San Diego may need to spend billions on roads, water and sewer lines and other infrastructure, but its future economic health depends on local companies marketing their expertise internationally.

That was the message at the Urban Land Institute local chapter's monthly breakfast Tuesday, when a panel explored the issue of infrastructure needed to propel the future economy.

"I don't think our physical infrastructure is the limiting factor," said county Supervisor Ron Roberts. "It's getting more companies to understand how to do it -- where the markets might be -- and get them to have an international look."

Steven Weathers, president and CEO of San Diego's World Trade Center, said local companies should realize that professional services are every bit as important to global trade as manufacturing products.

"Other countries are wanting that expertise to come in," he said, for such things as water treatment plants.

Besides, said Ann Moore, chairwoman of the San Diego Unified Port District board, San Diego's geography around the bay constrains any major expansion of port facilities.

"Shanghai is a huge port," she said of the giant Chinese city. "That's not what we do. We're never going to be that large cargo and container port when you think of Shanghai or Los Angeles."

She said the port is investing in improved shore power for docked ships and hopes to install new cranes and upgrade connections between the waterfront, freeways and rail lines.

Weathers said improved telecommunications, water and sewer systems and other basic systems will also be needed to sustain San Diego's future economy.

"We're also going to be need to have improvements on the education side," he added. "It all goes hand in hand. You can create all the buildings and facilities and if you don't have the right people, it doesn't work."

The conversation took place in the wake of last month's "Report Card for America's Infrastructure," published every four years by the American Society of Civil Engineers.

For 11 categories alone, the society estimated the U.S. needs $3.6 trillion in investment with $2 trillion covered by existing funding sources and $1.6 trillion still required. The group graded the state of U.S. infrastructure as a "D+," up from a "D" in 2009.

San Diego's local chapter, which issued a similar report card last year, did not estimate the costs ahead but concluded that the local infrastructure is in better shape than in the nation as a whole. It gave the region a "C."