Rolling Start

A rolling start is a method of beginning or restarting a motorsport race where the cars are already moving at a controlled speed when the official race begins, rather than starting from a complete stop.

In a rolling start, all the race cars line up in their proper positions behind a pace car (also called a safety car). This pace car leads the entire field around the track at a slow, steady speed for one or more laps. During this time, drivers must stay in their assigned positions and cannot pass other cars.

When it's time for the race to officially begin, the pace car exits the track and a green flag is waved or green lights are shown. At this signal, drivers can accelerate to full racing speed, but only after crossing a designated line on the track called the acceleration zone.

Rolling starts are commonly used in NASCAR and IndyCar racing for both the initial race start and when restarting after caution periods. They're also used in other racing series when track conditions are challenging, such as during wet weather, because they're considered safer than having cars accelerate from a complete stop.

The main advantage of a rolling start is that it gets the race going more quickly and smoothly than a standing start. It also helps warm up the tires before full-speed racing begins. However, it can be harder for drivers to gain positions at the start compared to a standing start, where reaction times and launch techniques play a bigger role.

This contrasts with a standing start, which is more common in Formula 1 racing, where cars begin completely stationary on the starting grid and must accelerate from zero when the race begins. Each method creates different strategic opportunities and challenges for drivers and teams.