Office of Naval Research - National Transportation Library

natural gas as a viable fuel choice for marine propulsion because it was cheaper than marinediesel fuel, the price of which at some point spiked at over $4 per gallon. However, the priceadvantage has disappeared, at least for the time being; it should be noted that the natural gasmarket is also subject to volatility and that the relative cost advantage may shift back andforth between these two fuels over time.While some past investigations of natural gas propulsion have identified design, safety, andoperational barriers, there are nonetheless many ferries now fueled by natural gas, stored incompressed form. One example of a ferry operating on compressed natural gas (CNG) is theM.V. Virginia, built by Tidewater Regional Transient Ferry, powered by a CNG system witha Caterpillar 300-hp. spark ignited engine. 64The U.S. EPA now addresses emissions from marine engines as “non-road” or “off-road”diesel engines through regulation of both fuel content and emission limits. In May 2004,EPA finalized new requirements for non-road diesel fuel that took effect in 2007, to decreasethe allowable levels of sulfur in fuel used in marine vessels by 99 percent. These fuelimprovements are likely to increase the expected environmental and public health benefitsdue to particulate matter reductions from new and existing engines. 65Avoided Noise CostsBased on the rates estimated by the FHWA cost model from the Highway PerformanceMonitoring System (HPMS) database, the noise costs per truck trip in urban and ruralsectors are estimated at the mid range (from a range of 4.5 cents to 0.48 cents per mile)amounting to $5.64 for the New York-Boston transit.Avoided External Costs of Infrastructure Repair Not Paid for by UserFeesThe user fees paid by heavy trucks do not fully cover the additional of pavement repair.Based on the FHWA Highway Cost Allocation Studies (HCAS), the infrastructure costs permile depend on the vehicle type/size and the class of highway segment travelled (urbanversus rural.) HCAS estimates indicate that repair and maintenance costs for urbansegments are 3 to 4 times higher than rural segments, because of the more elaborate natureof the urban highway structures and greater disruption and traffic delays generated. Theestimated unpaid-for infrastructure-repair costs per one-way truck trip from Boston to NewYork are 20.52 cents. The user fees paid by 5-Axle Combination trucks traveling on urbaninterstates for diesel fuel taxes, vehicle excise taxes, tire taxes, and the Heavy Vehicle UserTax (HVUT) for pavement repair add up to 7.4 cents per mile. The total Federal costs forrepair and maintenance of the urban highway segments amount to 21.1 cents per mile. Thedifference between what the heavy truck users of the urban infrastructure segments pay andthe federal costs represents a public burden of 13.8 cents per mile. The differential isequivalent to a public subsidy of 13.8 cents per mile to the trucking sector for the Boston-New York shipment.64 Brett and Wolff, LLC website, http://www.brettandwolffllc.com/ngmvessels.html.65 Ibid.ONR SSS Final Report 60