HAMPTON ROADS (WVEC) -- Since 2014, there have been three crashes where tractor trailers drover over the guardrails on the Chesapeake Bay Bridge-Tunnel, and into the water below.

The most recent happened last Thursday, when Joseph Chen’s tractor trailer plunged into the water.

Some of these recent incidents have raised concerns about the bridge’s safety, but engineers explain the safety standards are above standard. The guardrails that line all 20 miles of the CBBT are above federal requirements.

“Our rails are actually 40 inches tall, which actually exceeds the standards by eight inches to provide additional safety,” said Mike Crist, Deputy Director of Infrastructure for CBBT.

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The bridge has been up and running for more than 50 years. During that time period, three cars and 11 tractor trailers have gone over the edge.

“We have a very low incident rate. If you look at the overall safety rating for the bridge, our fatality rate is about half of what the national average is for the highway system,” said Crist.

When the bridge was built, the concrete curb was made taller than the standard curb to provide an extra level of protection. When vehicles start to veer off the roadway, it is designed to redirect them back onto the road.

Each month there are close to a handful of collisions on the bridge. In 2016 alone, 25 trucks and cars hit the guardrails. All but one were saved by the rails.

The bridge is also constantly patrolled by both police and maintenance crews on a daily basis.

“We have two to three crews working on the facility to make sure it’s maintained and all the safety features are working properly,” said Crist.