Study: What Causes Accidents on the TZ Bridge?

It may not be what Rockland residents or seasoned commuters would guess, but it's true: the majority of accidents on the Tappan Zee Bridge occur during clear, and not foul, weather.

Drivers now have access to data regarding car collisions and mishaps on the Tappan Zee Bridge, per the (FEIS).

The FEIS, thousands of pages in length, details a wealth of topics relating to the current span and the construction of a new Hudson corssing. In the chapter "Transportation," state officials outline car accident data tracked over the past several years.

According to the report, the Hudson span has two major "accident clusters," or areas on the crossing where collisions are most common. Those areas are between mileposts 13.7 and 14.2 on the west-bound side, and between mileposts 14.2 and 13.8 on the east-bound side.

"In the west-bound [cluster], the accident rate ranges from 2.8 to 3.7 times the national average," the study reads. "In the east-bound direction, the accident rate is greater than 5.2 times the statewide average."

The study notes these clusters are near segments where visibility is limited.

"This results in weaving movements [of cars passing one another] that create a greater potential for conflicts and an increase in accidents," the study notes.

The state document unpacks accident information between the years of 2008 and 2010, citing a total of 1,248 incidents. About 63-percent of those accidents occurred in the east-bound direction, or the lanes going from Rockland to Westchester.

"The steep grade on the bridge, sun glare and weaving maneuvers appear to be the cause of the higher rate for east-bound vehicles," officials write.

Only a handful of the 1,000-plus accidents entail injuries or deaths, according to statistics. About 80-percent of accidents only resulted in "property damage," meaning an automobile sustained over $1,000 worth of breakage.

Other statistics note most of the accidents occurred during clear weather and during daylight hours. Only a handful of the accidents occurred during rain, fog or snow.

The chapter also tackles man-made causes for accidents. Rear-ending is most common, followed by unsafe lane changing and then, in third, debris in the roadway.