This value in the speed field you can ignore. It's not used anywhere and indeed it's an error since it is affected by the editing of a segment (I.e. if this segment was changed, it's length was changed and hence it's speed was altered since the time it took to drive it is a constant). We'll either correct it or remove this field all together.

We are looking to add the altitude collection as well (if possible)

even if the altitude could not be used to diferenciate two crossing roads, you could record this parameter, in order to make a 3D map in the future. For example, lets say that I want to go to a mountain.... if you see that all the road you get higher and higher altitude, you could draw in a 3D map as a mountain

It's better to record more data, becouse recording the road information it's not easy, and we don't know future applications that we could use.....

It's only a opinion

Regards and sorry for my bad english