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Maximum grade: The maximum permissible vertical angle, or grade, along the highway is determined from terrain and design speed, [4] with up to 6% generally allowed in mountainous areas, 5% in rolling terrain, and 4% on level terrain. An additional 1% is allowed in urban areas.
Grade is usually expressed as a percentage - converted to the angle α by taking the inverse tangent of the standard mathematical slope, which is rise / run or the grade / 100. If one looks at red numbers on the chart specifying grade, one can see the quirkiness of using the grade to specify slope; the numbers go from 0 for flat, to 100% at 45 ...
The alignment is the route of the road, defined as a series of horizontal tangents and curves. The profile is the vertical aspect of the road, including crest and sag curves, and the straight grade lines connecting them. The cross section shows the position and number of vehicle and bicycle lanes and sidewalks, along with their cross slope or ...
The Michigan State Highway Department (MSHD) was created in 1905, and the department paid counties and townships to improve roads to state standards. On May 13, 1913, the State Reward Trunk Line Highways Act was passed, creating the State Trunkline Highway System.
The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public ...
The measurement of IRI is required for data provided to the United States Federal Highway Administration, [1] [9] and is covered in several standards from ASTM International: ASTM E1926 - 08, [10] ASTM E1364 - 95(2005), [11] and others. IRI is also used to evaluate new pavement construction, to determine penalties or bonus payments based on ...
It is typically a long, sand- or gravel-filled lane connected to a steep downhill grade section of a main road, and is designed to accommodate large trucks or buses. It allows a moving vehicle's kinetic energy to be dissipated gradually in a controlled and relatively harmless way, helping the operator stop it safely.
The county-designated highways in Michigan comprise a 1,241.6-mile-long (1,998.2 km) system of primary county roads across the US state of Michigan. Unlike the State Trunkline Highway System , these highways have alphanumeric designations with letters that correspond to one of eight lettered zones in the state.