JANUARY/FEBRUARY 2018 • FOGHORN 11 FOGHORNFOCUS: SALES & MARKETING bicycles, etc. For a vehicle ferry, it is extremely useful to know when the vehicle deck is full. While this can be deduced from more general data, fluc- tuations in vehicle size (e.g. trucks) make it difficult to know precisely which runs were full. One can plot ridership data in many ways. Each mode of ridership can be plotted over time to show daily, weekly, and seasonal fluctuations. Ratios of ridership modes over time can reveal potential reasons for changes in passenger makeup. Plotting the ratio of passengers to vehicles against the ratio of passenger fares to vehicle fares, for example, may reveal that fare prices incentivized one mode of ridership over another – if passenger fares increase more rapidly than vehicle fares, one might expect to see the ratio of vehicles to passengers increase. Tracking ridership on a per-capita basis can be useful as well, as it elimi- nates population change influences from the ridership data, allowing other influences to be more readily identifi- able. Ticket prices can be plotted over time using net present value to adjust for inflation. Ticket price trends look significantly different when fares are plotted at present value, as shown in Figure 3. Lessons Learned Glosten’s ridership data analysis for Skagit County provided strong evidence that the Guemes Island Ferry’s ridership was influenced by both fares and parking. The notion that fare prices and parking availability at terminals affect ridership will come as no surprise to some operators, but analysis of ridership data can provide statistically significant evidence in support of such assumptions. Having this data on hand may change how operators forecast revenue, or allow them to make more informed tradeoffs – when choosing between adding parking stalls and providing additional service, for example. Analyzing existing ridership data can also help work out which questions your data is not answering, allowing you to reformulate your questions or begin gathering different kinds of data. It is certainly not possible to foresee every event or variable that will affect future ridership. However, tracking the right data with the right methods can help you test assump- tions about past ridership trends and make more informed decisions about your operations, ultimately increasing your profitability. n About the Author William L. Moon III, PE is a Senior Naval Architect at Seattle-based Glosten Associates and an active PVA member. He has over 15 years of experience in passenger vessel design, construction, and refit projects. He is presenting at the PVA Annual Convention at MariTrends 2018 in Savannah, GA.