WASHINGTON— As life in cities worldwide becomes more hectic and more expensive, urban designers are resorting to modern technology to help citizens avoid traffic snarls, and shorten the time needed for shopping and other errands. Technology also is used to cut costly waste.

Santander is a port on the Northern Atlantic coast of Spain that spreads along a bay. Parking is easy to find. As one car drives away, an underground sensor registers that a parking space is now free. Four hundred sensors send messages to signs at street intersections, and GPS devices direct drivers to the nearest available parking spaces, reducing traffic congestion. A smartphone app makes the payment easy and eliminates the problem of finding coins to feed the meter.

Most Santander businesses use scannable barcodes in their windows to save their customers time.

"When we are closed, they can find out about our opening hours, our products and where our other shops are. They can also learn about any sales and special offers we have," said Angel Benito, owner of a shoe-store chain.

In Santander, trash is collected only when the bins are full and bus stop signs show exactly when the next bus is coming. The public parks are watered only when the soil gets dry.

All this is made possible by 20,000 sensors installed on buildings, street posts and even buses. They are part of the "smart city" project, launched by the University of Cantabria seven years ago. University researchers like Luis Muñoz regularly meet with locals to discuss how to make their city even smarter.

"They have ideas they propose and sometimes even develop by themselves. Here, we give them the opportunity to see these ideas happen in real life," said Muñoz.

For example, the university helped a woman create an app that outlines the easiest route for walking with a baby stroller. Another provides information to residents about their water consumption and sends an alert to their phone if there is a leak.

The next innovation on Santander's streets will be ecofriendly streetlights that automatically turn down when no one is there.

One challenge to overcome is making all residents aware of the extent of the innovations available to them.

"They need to do more so everyone can know about it all. Me, I wasn't up to speed at all. Older people don't even know about," said Marina Garcia, a student.

"My son, yes, he knows about it. He is young and handles all those technologies much better than I," added Olga Alzata, a nurse’s aid.

The Santander pilot project is attracting the attention of larger cities in Europe and elsewhere that are looking for smart solutions to urban problems.