Merging onto traffic-congested highways can be a potentially dangerous task, especially when taking into account the unpredictability of other drivers’ actions.

However, fleet managers can teach their drivers to merge safely onto busy highways, by driving defensively and take precautions to prevent collisions when merging.

One tip fleet managers can pass along to their drivers might be obvious but is key to being safe: Adjust vehicle speed to match the flow of traffic before entering the highway, and yield to other drivers. Crucially, drivers should avoid stopping unless absolutely necessary, since traffic already on the highway has the right of way. Also, drivers should signal their intentions to other drivers early — at least 100 to 300 feet before merging or changing lanes, according to auto insurer State Farm.

“Unfortunately, many drivers don’t look far enough ahead as they’re driving, so they don’t spot you until the last moment and you could already be merging, assuming the driver has already identified you. So, you want to make sure that you’re visible as much as possible,” said Art Liggio, president of Driving Dynamics.

Drivers should also make sure to have a three- to four-second gap in traffic when merging — and, this gap should be identified as soon as possible. Rather than looking for the vehicle they want to get in front of, drivers should look for the vehicle they want to be behind, Liggio said.

“A lot of the collisions that occur while merging transpire if there’s another vehicle ahead of the driver that’s also trying to merge. Often, both drivers are trying to pay attention to the lane they’re trying to merge into, and the second vehicle is not paying attention to the driver ahead. As a result, when that driver in front makes a sudden change in movement — slowing down or coming to a complete stop — the second vehicle doesn’t have that information because the focus is on the merging highway, and rear-end collisions take place,” Liggio said.

State Farm recommends a number of other tips to drivers for merging onto highways:

• Wait for the solid line to end before merging into traffic. 

• Cross one lane of traffic at a time.

• If the driver must pass a slower-moving vehicle, pass on the left and return to the original lane only after the slower vehicle is visible in the rearview mirror. Increase this distance when passing larger vehicles.

And, Liggio recommended drivers properly adjust all vehicle mirrors, extending side-view mirrors further outward so the driver can see the adjacent lane.

"Because side-view mirrors are tightly focused inward, drivers go through all types of contortions, such as turning their head and moving their shoulders about," said Liggio. "As a result, drivers lose sight of what's ahead of them. If drivers have their mirrors properly adjusted to just slightly see the side of their vehicle, they’ll get a better view of what’s in the lane they wish to merge into."