To cross a two-lane roadway at 30 mph, what is the approximate gap required?

To cross a two-lane roadway at a speed of 30 mph, an approximate gap of 1/2 block is necessary for safety. This calculation takes into account several factors, including the time it takes for a vehicle traveling at that speed to cover the distance of the roadway and the time it would take for a pedestrian or smaller vehicle to cross safely.

At 30 mph, a vehicle travels approximately 44 feet per second. Therefore, to estimate the gap needed for safe crossing, we consider the length of the roadway, which represents the distance between vehicles. A gap of about 1/2 block provides adequate time for the crossing because it allows the crossing entity to gauge the distance and speed of oncoming traffic. This ensures that there is sufficient time not just to enter the roadway, but also to safely complete the crossing without the risk of being hit.

Choosing a gap that is shorter, such as 1/4 block, might not provide enough margin for safety, especially if the approaching vehicle is closer than anticipated. A full block, while appearing safe, could be overly cautious and is not necessary when crossing at a moderate speed like 30 mph, as it may lead to waiting longer than required. The concept of a "full lane