## 5 Discussion
However, that seems in partial contrast to the findings of the work by [9], which indicate location as \"attractive\". In this work, the shippers' logistics managers were interviewed and they focused on reducing transportation costs, placing the warehouse in the centre of gravity of their flows. However, for the 3 PLs, this is important, but not as much as for the shipper. As a point of \"interface\" between the inbound and outbound flows, to let the 3 PL reduce the delivery lead time and the order processing cost (in terms of transportation costs), the warehouse should be in proximity to the shippers' customers, specifically in a barycentric location for all their flows. However, location is not strategic since customers and their logistics network could change. On the other hand, for the 3 PL, it is essential to provide flexibility through location; the warehouse must be located near industrial or logistics areas or in proximity to the main logistics infrastructure (e.g., highways) in order to access skilled personnel or expand the building in case of potential demand peaks. However, in terms of the selection or construction of a warehouse, 3 PLs find the facility features more attractive, probably because they see a stronger connection with the execution of the warehouse activities rather than with the facilitation of the inbound transport and outbound distribution processes. 3 PLs see more critically the issues related to land use (probably out of the remit of their potential decisions and linked to exogenous factors, such as availability of land and infrastructures). The land development patterns for logistics use are influenced by access to select locations in the urban area, such as major highways and the airport [31]. Placing logistics buildings in logistics clusters (such as logistics parks) can help 3 PLs to benefit from geographical aggregation, as shown by [46]. External spaces are instead considered a \"must-be\" (\"M\") to achieve flexibility, on-time delivery, and productivity. A wide yard and a high density of loading/unloading bays are requisites for a good level of service (punctuality and flexibility) and productivity. These elements are considered essential enabling factors, and they act as \"filters\" in the selection of warehouses. Warehouses unable to satisfy the requirements of good external areas are not even shortlisted in the selection process for 3 PLs. This confirms the evidence reported by [21]. Another interesting finding could be drawn from the warehouse indicators against the features. The location appears to be the most critical warehouse feature to improve the delivery lead time, while the others are judged to be indifferent. This result is in line with the literature discussed. The relationship between location and delivery performance has been widely analysed; [31] investigated the importance of accessibility (in terms of the relationship between the location and the travel time) to discuss the logistics land use in a city. Likewise, locations drive on-time delivery, enabled by the external spaces considered must-be features. Researchers noted that the number of loading/unloading bays comes into play when measuring delivery performance [21]. Flexibility is driven by the building features (size and layout) and enabled by the other must-be warehouse features. Responsiveness is again driven by location, but internal areas and building features are must-be factors. As noted by [47], responsiveness is linked to the transportation service; normally, customers' demand is related to changes in shipping. Therefore, location (in terms of accessibility) is the most critical element. The completeness of the logistics service is associated with the size of the building, and the same can be said for labour productivity, for which the building's features (precisely the layout and size) can even be a differentiating element (attractive). The order processing cost seems to be driven by the location and the external spaces, probably because it is seen as a matter of order shipping.