Highway Development and Planning PDF

CHAPTER 2 HIGHWAY DEVELOPMENT AND PLANNING HIGHWAY AND RAILROAD ENGINEERING PREPARED BY: ENGR. JOSHUA FERDINAND B. VILLAFUERTE CIVIL/TRANSPORT PLANNER CHAPTER 2 HIGHWAY TYPES / CLASSIFICATION Functional classification groups highways by the characte...

CHAPTER 2 HIGHWAY DEVELOPMENT AND PLANNING HIGHWAY AND RAILROAD ENGINEERING PREPARED BY: ENGR. JOSHUA FERDINAND B. VILLAFUERTE CIVIL/TRANSPORT PLANNER CHAPTER 2 HIGHWAY TYPES / CLASSIFICATION Functional classification groups highways by the character of service they provide, and is primarily based on motor vehicle travel characteristics and the degree of access to adjacent properties. The six recognizable stages in motor vehicle travel include main movement, transition, distribution, collection, access and termination. Each of these stages is handled by a separate facility designed specifically for its function. CHAPTER 2 HIGHWAY TYPES / CLASSIFICATION The traffic characteristic which has the greatest effect on highway design is the volume of traffic. The design element which is the most affected by the volume of traffic is the number of traffic lanes. In modern practice, single-lane and 3-lane highways are considered inappropriate as parts of an improved highway system From the standpoint of engineering design and construction at least 2-traffic lanes should be considered in any proposed highway no matter how low the traffic volume may be. Highway types are therefore considered to be 2-lane, multi- lane (four or more lanes), undivided and multilane divided highways. HIGHWAY TYPES / CLASSIFICATION 2-LANE HIGHWAYS 2-lane highways constitute the majority of the total length of highways, varying from gravel or other loose surface roads to high type pavement. Lane Width or Carraigeway Width = 3.00 m to 3.65 m (Standard: 3.35 m) Factors to consider: traffic volume, design speed, character of terrain and economic consideration Shoulders = 3.00 m wide Note: narrow shoulder widths may be used in rugged terrain where traffic volume is low or when economic considerations govern. HIGHWAY TYPES / CLASSIFICATION 2-LANE HIGHWAYS Climbing Lane (For grade > 6%) = 3.00 m to 3.35 m wide Note: If a hill is too steep and trucks going up make it even harder, it's a good idea to add an extra lane for those climbing trucks. This is especially needed when the number of trucks going up is 20% or more than what the road can normally handle. Design = Lane Width + Climbing Lane + 1.20 m Shoulder With Proper signages + markings The climbing lane should begin near the foot of the grade at a point determined by the speed of the trucks at the approach to the grade. Where practicable, the climbing lane should end at a point beyond the crest where the truck can attain a speed of 50 kph.  HIGHWAY TYPES / CLASSIFICATION UNDIVIDED HIGHWAYS (4 Lanes or More) The narrowest highway on which each traffic lane is intended to be used by traffic in one direction and passing is accomplished on lanes not subject to use by opposing traffic. The ability to pass without travelling in the lane of opposing traffic, results in a smoother operation and a large increase in highway capacity. Speed limit = 60 kph or less Note: they should feature prominent road marking to separate opposing streams. Adequate shoulders which encourage all drivers in emergencies to use them are essential Undivided highways are most applicable in urban and suburban areas where there is concentrated development of adjacent land.  HIGHWAY TYPES / CLASSIFICATION UNDIVIDED HIGHWAYS (4 Lanes or More) Superelevation or banking When a vehicle travels around a curve or on a sloped road, centrifugal force tends to push the vehicle outward. To counteract this force and keep the vehicle on the road, the road is designed with a slightly elevated outer edge compared to the inner edge. Superelevation runoff also known as "cross slope runoff" or "banking runoff," refers to the management of water that accumulates on the surface of a curved roadway or a sloped road during rainy or wet conditions. refers to the design considerations and methods used to ensure that water drains effectively from the road surface, preventing the buildup of water and maintaining safe driving conditions. This involve shaping the road surface, creating channels or gutters to direct water flow, and incorporating drainage systems to handle the runoff efficiently.  HIGHWAY TYPES / CLASSIFICATION DIVIDED HIGHWAYS Divided highways can have varying widths and pavement levels for better design and cost-efficiency. Climbing lanes on multilane roads might be needed if long uphill stretches reduce capacity by 30% or more compared to normal traffic. Designing divided highways with medians affects how superelevation runoff is managed: - The whole road, including the median, can be superelevated as one section. - The median stays flat, and the pavements rotate around it. - Each pavement can be treated differently for runoff, causing varying heights at the median edges.  HIGHWAY TYPES / CLASSIFICATION DIVIDED HIGHWAYS Highways with widely separated roadways have advantages like easy vehicle operation, better drainage, and a nice look. Open views between separated roadways help show that they're meant for one-way traffic on long divided highways. A divided highway has separated roadways for traffic in opposite directions. It usually has two full lanes per direction and a wide median for safety. Divided highways are safer, more comfortable, and good for high-volume, high-speed traffic. Medians 1.20 m to 1.80 m wide are fine in rural areas, but wider medians, ideally 4.50 to 18.50 m, are better for separating traffic and planning intersections. CLASSIFICATION OF HIGHWAYS ACCORDING TO SYSTEM NATIONAL ROADS Public roads, declared as national roads by the President of the Philippines upon recommendation of the Secretary of Public Works and Highways satisfying the conditions set forth under Executive Order No.113, Establishing the Classification of Roads. National roads are divided into primary, secondary, and tertiary roads. Road Right of Way: Minimum of 20.00 meters. Width of Traveled Way for 2-lane roads: Minimum of 6.70 meters. Allowable Grade (slope): 6.0% is the highest allowed. CLASSIFICATION OF HIGHWAYS ACCORDING TO SYSTEM PROVINCIAL ROADS Provincial Roads connect municipalities, with the endpoint usually being a public plaza. They can also extend from a municipality or a provincial/national road to a public wharf or railway station. To receive national aid for maintenance, a provincial road needs to be officially recognized. The Secretary of the DPWH designates it upon the recommendation of the Provincial Board (Sangguniang Panlalawigan). Road Right of Way: Minimum of 15.00 meters. Width of Traveled Way: Minimum of 6.10 meters. Allowable Grade (slope): 6.0% is the highest allowed.  CLASSIFICATION OF HIGHWAYS ACCORDING TO SYSTEM CITY ROADS / MUNICIPAL ROADS City Roads are roads or streets located within the urban area of a city. They are not classified as provincial or national roads. Municipal Roads are roads or streets within the poblacion area of a municipality not classified as provincial or national roads. Road Right of Way: Minimum of 15.00 meters. Width of Traveled Way: Minimum of 6.10 meters. Allowable Grade (slope): 6.0% is the highest allowed. CLASSIFICATION OF HIGHWAYS ACCORDING TO SYSTEM BARANGAY ROADS Barangay Roads are roads found outside the central area of a municipality or the urban part of a city. These roads are also outside industrial, commercial, or residential subdivisions. NOTE: Access roads to subdivisions are not considered barangay roads. These roads work as feeders connecting Farm-to-Market roads and don't fall into the categories of national, provincial, city, or municipal roads. Road Right of Way: Minimum of 10.00 meters Width of Traveled Way: Minimum of 4.00 meters Allowable Grade (slope): Maximum of 10.0% CLASSIFICATION OF HIGHWAYS ACCORDING TO SYSTEM TOURISM ROADS Tourism Roads are roads that are specifically marketed for tourists. They might be existing roads promoted with signs and advertising, or they could be roads built for tourism purposes. Some Tourism Roads are designed to showcase unique natural beauty and might also be enjoyed by local residents. Tourism Roads are built to attract tourists and boost local economies. They can create jobs, improve community infrastructure, and help rural areas. Road Right of Way: Minimum of 15 meters. Width of Traveled Way: Minimum of 6.10 meters. Allowable Grade (slope): 6.0% is the highest allowed. CLASSIFICATION OF HIGHWAYS ACCORDING TO SYSTEM FARM-TO-MARKET ROADS Farm-to-Market Roads are roads that connect places where agricultural and fisheries products are produced, coastal landing points, and post-harvest facilities to markets, major roads, and highways. These roads are vital for transporting agricultural goods from their sources to markets and distribution points. Road Right of Way: Minimum of 6.00 meters. Width of Traveled Way: Minimum of 4.00 meters. Allowable Grade (slope): 10.0% is the highest allowed. ROAD CLASSIFICATION ACCORDING TO PRIMARY FUNCTION EXPRESSWAYS These are divided arterial highways for through traffic, with full or partial control of access and generally with grade separations at major intersections. PARKWAYS Parkways are arterial highways for non-commercial traffic with full or partial control of access, usually located within a park or a ribbon of park-like development.  HIGHWAY ALIGNMENT HIGHWAY ALIGNMENT Highway Alignment | The position or lay out of center line of the highway on the ground is called the alignment. It includes straight path, horizontal deviation, and curves. If improper alignment was executed, disadvantages could be: Increase in construction cost Increase in maintenance cost Increase in vehicle operation cost Increase in accident Once the road is aligned and constructed, it is not easy to change the alignment due to increase in cost of adjoining land and construction of costly structure. REQUIREMENTS OF HIGHWAY ALIGNMENT SHORT | It should be desirable to have a short alignment between two terminal stations. EASY | It should be easy to construct and maintain with minimum problem and easy for the operation of vehicles. SAFE | It should be safe enough for the construction and maintenance from the view point of stability of natural hill slope, embankment, and cut slope. It should also be safe for traffic operation. ECONOMICAL | Total cost including initial cost, maintenance cost, and vehicle operation cost should be minimum. FACTORS CONTROLLING ALIGNMENT OBLIGATORY POINTS Obligatory points through which alignment is to pass (bridge site, intermediate town, mountain pass, etc.) Obligatory points through which alignment should not pass (religious places, costly structure, unsuitable land, etc.) TRAFFIC Origin and destination survey should be carried out in the area and the desire line be drawn showing the trend of traffic flow. New road to be aligned should keep in view the desired lines, traffic flow patterns and future trends. FACTORS CONTROLLING ALIGNMENT GEOMETRIC DESIGN Design factors such as gradient, radius of curve and sight distance also govern the final alignment of the highway. Gradient should be flat and less than the ruling gradient or design gradient. Avoid sudden changes in sight distance, especially near crossings Avoid sharp horizontal curves Avoid road intersection near bend ECONOMY Alignment finalized based on total cost including initial cost, maintenance cost, and vehicle operation cost. OTHER CONSIDERATIONS Surface water and flood level, drainage, environmental, and political ADDITIONAL CARE IN HILL ROADS TOPOGRAPHICAL CONTROL POINTS The alignment, if possible, should avoid passing through marshy and low lying land with poor drainage, flood prone areas, unstable hilly features MATERIALS AND CONSTRUCTIONAL FEATURES Deep cutting should be avoided Earthwork is to be balanced (quantities for filling and excavation) Alignment should preferably be through better soil area to minimize pavement thickness Location may be near sources of embankment and pavement materials ADDITIONAL CARE IN HILL ROADS STABILITY A common problem in hilly roads is land sliding The cutting and filling of the earth to construct the roads on hilly sides causes steepening of existing slope and affect its stability DRAINAGE Avoid the cross drainage structure The number of cross drainage structure should be minimum GEOMETRIC STANDARD OF HILLY ROAD Gradient, curve, and speed Sight distance, radius of curve GEOMETRIC STANDARD OF HILLY ROAD Total work to be done to move loads along the route taking horizontal length, actual difference in level between two stations, and the sum of the ineffective rise and fall in excess of floating gradient should kept as low as possible. SAMPLE OBLIGATORY POINTS By indicating obligatory points, there will be specific attention given to their design, especially for minor roads and waterways. BIBLIOGRAPHY Hoel, L. A., Garber, N. J., & Sadek, A. W. (2008). Transportation Infrastructure Engineering: A Multi-Modal Integration. Khanna, S. K., Justo C. E. G., & Veeraragavan A. (2014). Highway Engineering. Nem Chand & Bros. Department of Public Works and Highways Bureau of Design (2015). Design Guidelines, Criteria and Standards – Volume 4.