NEW YORK - One of the nation's oldest suspension bridges is getting a modern makeover: The famous necklace lights on the Brooklyn Bridge will be replaced with energy-efficient bulbs, city officials said Wednesday.

The project is one of several environmental upgrades that Mayor Michael Bloomberg said would soon begin on city facilities. Others include replacing 25,000 street lights and phasing in new hybrid police and fire vehicles. Changing 160 lights on the landmark bridge, which turns 125 years old next year, is expected to cost $500,000 and result in a savings of 24 tons of greenhouse gases annually. Officials said other city bridges that are adorned with lights could follow.

The city's bridges first got their lights in the early 1970s and can be seen from more than 25 miles away.

Bloomberg said the switch - from 100-watt mercury vapor lamps to 24-watt bulbs known as light-emitting diodes - would not be noticeably dimmer.

Light-emitting diodes, or LEDs, typically last three times longer, said Jonathan Wish, chief strategic officer at LED Dynamics, which is not affiliated with the city's project. Most mercury vapor lights endure for 24,000 hours, or about 1,000 days, before burning out, he said.

“Because of the longevity, they're not going to have to change these lights for years, and that will save maintenance costs on top of electricity,” he said.

The city said a special prototype is being developed; the lights are expected to be replaced next year.

Last spring, Bloomberg's administration released a report that found the city's carbon count was 58.3 million metric tons of greenhouse gases in 2005. That accounts for nearly 1 percent of all emissions nationwide; the U.S. total was 7.26 billion metric tons that year.

The mayor wants to achieve a 30 percent reduction in greenhouse gases citywide by 2030, but the projects outlined Wednesday are part of a short-term plan to see immediate, and more modest, reductions on the way to that larger goal.

In total, the short-term projects are estimated to achieve a greenhouse gas reduction of 34,000 tons a year.

Those efforts include buying 20 GMC Yukon Hybrid sport utility vehicles for the police and fire departments to use in emergency responses.

The new two-mode gas-electric transmission systems use a computer to choose from thousands of combinations of running on one electric motor, two electric motors, a combination of electric motors and the gasoline engine or shutting down some of the gas engine's cylinders.

Deputy Mayor Ed Skyler said the Yukon is the first hybrid with enough horsepower for police and fire emergency use.

Also for the first time, the city will pilot three new hybrid garbage trucks.

In New York, transportation doesn't account for as much of the total emissions count as pollutants from buildings. In the highly dense urban environment, building operations and the electricity, natural gas, fuel oil and steam that they consume make up 79 percent of the total, the city report found.

The city's short-term plans for greening building operations include replacing interior lighting in some schools, police precincts, sanitation garages, firehouses and other municipal office buildings.