There is another aspect to consider when designing and implementing transportation solutions. Any time you want to automate business knowledge, or experience when simplified, one could overdo configuration and rules pretty easily. Every time when introducing another powerful application in the SAP Business Suite, that is one of the challenges the design team and the solution architects have to face. Like in 2000, when SAP launched its powerful gATP (global available to promise) as one central component in SAP APO, in the first release of APO 1.1, the maintenance of rules, access sequences, business events, etc. consisted of more than 10 tables you had to maintain, link (and understand) one after the other. With later releases, an "integrated rule maintenance" had been introduced, which made life much easier. Then, the real threat was, to not overload the complexity of rules, but from my perspective, start simple and grow over time.
Same thing with BRF+ now in SAP Transportation Management (SAP TM 9.0, SAP TM 9.1, SAP TM 9.2). It is really powerful and we have great success in using it in productive projects to easily model in TM really complicated, local, and global Routing Guides of customer and supplier routing contracts and services in all modes of transport. (you might want to browse in our blog history to eventually learn more about BRF+ what e.g. Samir posted a few months ago). What I think, one of the strengths of SAP TM is certainly the powerful architecture and the straightforward integration of the latest development frameworks and toolsets, like BRF+ is easily connected in TM via Conditions, FPM (floor plan manager) is integrated into TM via the FBI with the Back end technology with BOPF, etc.
So coming back to the routing questions, we did it using BRF+, but as Thorsten pointed out in his blog yesterday, even with the movement types and default routes, there are powerful rule and condition driven features in SAP TM, which give you a powerful framework to model out of the box a routing guide, to process those shipments in your supply chain which can be processed for whatever reason directly. Examples for that for sure also for shippers could be FTL, LTL (if you have the contracts in place for that), FCL or Express, Parcel, etc. Now, if you want to rate shop through your different options you may want to include here then DSO to browse through your carrier rates in real-time with SAP TM. Not enough? Then connect also in real-time with SMC3's Czarlite business logic to check your carrier's best rates online.
Still, in Europe as well as in the US, especially if you not only operate your own fleet but also work with dedicated fleets of your Logistics Service Providers and Carriers, there is certainly the legal implication of being a responsible shipper. Quote from an owner of a logistics company in Germany: "As a planner or owner of a logistics company or running a logistics department, you are always with one foot in jail, considering the legal responsibility you have even for a driver, you don't know, because you have to deal with his driver time". Looking to Europe and especially Germany, where electronic driver cards are recording breaks, stops, and working hours for several weeks, you need to inherit in your planning and consolidation design during implementation changes from a legal and hours of service regulation perspective.
Having pending updates on the hours of service regulations in the US is important to be considered during implementations. I found the following article on logistics management you may find interesting in this context. HOS driving trucking rates increases, carriers say. In TM certainly hours of service are also supported at a means of transport level, which surely helps to build consistent rates and allow adjustments considering the longer breaks according to DOT regulations. You would need to use planning constraints for that (and as Bernd Dittrich highlighted before, there is information in the TM documentation)
References: SAP Netweaver, SAP Transportation Management, SAP Event Management (SAP EM 9.0, SAP EM 9.2)