INTRODUCTION This chapter presents guidance on the application of geometric design criteria to facilities functionally classified as local roads and streets. Local roads and streets constitute a high proportion of the roadway mileage in the United States. They provide access to farms, residences, businesses or other abutting properties. Traffic volume greater than 400 veh/day is one of the design criteria for design of local roads and streets. Roads less than 400 veh.//day are not applicable to the design criteria in this chapter. AASHTO is working on the design of these types of roads. This chapter discusses three types of roadways: Local Rural Roads, Local Urban Streets, and Special Purpose Roads

LOCAL RURAL ROADS Constituted by the majority of two lane local roads Design ADT20 years after the date of completion of construction or 20 years from the current year Design Speedsee Exhibit 5-2 Sight Distancesee Exhibit 5-2 for SSD see Exhibit 5-3 for PSD GradesMaximum grade see Exhibit 5-4 Minimum grade see P242.

Alignmentconsistent and smooth two-lane alignment Cross Slope1.5 –2 for high-type pavement 2-6 for low-type pavement see Exhibit 5-5 Superelevatione no more than 12% generally e no more than 8% at snow and ice conditions Structure Bridges to remain Standard Specifications for Highway Bridges In placesee Exhibit 5-6 and Exhibit 5-7 Vertical Clearanceat least 4.3 m LOCAL RURAL ROADS

ROW WidthShould be acquired to accommodate construction, adequate drainage, and proper maintenance of a highway ForeslopeNot steeper than 1V:2 H The ditch bottom and slopes should be rounded. The backslope should not exceed the maximum required for stability. H. Clearance to Obstructions2-3 m clearance from the ETW Curbssee curbs in the Local Urban Streets Intersection Designno intersection on a short-crest vertical curve or on a sharp horizontal curve. More on Chapter 9 on Intersections Design LOCAL RURAL ROADS

A local urban street is a public roadway for vehicular travel including public transit and refers to and includes the entire area within the ROW. It also serves pedestrians and bike traffic and accommodate public utility facilities in the ROW. Design ADT2 or 4 lanes = f(traffic volume) 10 or 20 years after the date of completion of construction Design Speed30 –50 km/h. Not a controlling factor in design. In the typical street grid, the closely intersections limit travel speeds, making the design speed less important. Sight Distance30 – 60 m depending on design speed (see Exhibit 3-1) Grades< 15% General 8% for commercial and industrial areas desirable 0.3% min for streets with outer curbs LOCAL URBAN STREETS

Alignmentfit with the existing topography to minimize the needs for cuts or fills; discourage through traffic Min. Radius of a horizontal curve 30 m cannot be less than 25 m for a 30 km/h design speed Cross Slope1.5 – 2 for high-type pavement 2-6 for low type pavement SuperelevationUsually superelevation is not needed in residential and commercial areas. When superelevation is used, e max = 4 Number of LanesAt least one unobstructed moving lane must be ensured even where parking occur on both sides. Roadway Width3.0 – 3.6 m/lane LOCAL URBAN STREETS

Parking LanesA parallel parking lane a min. 2.1 m wide should be provided on one or two sides in residential areas. 2.4 m for commercial and industrial areas. MediansMedian openings should be located with adequate sight distance. Shape and length of the median openings = f(median width, and vehicle type to be served) CurbsStreets normally are designed with curbs. The curbs are 100 mm to 150 mm high. Vertical curbs with 150 mm high or more should be offset at least 0.3 m. Drainagegutter min. grade = 0.3%. Surface water are collected by curbs, gutters, and ditches and conveyed to a drainage system Cul-De-Sac and TurnaroundMin. outside radius 10 m – 15 m. See Exhibit 5-8. LOCAL URBAN STREETS

AlleysAlleys provide access to the side or rear of individual land parcels. They are a narrow ROW and range from 5-6 m (width) in residential areas and up to 10 m in industrial areas SidewalksDesirably on both sides of streets. Min. width is 1.2 m. Sidewalk Curb RampsSee AASHTO Guidelines for the Planning, Design, and Operation of Pedestrian Facilities. DrivewaysDriveway returns should not be less than 1 m in radius. Roadway Widths For Bridgessee Exhibit 5-6 H. Clearance to ObstructionsA min. 0.5 m should be provided between the curb face and obstructions. LOCAL URBAN STREETS

Vertical Clearanceat least 4.3 m Border AreaA border area should be provided along street for the safety of motorists and pedestrians as well as for aesthetic reasons. It is the area between the roadway and ROW. 1.5 m to 3.0 or wider ROW Widthvaries in order to accommodate planned roadway. Intersection Designssee Chapter 9 Street and Roadway see Exhibit 5-11 Lighting LOCAL URBAN STREETS

Special purpose roads include recreational roads, resource recovery roads, and local service roads. Recreational Roads Criteria are to protect and enhance the existing aesthetic, ecological, environmental, and cultural amenities. Recreational roads involve three types of roads: primary access roads, circulation roads, and area roads. See Exhibit Design Speed:60 km/h – primary access road 50 km/h – circulation roads 40 km//h – area roads Design Vehicle:Motor homes, vehicles with trailers, PU SPECIAL PURPOSE ROADS

Recreational Roads Sight DistanceSee Chapter 3 SSD should be measure with an eye height of 1080 mm and an object height of 1300 mm. The SSD is doubled for a two-way single lane road. See Exhibit PSD see Exhibit Gradessee Exhibit 5-15 for max grade Vertical Alignmentsee Exhibit 5-1. SSD doubled on two-way, one lane road. Horizontal Alignmente max = 6% no SE on roads with design speed of 30 km/h f different in Exhibit SPECIAL PURPOSE ROADS

Recreational Roads Number of LanesTwo-way one lane for < 100 veh/h turnouts at max. interval of 300 m should be provided when two-way and one lane is considered. Turnouts should be >3 m wide, 15 m long and a taper of 8 m at two ends. See Exhibit 5-17 Cross SectionSee Exhibit 5-18 cross slope for local rural roads are applicable Clear Recovery Zone3 m or more recovery area Roadside Slope1v:4 H Roadside Barriersee AASHTO Roadside Design Guide SPECIAL PURPOSE ROADS

Resource Recovery Roads Mining and logging roads are the resource recovery roads. Criteria are same as those for recreational roads. SEe max = 6% Gradesconsidering the requirements of large loaded vehicles Design SpeedSee Exhibit 5-19 Local Service Roads Those serving isolated areas that have little or no potential for further development. Criteria are same as those for recreational roads. SPECIAL PURPOSE ROADS