# Benefits of Advanced Air Mobility for Society and Environment: A Case Study of Ohio
## 4 Benefit Factors
### BF-4: Time and Inventory Cost Savings in Cargo Delivery by eVTOLs  
#### 4.4.1 Cost Savings in Inventory  
Inventory warehousing cost is not a value-added activity as it raises the price of the goods or service without increasing the customer's value. The use of Just in Time (JIT) inventory system aids in the reduction of non-value-added inventory expenses [53]. Manufactures will benefit from the use of eVTOLs for cargo delivery because they will increase JIT deliveries, which will in turn minimize the warehousing expenses by reducing the warehouse inventory. By delivering high-value products using eVTOLs through logistics air corridors, distribution operators and logistics companies can supply freight and cargo to regional industries faster [31]. Suppose a logistics company can deliver \(x\) number of products every year through the traditional approach. Using eVTOLs, it would be able to deliver \(x\) number of products in less than a year. Let the time difference be \(y\) months, which means \(x\) number of products will not be stored for \(y\) months in the warehouse. Thus, here, the cost reduction is the cost saving related to operating a warehouse \(y\) months fewer. This cost saving can be used to store more products or support other activities related to the company. We assumed \(d_{1}\) miles as the average trip distance for cargo delivery (see Section 4.1). From [31] report, we obtained the estimated cargo revenue for next 25 years. According to that report, carrying 1.2 million tons (1 US ton = 2000 lb) of cargo will produce more than $2.1 billion in revenue over the next 25 years. In each trip, an eVTOL is expected to carry 50-1000 lb (average payload \(p^{e}=525\) lb) commodities. From these data, we calculated the number of estimated AAM cargo trips (**T**) for the next 11 years for our analysis. Using \(s\) from Section 4.1, \(S_{t_{i}}\), which refers to the delivery time saved by the annual AAM cargo trips (unit in month), can be calculated as:  
\[S_{t_{i}}=\frac{T_{i}\times s}{30\times 24\times 60}\qquad i\in\{2022,2023,...,2 032(year)\}. \tag{20}\]  
Three metrics commonly used to calculate how much a warehouse will cost each month are: (i) monthly base rental charge, (ii) facility size (in square feet (sf)), and (iii)expected operational costs (also called NNN). Table 2 shows the average base rent \(r\) (unit in $) and average size \(z\) (unit in sf) for a warehouse in SMCO [54]. A _Triple Net Lease (NNN)_ is a leasing structure in which the tenant is liable for all running expenditures associated with a property, such as building insurance payments, utilities, HVAC (heating, ventilation, and air conditioning) maintenance, and property taxes [55]. We considered NNN for a warehouse (\(o\)) as $0.25 per sf per month [56], and the average yearly wage of a warehouse worker (\(w_{1}\)) as $27,867 [57]. In 2017, the average area of workplace in America's warehouse dedicated to each employee (\(a\)) was 138 sf [58]. Using Equation (21), the average cost to operate a warehouse (\(W\)) can be calculated:  
\[W=(r+o)\times z+\frac{z}{a}\times\frac{w_{1}}{12} \tag{21}\]  
Using Equation (22), we calculated \(CS_{i}^{c}\), the cost savings in cargo delivery in year \(i\) by using eVTOLs:  
\[CS_{i}^{c}=S_{i_{l}}\times W\qquad i\in\{2022,2023,...,2032(year)\} \tag{22}\]  
Truck-trailers are commonly used for transporting cargo within a state. The weight limit for these trucks operating on Ohio's interstate highways is 48,000 lb [59], with a payload capacity share relative to empty weight is 200% [60]. Thus, a full truck can carry around \(p^{t}=\)24,000 lb commodities per trip, whereas we considered the average payload of eVTOL as \(p^{e}\).