INTERNATIONAL tariffs and amendments to trade policy may have an adverse effect on some US ports, warns bond rating firm Fitch, pointing to gateways that rely on the steel and aluminium trade being likely to be hit first. "Demand for infrastructure investment remains strong. Infrastructure as an asset class remains resilient but is not free from risk," American Shipper cited a Fitch report as saying. "In the transportation space, Fitch Ratings' median rating between 2007 and 2017, which included the effects of the global financial crisis and the subsequent recovery, remained largely stable, with airports and seaports remaining at 'A' and toll road projects moving up a notch to 'BBB+.'" Fitch expects port cargo traffic growth to keep pace with an expanding US economy, however, it also highlights a number of longer-term trends that could affect ports in the future. It said tensions over trade have not sparked any immediate changes in bond ratings and while shippers may be moving cargo ahead of specific tariffs or lowering risk by downsizing inventories, "reducing production levels and delaying purchases or sales may also have an effect in the near term but changes are expected to be marginal for now." The risk of competition to primary ports in major metropolitan areas is regarded by Fitch as moderate, as "the more monopolistic or efficient the related infrastructure is, the greater its credit strength." It made an example of the Alameda Corridor Transportation Authority that serves the ports of Los Angeles and Long Beach, which it believes "has tremendous strength. The two main railway operators serving the port, Union Pacific and BNSF, share the same line and cover almost all of the operating costs. "There is competition from trucks but this is largely limited to the two-thirds of cargo that stays in the LA metro area; for longer distance deliveries, the higher cost of trucking gives rail an advantage." It said: "The same may be true to a lesser extent for terminals and storage yards, as they will have relative strengths and weaknesses depending on location relative to the greater port complex and the markets they serve; the relative quality of their supporting infrastructure; and ease of ingress/egress. Their levels of demand and pricing will vary accordingly. "As observed during periods of stress, such as various labour disputes on the west coast and through the global financial crisis nationwide, most ports can absorb volatility of up to 10 per cent in their volumes for a short period of time," concluded Fitch.