This is a perennial subject. Roads in the Democratic Republic of Congo are just so unpredictable and can delay travel literally for weeks.
A compelling, brilliantly edited film shown on Al-Jazeera recently, “Hazardous trucking in DR Congo” provides a graphic account of a truck journey – 650km that should have taken a few days and turned into a one-month mud battle. If the film leaves that link I imagine you’ll find it one YouTube (Tony Comiti productions for Al Jazeera).
In contrast, Bukavu in eastern DRC has some excellent roads, at least in town, as these photos on SkyScraperCity.com show.
For some good insights into the condition of roads between Bangui and Rwanda (ie the old route across what was then Zaire), have a look at Pete Gostelow’s superb photos and descriptions of cycling (and going by river) through DRC in early 2011.