How wide is the subgrade of a bidirectional eight-lane road?

[VanLeilani]

Bidirectional eight-lane road subgrade is 2x15 wide. Components of a highway: The highway surface mainly includes several major parts such as the main road, ramps, and auxiliary lanes. The main road is the carriageway, which is divided from left to right into overtaking lanes, fast lanes, and slow lanes (travel lanes) according to different quantities. Ramps come in complex and diverse forms, including functional ramps, acceleration lanes, deceleration lanes, collector-distributor lanes, and turning ramps, depending on their specific functions. Types of highways: Depending on the scale of the road, highways are divided into three types: bidirectional four-lane, bidirectional six-lane, and bidirectional eight-lane.

[SanLyla]

I've been driving for over a decade. The typical width of a bidirectional eight-lane roadbed ranges from 35 to 40 meters. Each lane is approximately 3.5 meters wide, totaling 28 meters for all eight lanes. The central divider is about 2 meters wide, serving to prevent head-on collisions. The shoulders on each side measure 2 to 3 meters, potentially bringing the total width to over 35 meters. Urban expressways are designed more compactly, around 30 meters wide, while highways are wider, reaching up to 40 meters. Driving on such roads feels quite spacious, reducing the risk of traffic jams and making driving more relaxed. The wider road provides better visibility and more space to handle emergencies. Overall, the roadbed width is determined by traffic volume, significantly reducing congestion during peak hours.

[TimothyRose]

I'm an experienced driver. The subgrade width of a dual eight-lane road generally fluctuates around 35 meters. Each lane is 3.5 meters wide, totaling 28 meters for eight lanes. The central median is typically 2 meters wide, which is particularly effective in preventing accidents. The shoulder width is about 2.5 meters, bringing the total width close to 35 meters. Urban road designs may reduce it to 33 meters due to space constraints, while highways are wider, reaching 38 meters or more. Wider roads make driving smoother, with less congestion during lane changes and a greater sense of safety in rainy conditions. Having driven in many cities, I find that wider roads improve traffic efficiency and prevent congestion. The key lies in design standards—too narrow and accidents are more likely; too wide and land resources are wasted.

[AmeliaFitz]

I prioritize driving safety, and a two-way eight-lane roadbed is approximately 35 meters wide. Each standard lane is 3.5 meters wide, totaling 28 meters for eight lanes. The 2-meter-wide central divider is crucial to prevent head-on collisions. The shoulders on each side are 2 to 3 meters wide, bringing the total width close to 35 meters. A wider roadbed allows for greater spacing between vehicles, reducing the risk of rear-end collisions, especially at night or in foggy conditions. In urban areas, roads might be designed 30 meters wide, but highways are even wider at around 40 meters. Driving is much more comfortable, without the frequent hard braking required on narrow roads. Road width impacts accident rates—wider roads provide more buffer space, a core element of safety design.