Speed and driver impairment from alcohol or drugs are the leading causes of fatal automobile crashes on the Southern State Parkway in Nassau County, Long Island's busiest stretch of road, state and county records show.
Police said speed was a factor in the two most recent multiple-fatality car wrecks on the parkway. A crash on Oct. 8 killed four teens and one on Sunday left two dead and three survivors still in critical condition. The driver in the October crash also was under the influence of marijuana, prosecutors said.
Figures supplied by the New York State Department of Transportation show that from 2007 through 2011, speeding was the primary cause of 18 of the 29 fatal crashes on the Nassau stretch of the Southern State. Those wrecks killed 34 people.
State police, who patrol the parkways, said speeding and driver impairment remain a problem.
"Over the past two years, a significant percentage -- if not almost all -- of the fatalities on this area of the Southern State Parkway have been due to excessive speed and/or operator impairment," said Maj. Patrick Regan, State Police troop commander on Long Island.
Sunday's accident, in which a speeding car slammed into a tree "highlights the unforgiving nature of the Southern State Parkway when the rules of the road are not adhered to," Regan said.
Sixteen people died in 11 crashes on the stretch of parkway in 2011 and 2012, according to records from the Nassau County Traffic Safety Special Traffic Options Program for Driving While Intoxicated, known as STOP-DWI.
Six of those wrecks, which killed 11 people, involved driver impairment, records show. Three of the drivers had alcohol and drugs in their systems when they crashed, two were under the influence of alcohol only and one under the influence of drugs. Three of those crashes also involved unsafe speed, state police said.
Chris Mistron, Nassau traffic safety and STOP-DWI coordinator, said despite efforts to educate the public about the dangers of drug and alcohol impairment, the county averages about 30 drunken driving-related fatalities each year on all roads. The average is an improvement from the 1980s, when the county saw about 70 drunken driving-related fatalities a year, Mistron said.
"But one fatality connected to drugs or alcohol is not good enough -- the county will continue efforts to rid our roadways of drunk or drug-impaired driving," he said.
The Southern State in Nassau carries more traffic than any roadway on Long Island, averaging more than 229,000 vehicles each day at Exit 18, its busiest spot -- Eagle Avenue/Hempstead Lake State Park. That's more than anywhere on the Long Island Expressway, which has more lanes and truck traffic.
The Northern State Parkway carries more than 193,000 vehicles on average in its busiest section -- between the LIE and the Meadowbrook Parkway -- but average daily traffic volume elsewhere on that parkway is mostly less than 150,000 vehicles.
Fifteen crashes killed 16 people on the Northern State Parkway in Nassau from 2007 through 2011, state reports show. The number of crashes on the Northern State is half that for the Southern State, but contributing factors were similar. In 60 percent of the fatal crashes, speed was the key contributor, state records show.
Residents whose homes back up to the Southern State have called for additional guide rails to improve safety.
The DOT in April approved a $7 million guide rail replacement project along the Southern and Northern parkways, to start later this year. Sections of the old wooden rail are to be replaced with galvanized steel to meet current engineering standards. New sections of the rail -- measuring up to 30 inches high -- will be added in some areas.
According to state records, vehicles hit guiderails in seven crashes that killed nine people on the Southern State in Nassau in the past five years and one on the Northern State.