Highway Planning and Classification Lecture 3 PDF

3 2022-2023  Highway Planning Highway like any other Engineering project needs development planning. The planning of highways is done to achieve the following objects: 1. Planning a highway network for safe, efficient and fast movement of people and goods. 2. Keeping the overall cost of constr...

3 2022-2023  Highway Planning Highway like any other Engineering project needs development planning. The planning of highways is done to achieve the following objects: 1. Planning a highway network for safe, efficient and fast movement of people and goods. 2. Keeping the overall cost of construction and maintenance of the roads in the network to a minimum. 3. Planning for future development and anticipated traffic needs for a specific design period. 4. Phasing road development programmed from considerations of utility and importance as also of financial resources 5. Evolving a financing system compatible with the cost and benefits Water Bound Macadam roads The road mainly classified as(based on location and function): 1. National Highways: Are many highways running through length and breadth of the country. They are connecting national capital with state capitals, or major port towns border areas...etc. Roads connecting the neighboring are also called National Highway. N.Hs should be at least 2 lane wide and should have high class surface finishing. 2. State Highways: They connect important towns and cities of the state. Should be two lanes wide but if one lane wide only, it must be provided with wide shoulders, should be good surface finishing. 3. District Roads: they are the Roads, which traverse each district. These roads serve areas of production and markets. District Road are classified as: a. Major District Road: They connect areas of production and market with either a state Highway or National Highway. These Roads should be at least one lane wide and having modern type of surface finishing. b. Other District Road: These Roads are of somewhat lower specifications than major district and State Highways. These roads should have proper drainage. 4.Village Roads: These are for the village use. These connect the village with each other and also town nearby. These are generally stabilized earth roads but the metal surface is preferable to serve a more useful purpose. The construction and maintained are carried by the local district boards. 5.Express ways: These Roads are of higher class than N.H. These are such roads on which only fast moving vehicles. Expressways should be under control system and they are provided With grade separation system of all the road intersections. They have at least 4 lane Wide and have divided lanes. Roads can also be classified as urban roads and rural roads. urban roads have foot path and underground drainage system: whereas rural roads have shoulders. Side drain...etc Highway Classification Highways are classified either by: 1. The function they serve (functional classification) 2. The entity responsible for their construction and maintenance (jurisdictional classification) Two concepts are used when classifying highway by their function: Mobility and Accessibility  Mobility: Continuous travel.  Accessibility: Direct access to abutting (next to or adjacent) property. Some roads serve one of these two functions while few can satisfy both. Highway Classes Highways are classified according to their functions in terms of the service they provide.  Highways and streets are categorized as rural or urban roads, depending on the area in which they are located. This initial classification is necessary because urban and rural areas have significantly different characteristics with respect to the type of land use and population density, which in turn influences travel patterns. Urban roads comprise highway facilities within urban areas which include communities with a population of at least 5000 people. FUNCTIONAL CLASSIFICATION  Major Highway Classes 1. Arterial - High mobility - Low access - Long trip - Fast speed 2. Collector - Moderate mobility - Moderate access - Moderate trip length - Moderate speed 3. Local - Low mobility - High access - Short trip Accessibility and mobility in highway classes - Low speed  Schematic illustration of functional classification of rural highway network Schematic figure below shows functional classes for a suburban road network. Functional Systems of Urban Roads 1. Urban Principal Artesian System This system of highways serves the major activity centers of the urban area and consists mainly of the highest traffic - volume corridors. - The system serves trips that bypass the central business districts (CBDs) of urbanized areas. 2. Urban Minor Artesian System Streets and highways that interconnect with and augment the urban primary arterials are classified as urban minor arterials. - Although highways within this system may serve as local bus routes and may connect communities within the urban areas, they do not normally go through identifiable neighborhoods. - The spacing of minor arterial streets in fully developed areas is usually not less than 1 mile, but the spacing can be 2 to 3 miles in suburban fringes. 3. Urban Collector Street System The main purpose of streets within this system is to collect traffic from local streets in residential areas or in CBDs and convey it to the arterial system. - Collector streets usually go through residential areas and facilitate traffic circulation within residential, commercial, and industrial areas. 4. Urban Local Street System This system consists of all other streets within the urban area that are not included in the three systems described earlier. - The primary purposes of these streets are to provide access to adjoining land and to the collector streets. Through traffic is discouraged on these streets. Functional System of Rural Highway Roads 1. Rural Principal Arterial System This system consists of a network of highways that serves most of the interstate trips and a substantial amount of intrastate trips. -Virtually all highway trips between urbanized areas and a high percentage of trips between small urban areas with populations of 25,000 or more are made on this system. - The system is further divided into freeways (which are divided highways with fully controlled access and no at-grade intersections) and other principal arterials not classified as freeways. 2. Rural Minor Arterial System This system of roads augments the principal arterial system in the formation of a network of roads that connects cities, large towns, and other traffic generators, such as large resorts. - Travel speeds on these roads are relatively high with minimum interference to through movement. 3. Rural Collector System Highways within this system carry traffic primarily within individual counties, and trip distances are usually shorter than those on the arterial roads. This system of roads is subdivided into major collector roads and minor collector roads. 4. Rural Major Collector System Routes under this system carry traffic primarily to and from county seats and large cities that are not directly served by the arterial system. The system also carries the main intra-county traffic 5. Rural Minor Collector System This system consists of routes that collect traffic from local roads and convey it to other facilities. - One important function of minor collector roads is that they provide linkage between rural hinterland and locally important traffic generators such as small communities 6. Rural Local Road System This system consists of all roads within the rural area not classified within the other systems. These roads serve trips of relatively short distances and connect adjacent lands with the collector roads. Rural Highway network Urban Road Patterns:  Although road patterns in a country are historically inherited, later additions can be planned bearing in mind the requirements of the day.  Road patterns are of great use in urban highway planning. The choice of a road pattern depends upon the extent of land use or the distribution of residential, industrial and business areas in a city, the nature of the terrain, and the planner’s preferences. The main patterns in use in urban areas are: 1. Grid Iron Pattern: This is also known as rectangular or block pattern and is perhaps the simplest (Fig. 1.5). The Romans preferred it, as have the Americans who adopted it in many of their cities. This is easy to set out in straight lines and rectangular co-ordinates, and is suitable for flat terrain. 2. Radial Pattern  in this pattern, roads emanate from a central focal area, which may be a business center or an important public building. In order to ease the congestion in the focal area, ring roads are provided; there can be several such roads—inner, intermediate and outer—depending on the requirements of the traffic.  The shape of a ring road may be round, square, or elongated. Based on this, the pattern may be star and grid, or star and circular Road pattern-star and circular type Road pattern-star and grid type 3. Hexagonal Pattern  The basic figure of the road network in this case is a hexagon; each hexagon has at least one side common with an adjacent pattern, as shown in Figure below  The hexagonal pattern can be modified by dividing the hexagon into six triangle units by link roads; this facilitates travel from one place to any other place in the area in the minimum possible time, compared to any other pattern. This, in fact, is known as a ‘minimum travel pattern’ and was used in certain cities to great advantage Road pattern-hexagonal type