Philippine Standards for Geometric Highway Design PDF

**Philippine Standards for Geometric Highway Design** The design of highways in the Philippines is governed by the Department of Public Works and Highways (DPWH), which sets standards to ensure the safety, functionality, and durability of road infrastructures. These standards cover various aspects...

**Philippine Standards for Geometric Highway Design** The design of highways in the Philippines is governed by the Department of Public Works and Highways (DPWH), which sets standards to ensure the safety, functionality, and durability of road infrastructures. These standards cover various aspects of highway design, from lane and shoulder width to pavement thickness and material requirements. Adherence to these guidelines is essential for constructing roads that can withstand the country's growing traffic demands while ensuring the safety of both drivers and pedestrians. **Lane Standards** 1. Expressways: According to the DPWH, the typical lane width for expressways is 3.65 meters (12 feet). All vehicle kinds, including big trucks, buses, and individual automobiles, can travel safely on this width. Large cars may travel at high speeds on expressways with ample room to maneuver due to the 3.65-meter lane. In addition, the number of Lanes depends on capacity needs and traffic demand estimates, expressways frequently include numerous lanes---at least two or three lanes in each direction. These lanes are intended to handle heavy traffic loads during peak hours and provide a smoother flow. 2. Rural Highways: In rural highways, the lane width typically ranges from 3.0 to 3.3 meters (approximately 10 to 11 feet) same goes in urban areas, asphalt or concrete pavements used based on traffic load and regional conditions. These lanes are narrow compared to expressways due to lower traffic volumes. Since, rural highways usually experience lighter traffic, so the narrow lane width is appropriate for roads with fewer lanes and lower-speed vehicles. **Shoulder Standards** On expressways, shoulder widths typically measure 2.5 to 3.0 meters. This wide shoulder serves multiple functions: it provides a space for emergency vehicles or break-down cars, offers room for cyclists or pedestrians in some cases, and acts as a buffer zone between moving traffic and obstacles or barriers on the side of the road. While in rural areas, shoulders are often narrower, ranging from 1.5 to 2.5 meters. The same goes with urban areas, the primary function of the shoulder in rural areas is to provide a safe space for stopping in emergencies for slow-moving agricultural vehicles, which is common in rural settings. **Sidewalk Standards** The DPWH mandates that sidewalks in urban settings have a minimum width of 1.2 meters. In high-density areas with substantial pedestrian traffic, the width can be increased to 2.5 meters or more to accommodate the foot traffic safely. On the other hand, Sidewalks must be accessible to persons with disabilities (PWDs), as per the Batas Pambansa Blg. 344, also known as the Accessibility Law. This includes providing curb ramps at pedestrian crossings, tactile paving for the visually impaired, and ensuring that sidewalks are free from obstructions. Sidewalks are typically made of concrete for durability, with some areas featuring brick or other paving materials for aesthetic purposes. Sidewalks must be constructed to be level and smooth, with proper drainage to prevent water pooling. **Carriageway Standards** The width of the carriageway, which consists of all lanes intended for motorized traffic, is determined by the kind of road and where it is located. Wider carriageways can accommodate additional lanes for heavier traffic loads. In metropolitan settings, carriageway widths typically range from 6.70 to 12 meters. A highway width of seven meters is typical in rural areas with less traffic, giving two cars enough room to pass safely. To guarantee efficient traffic movement and lower the likelihood of accidents, proper carriageway dimensions are essential. **Concrete Thickness Standards** A highway\'s lifetime and functionality are greatly impacted by the thickness of its concrete pavement, particularly in regions where large vehicle loads are present. The DPWH requires that concrete for primary roads and highways, including national highways that link large cities, must have a thickness of between 280 and 300 millimeters (11 to 12 inches) and steel dowels in all transverse joints. This standard takes into consideration the considerable traffic volume that commonly travels these highways, including buses and trucks. Because of the thicker concrete, the weight of these cars is distributed more uniformly, reducing the likelihood of early road failure like cracking or rutting. On the other hand, the concrete thickness for secondary roads which sometimes see less traffic can be lowered to 150--200 millimeters (6--8 inches). These roads might have a thinner layer of concrete because they are not as heavily used by large vehicles. To stop cracking and increase the pavement\'s lifespan, appropriate reinforcement with steel bars or mesh is still required, especially in places that experience frequent temperature changes or severe rainfall. **Subbase Material Standard** In road construction, the subbase, which lies between the base course and the natural ground, is an essential layer. It is essential for spreading weight off the road surface and enhancing drainage. Although this can vary depending on the estimated traffic load and the kind of soil beneath the road, the DPWH specifies that the subbase must be at least 150 millimeters (6 inches) deep. Granular materials, such as sand, gravel, or crushed stone, are usually used to make the subbase and have to adhere to strict quality criteria. The material used for the subbase must have a California Bearing Ratio (CBR) of at least 2% for it to function as intended. The CBR test is used to evaluate a material\'s strength and capacity to withstand loads from vehicles. A 20% CBR guarantees that the subbase can bear the weight of the traffic and the pavement without failing or deforming excessively. **Base course Material Standards** The base course, which forms the basis for the road surface, is the layer just underneath the concrete pavement. It serves as a solid substance for the layers of asphalt or concrete by distributing the traffic load across the subbase. Although this can be increased in locations with high traffic or weak subgrade conditions, the DPWH stipulates that the base course must be at least 150 millimeters thick to prevent deformation or failure. Crushed rock or aggregate are commonly utilized as base course materials. These materials need to be strong and resilient enough to handle traffic-related pressures. The base course material\'s California Bearing Ratio (CBR), which measures its strength in supporting large loads, should be at least 80%. A high CBR number indicates that the base course will not deform, guaranteeing that the pavement above is stable and useful for an extended amount of time. In conclusion, the Philippine Standards for Geometric Highway Design ensure that, while taking into consideration variations in traffic volume, vehicle types, and road conditions, highways are constructed to satisfy the requirements of both urban and rural settings. To guarantee the safety, durability, and functionality of the road network, standards for lane widths, shoulder measurements, sidewalk accessibility, concrete thickness, and subbase and base course materials are all meticulously calibrated. The Philippines can build and maintain roads that promote economic growth and offer everyone safe, effective transportation by following these rules. **REFERENCES** 1. **Department of Public Works and Highway (DPWH) Standards.** (n.d.). Specification for National Roads and Highways. 2. **Department of Public Works and Highway (DPWH).** Design Guidelines, Criteria, and Standards, 2015 Edition. Retrieved from 3. **Department of Public Works and Highway (DPWH).** Minimum Pavement Thickness and width of National Roads. [Department of Public Works and Highway (DPWH)](#:~:text=For%20new%20road%20construction%2C%20rehabilitation,than%207.0%20x%2010%206.)