[Perencanaan Geometrik Jalan]: Materi pengantar

Summary

This lecture on road geometric planning introduces various essential topics, starting with the classification of roads based on function, load-bearing capacity, and terrain. The course covers aspects of road design such as cross-sections, lane widths, shoulder functions, and the importance of elements like median strips and sidewalks. Key concepts also include the relationship between vehicle speed and road design, as well as the factors influencing shoulder and sidewalk dimensions. The lecture concludes by outlining the various road components and their respective functions, helping students understand how to design roads efficiently and safely.

Takeaways

• 😀 The course is about road geometric planning, which will cover topics such as alignment, road types, and various parameters over the next semester.
• 😀 Roads can be classified based on function into arterials, collectors, and locals, with different speed and distance characteristics for each.
• 😀 Roads are also categorized by their load-bearing class, ranging from Class 1 (heavier loads) to Class 3 (lighter loads), which depends on the permitted axle load.
• 😀 Roads can be categorized based on terrain into flat, hilly, or mountainous regions, affecting road design and planning.
• 😀 Road types can be distinguished by jurisdiction, including national, provincial, district, or special-purpose roads.
• 😀 A cross-section of a road typically includes lanes, shoulders, drainage channels, and safety barriers, which all contribute to road functionality and safety.
• 😀 Medians are central areas that separate traffic lanes and provide safety, comfort, and aesthetics to the road design.
• 😀 Traffic lanes are designed based on the intended speed of vehicles, with wider lanes for faster speeds and narrower ones for slower speeds.
• 😀 Shoulders are important for emergency stopping, vehicle breakdowns, and road maintenance, and their width depends on factors like traffic volume and road function.
• 😀 The width of sidewalks (or pedestrian paths) varies based on pedestrian volume and road usage, ensuring safe walking areas alongside roads.

Q & A

What are the three main classifications of roads based on their function?

The three main classifications of roads based on their function are: Arterial roads, Collector roads, and Local roads. Arterial roads are for long-distance travel with high-speed vehicles, Collector roads are for medium-speed vehicles, and Local roads are for short-distance travel with low-speed vehicles.

How are roads classified based on their load-bearing capacity?

Roads are classified into classes based on the maximum load they can bear. For example, Arterial Class 1 roads can support loads greater than 10 tons, while Class 2 roads can support up to 10 tons. The classification also depends on the size of vehicles using the road.

What is the difference between 'jalur' and 'lajur' in road design?

'Jalur' refers to the entire traffic lane, while 'lajur' refers to a specific lane within that larger traffic lane. The 'lajur' is designed to accommodate the expected vehicle traffic in the 'jalur'.

What is the purpose of the shoulder of the road (bahu jalan)?

The shoulder (bahu jalan) serves multiple purposes, such as providing space for vehicles to stop temporarily, offering a safe area during emergencies, aiding in road maintenance, and facilitating the movement of emergency vehicles.

What factors influence the width of the road shoulder?

The width of the road shoulder is influenced by factors such as the road's function, traffic volume, surrounding activities (e.g., urban or rural), the presence of sidewalks (trotoar), and the available budget for construction.

What is the role of a road's 'median'?

The median serves as a neutral zone that separates two opposing lanes of traffic, enhancing safety by reducing head-on collisions. It also contributes to the aesthetic and functional design of the road and provides space for utilities such as street lighting.

How does the road's slope contribute to its design?

Roads are typically sloped to help drain rainwater into drainage systems. The slope of the road's surface (usually 2-3% for traffic lanes and 3-5% for shoulders) ensures that water doesn't accumulate, which could damage the road surface.

What is the definition of a 'trotoar' and how is its width determined?

A 'trotoar' is a pedestrian walkway adjacent to the road, designed for foot traffic. Its width varies depending on the volume of pedestrians and vehicular traffic in the area, generally ranging from 1.5 meters to 3 meters.

What is the significance of the 'karet' in road design?

The 'karet' is used to clearly define the edge of the road, ensuring that there is a distinct boundary between the road and adjacent areas. This helps in guiding traffic and preventing vehicles from veering off the road.

What is the purpose of classifying roads based on their terrain?

Classifying roads by terrain—flat, hilly, and mountainous—helps determine the appropriate design and construction methods, considering factors like road stability, drainage, and construction costs.