# Benefits of Advanced Air Mobility for Society and Environment: A Case Study of Ohio
## 4 Benefit Factors
### BF-1: Travel Time Savings for Passengers  
This section examines the value of travel time, and travel time savings resulting from AAM passenger transportation using eVTOLs. Travel time is one of the most significant transportation costs, and travel time savings are often the primary justification for transportation infrastructure improvements [36]. Various studies have developed estimates of travel time values for different user types and travel conditions. The Department of Transportation (DOT) and other government agencies always take initiatives that are intended to lower the travel time of the passengers. _Value of Travel Time Savings (VTTS)_ refers to the amount of money that travelers are willing to pay to reduce the travel time. In US DOT's last revised version of departmental guidance for value of travel time in economic analysis, the recommended VTTSs for local and intercity travel on surface mode (except high speed rails) were $14.1 and $20.4 per person-hour in 2015, respectively [37]. For our analysis, we considered the average of the two values ($17.25 per person-hour) as _VTTS_.  
To estimate yearly _VTTS_ for the forecast period, the factors on which _VTTS_ depends were taken into account. According to the US DOT report, the valuation of travel time indicated that _VTTS_ depends on the demographic characteristics of the traveling population (age, sex, hourly median income, personal interest, etc.), location (local or intercity), and the mode (surface, high-speed rails or air) and purpose of travel (personal or business). US DOT considered a set of weighted values for giving different priorities to different purposes of travel, which were derived from the 2001 National Household Travel Survey (NHTS). Considering surface modes, for local travel, the weighted values were 4.6% for business travel and 95.4% for personal travel; for intercity travel, the weighted values were 21.4% for business travel and 78.6% for personal travel. These same values were used in all the previous reports of DOT. Following their reports, it can be assumed based on the same city or state that all the variants mentioned above, except hourly median income, will remain more or less unchanged every year if there is no unusual situation. Using Equation (1), we estimated the _VTTS'_ which refers to the change in _VTTS_ for the next 11 years relative to the year 2015 because $17.25 was formulated based on the year 2015. For estimating the _VTTS'_, we used 31 years of historical data of yearly Median Household Income (_MHI_) of Six Major Cities in Ohio (SMCO) to forecast _MHI_ for the next 11 years based on the process described in Section 3. Then, the forecasted values were placed in a column vector, _MHI_, with 11 \(\times\) 1 order. In this paper, all the bolded variables are the column vectors having 11 \(\times\) 1 order, whereas the non-bolded variables are regular variables. In Equation (1), \(i\) denotes the year index, \(VTTS_{i}\) the _VTTS_ for year \(i\) and \(MHI_{i}\) the _MHI_ for year \(i\):  
\[VTTS_{i}^{\prime}=\frac{MHI_{i}}{MHI_{2015}}\times VTTS_{2015};\qquad i\in\{2022,2023,...,n(year)\} \tag{1}\]According to several studies, travel time-saving is significant if passengers travel by air using AAM for inter-regional trips, for example, city center to city center, or city center to rural proximity, rather than short inter-city trips [31]. The Crown team considered the travel trip-distance between the cities for regularly scheduled or on-demand transportation to be over 50-75 m. We assumed the average distance of a trip (\(d_{1}\)) to be 50 m for our analysis. The difference between eVTOL flight and ground vehicle commute times was determined using ArcGIS real-time traffic data in [31]. A 50 m trip by eVTOL is estimated to take 30 min, whereas a ground vehicle takes 80 min long for the same trip. Thus, the trip-time saving (\(s\)) is 50 min for each passenger in each trip using eVTOL. If \(d_{1}\) is considered more than 50 m, \(s\) is estimated to be more than 50 min according to real-time traffic data.