This is Robert Cohen with the VOA Special English DevelopmentReport.

Each year, road accidents kill a million people and injuremillions more. The economic costs are greatest for developingcountries. Earlier this year, the United Nations called for acampaign to improve road safety.

One way to avoid accidents isbetter driving. Another is better roads and bridges. Engineers inthe United States have designed ten new concrete mixtures that theythink could make bridges last longer.

Professor Paul Tikalsky leads the experiments by a team atPennsylvania State University. He says bridges made of concrete nowlast about twenty-five to thirty-five years. But he says the newmixtures might extend that to seventy-five or even one-hundredyears.

Concrete is made of stone, sand, water and cement. The materialsin the cement hold the concrete together. Ancient Romans built withconcrete. Yet strengthened concrete bridges did not appear until thelate eighteen-hundreds. People keep looking for new ways to improveconcrete. Professor Tikalsky says it is one of the most complex ofall chemical systems.

The new mixtures designed by his team contain industrial wasteproducts. He says these make the concrete better able to resistdamage from water and salt over time. One of the products is flyash. This is released into the air as pollution when coal is burned.

Professor Tikalsky says particles of fly ash are almost exactlythe same size and chemical structure as Portland cement. This is themost costly material in concrete. So using fly ash to replace someof it would save money.

Over the next two years, engineers will study ten bridges inPennsylvania. These were built from the different cement mixturesdesigned by Professor Tikalsky's team. He says longer-lastingbridges could save the state more than thirty-five-million dollars ayear. And he says the materials would be environmentally friendly.

The federal government is paying for part of the research.Engineers anywhere can use the technology. Professor Tikalsky sayssome of the ideas have already been put to use in China, thePhilippines and other countries.

You can find more about this research on the Pennsylvania StateUniversity Web site. The address is www.psu.edu. Again, the site iswww.psu.edu.

This VOA Special English Development Report was written by JillMoss. This is Robert Cohen.