalcurves (bottom of hill) must also be designed based on the design speed, such thatheadlight visibility will not be compromised in nighttime or dim light conditions.Recommended design speed for most local access roads is 15 mph in steep,mountainous areas and 25 mph in rolling to flat areas.G.7.5 Road IntersectionsIntersections should be within ten degrees of perpendicular for at least 50 feet fromintersection centerlines with adequate sight distance both directions. If topographyallows, grades should flatten to 3% or less for at least 50 feet approaching intersections.G.7.6 Dead End RoadsDead end multiple access roads must be constructed with a vehicular turnaround area atthe end or within the last 600 feet of roadway. Single access roads exceeding 600 feetin length should incorporate this standard as well. Turnarounds may take a number offorms (Figure 2), including a traditional cul-de-sac bubble, a hammerhead or “T” shape,or a turning loop. Cul-de-sac bubbles and turning loops must have a minimum radius of40 feet. T’s must have a minimum length of 35 feet on both sides. For roads narrowerthan 20 feet, turnouts must be provided at approximately every 600 feet of road. Greaterdistances may be allowable if good sight distance is maintained between adjacentturnouts. The turnouts must be constructed to allow turning movements to be made byemergency vehicles (Figure 2). Turnouts must be an all weather road surface at least 8feet wide and 30 feet long.Note: Though not a requirement in the design for 20 ft wide roads, turnouts should beconsidered if the road is the single access and egress point to the parcels served.G.7.7 Cuts and FillsRoadways should follow existing contours to the extent possible. Roadway cuts andembankments should be considered only to the extent they are necessary to maintainLarimer County Rural Area Road Standards Page G-5October 22, 2007
Appendix G – Design and Construction Standards for Private Local Access RoadsSection G.7 Road Design Standardssafe geometric conditions for the design speed. Construction of cuts and fills in thesecases must be constructed to the following requirements to maximize the safety andintegrity of such work.G.7.7.1 Cutsa. General. Unless otherwise recommended in an approved soils engineeringor engineering geology report, cuts must conform to the provisions of thissection.b. Slope. The slope of cut surfaces must be no steeper than is safe for theintended use and must be no steeper than 1 unit vertical in 1.5 unitshorizontal (66.7% slope) in common soil. Cut slopes in competent rock maybe vertical when less than 3 feet high. Cut slopes in competent rock greaterthan 3 feet high and less than 8 feet high must be no greater than 1 unitvertical to 3 unit horizontal. Cut slopes greater than 8 feet high, or whereunstable or compromising geology occurs, may require a soils engineering oran engineering geology report, or both, stating that the site has beeninvestigated. Such reports must provide a recommended slope configurationto stabilize the constructed cut. When required by the Engineer, the reportmust be prepared and signed by an individual licensed by the state toprepare such plans and specifications. Construction of such cut slopes mustconform to the recommendations of the report.Cut slopes must be seeded to reestablish appropriate vegetative cover tomaximize slope stability and minimize erosion. Existing topsoil on the sitemust be saved and stockpiled for dressing the slope prior to seeding.Mulching of the soil surface after seeding is required to minimize erosion andprotect seeds while germination and plant establishment take place. Theserequirements may be subject to appeal when slope material not conducive toplant growth and establishment make it inappropriate. In these cases it maybe necessary to use other physical or mechanical means to stabilize theslope material. Best Management Practices (BMP) and information aboutseeding and revegetation are available in the Larimer County Storm WaterDesign Standards. Copies are available at the Larimer County EngineeringDepartment.G.7.7.2 Fillsa. General. Unless otherwise recommended in an approved soils engineeringreport, fills must conform to the provisions of this section.b. Preparation of Ground. Fill slopes must not be constructed on naturalslopes steeper than 1 unit vertical in 2 units horizontal (50% slope). Theground surface must be prepared to receive fill by removing woodyvegetation such as shrubs, topsoil and other unsuitable materials andscarifying to provide a bond with the new fill. Where slopes are steeper than1 unit vertical in 5 units horizontal (20% slope) and the height is greater than5 feet, stability must be achieved by benching at the toe into sound bedrockor other competent material.c. Fill Material. Composition of fill material must follow these requirements:i. Detrimental amounts of organic material will not be permitted in fills.Larimer County Rural Area Road Standards Page G-6October 22, 2007
Page 1 and 2:
LARIMER COUNTYRURAL AREA ROAD STAND
Page 3 and 4:
Table of Contents3.3.11 Typical Str
Page 5 and 6:
Table of ContentsCHAPTER 8 - ENVIRO
Page 7 and 8:
Table of Contents12.3.7.2 Conventio
Page 9 and 10:
Table of ContentsG.7.12 Other Permi
Page 11 and 12:
Chapter 1 - General InformationSect
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Chapter 2 - Submittal ProceduresSec
Page 19 and 20:
Chapter 2 - Submittal ProceduresSec
Page 21 and 22:
Chapter 3 - Submittal Requirements
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Chapter 4 - Road Design and Technic
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
4.9.1.7 Design VehiclesChapter 4 -
Page 37 and 38:
Page 39 and 40:
CHAPTER 5 - GEOTECHNICAL STANDARDS
Page 41 and 42:
Chapter 5 - Geotechnical Standards
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Chapter 6 - STORMWATER MANAGEMENTSe
Page 51 and 52:
Chapter 7 - Bridges and Major Drain
Page 53 and 54:
Chapter 8 - Environmental and Agric
Page 55 and 56:
Chapter 8 - Environmental and Agric
Page 57 and 58:
9.1.3 DefinitionsChapter 9 - Roadwa
Page 59 and 60:
CHAPTER 10 - ACCESS REQUIREMENTS AN
Page 61 and 62:
Chapter 10 - Access Requirements an
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
CHAPTER 11 - ACCESS AND UTILITY PER
Page 73 and 74:
Chapter 12 - Right of Way Permittin
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94: Appendix A - Definitions and Abbrev
Page 95 and 96: Appendix A - Definitions and Abbrev
Page 97 and 98: APPENDIX B - REFERENCES AND RESOURC
Page 110 and 111: APPENDIX D - CONSTRUCTION STANDARDS
Page 112 and 113: Appendix D - Construction Standards
Page 130 and 131: APPENDIX E - CONSTRUCTION TESTING F
Page 132 and 133: Appendix F - Guidelines for Traffic
Page 140 and 141: APPENDIX G - DESIGN AND CONSTRUCTIO
Page 142 and 143: Appendix G - Design and Constructio
Page 154 and 155: Appendix H - General NotesSection H
Page 162 and 163: APPENDIX I - VARIANCE REQUEST SUBMI
show all

LARIMER COUNTY RURAL AREA ROAD STANDARDS

Create successful ePaper yourself

Delete template?

Save as template?