Over the past several months, the company has seen an increase in freight moving through its Riverside warehouse and hub, according to president and chief executive officer Jack Hawn. The 16 trucks are 2015 Freightliner Cascadia day cabs, equipped with automatic transmissions. They comply with the most recent diesel-truck emission regulations of the California Environmental Protection Agency’s Air Resources Board. The increase is Zenith’s fourth addition to the fleet in as many years. The company’s long-range strategic plan includes the opening and expansion of regional hubs throughout the U.S. Zenith operates more than 3.5 million square feet of warehousing across the country.