Experimental Jetset explains the design process from initial requirements/workshop/clients likes & dislikes through to all the design elements in all their required scenarios - it's a really interesting look at a very intelligent & detailed design process that shows the amount of thought and iteration that goes into designing a graphic brand.
Also, download the final styleguide at the bottom of the page: "The final and complete graphic manual ('charte graphique'). It was developed in installments; every time a certain design or template was approved, we added it to the manual. Sometimes the city council rejected something, months after the directors had already approved it; in that case, we didn't remove the design from the manual, but just added another chapter, in which we negated the previous chapter. In that sense, it's a manual that really shows the development of the graphic identity; it shows not only the remaining, 'winning' parts, but also the rejected proposals, and the failures."