Drivers in the United States wasted $124 billion by sitting in traffic jams in 2013, according to a study by American and British researchers. The study also warns that this gridlock is likely to persist and worsen in the next 15 years.

The study was a collaboration between the Centre for Economics and Business Research and INRIX Inc. to analyze the annual cost of traffic gridlock in both the United States and Europe. The report concludes that annual congestion costs in the United States will increase almost 50 percent to $186 billion in 2030.

The study says money lost on congestion will also increase in overseas economies as well. By 2030, the cumulative loss in all countries in the study is estimated to reach $4.4 trillion.

"The scale of the problem is enormous, and now we know that gridlock will continue to have serious consequences for national and city economies, businesses, and households in the future," said Kevin Foreman, general manager of INRIX GeoAnalytics. "Improving public transport infrastructure may provide more choice for travelers, but it won't solve the problem. Technology innovations like multi-modal routing and real-time traffic in connected cars and on mobile devices should be adopted more widely, helping to create smarter cities worldwide."

The cost of congestion was calculated using both direct and indirect costs. Direct costs include fuel burned while idling and lost productivity. Indirect costs include higher freight and business fees that can be passed on to the consumer when company vehicles idle in traffic.

Researchers say increased urban populations and higher living standards are the primary trends driving the increasing costs of congestion. They expect that there will be 281 million vehicles on the road in the United States in 2030, an increase of 30 million from 2013. Vehicle miles traveled per year in four countries included in the study are predicted to increase 19 percent, resulting in a six percent decrease in the average speed of traffic during congested periods.

The cumulative effect of increased congestion costs between 2013 and 2030 is projected to be $2.8 trillion in the United States. The study says American households lose an average of $1,700 to congestion costs each year, and that this figure is expected to increase to $2,300 by 2030.

This cost is still the lowest projected increase in the study, with American drivers having the lowest number of hours wasted in traffic jams each year. The highest anticipated increase in congestion costs will be in the United Kingdom, where annual congestion costs per household are forecast at $3,217 for 2030.

In addition to the United States, the study looked at the effect of congestion on the economies of the UK, France, and Germany. The UK has the highest projected congestion costs, anticipated to increase 63 percent from $20.5 billion in 2013 to $33.4 billion in 2030. Both France and Germany are expected to have a 31 percent increase in congestion costs.

The study also looked at the congestion costs in individual metro areas by analyzing the most gridlocked cities in each country: Los Angeles in the United States, London in the UK, Paris in France, and Stuttgart in Germany. The combined congestion costs in these cities are expected to increase 63 percent, from $46.6 billion in 2013 to $75.9 billion in 2030.

Researchers say the largest effect will be in London, with estimated costs increasing by 70 percent to $14.5 billion in 2030. Los Angeles accounted for about 20 percent of the congestion costs of the United States in 2013, and these costs are expected to increase from $23.2 billion in that year to $38.4 billion in 2030.

Paris households are predicted to have the highest increase in annual congestion costs at 51 percent. However, the high number of commuters and vehicles in Los Angeles means that this city has the highest overall cost predicted for 2030: $8,555.

Vehicle miles traveled in the four cities is predicted to increase by 21 percent, resulting in an 11 percent decrease in the average congested speed.

The study says the monetary value of carbon emissions created by vehicles idling in traffic in 2013 was $300 million. This figure is expected to increase to $538 million in 2030, with a cumulative cost of $7.6 billion.

"The key to deterring these cost predictions is developing long-term solutions that enable more efficient usage of our roads," said Foreman. "This means creating greater connectivity among vehicles and engineering smarter cities to support this connectivity."

INRIX says steps that can improve technology include multi-modal navigation services to let people know the fastest mode of transportation to reach their destination; real-time analytics services to communicate with vehicle and smartphone systems to direct a driver along the most efficient roads; and developing an infrastructure to support autonomous vehicle technology allowing cars to travel at the same speed during peak times.

CEBR, based in London, is an independent consulting and research company that focuses on business and economic trends. INRIX provides real-time traffic information and transportation analytics; the company is based in Kirkland, Washington.