[50] Wandel et al. (1992) describe the interface between shippers and LSPs in terms of a logistics market (Figure 1 [Figure omitted. See Article Image.]). In this market, the need for material flows and demands for logistics services by shippers meet, and hopefully match, the LSPs' system for transport flow and supply of logistics services. Similarly, [43] Sheffi (1986, p. 2) describes the transportation market thus:
Interactions between carriers and shippers can be considered supply and demand actions in a freight transportation "market". In the transportation market, carriers "supply" and shippers "consume" transportation services.
The efficiency in the match between supply and demand can be measured in terms of service quality.
The development of green logistics services is an active interface between the demand and supply sides, where both sides pressure and respond to each other ([33] Martinsen and Huge-Brodin, 2010). In the following paragraphs, green supply and demand in the green logistics market are presented, after which environmental considerations in this market are discussed.