Do not abbreviate or contract name tags; for example, use Saint Margaret instead of St Margaret. Why? Think search engine design; maximal up-front quality information, automated presentational reduction for dense cartography (e.g. OS A–Z). The short_name key is ideal for this.
According to Department for Transport, dual carriageway on/off-slips are 60 mph NSL unless otherwise stated.
Areas worked on:
Speed limits (prefer GB:national over GB:nsl_single),
Tertiary/Unclassified road references (highway_authority_ref),
Public transport routes,
Winter salting routes,
Give-way signs (for routing cost estimates at same classification cross-roads),
The 16 months it took TeleAtlas to update their map after I reported car/truck-blocking bollards near my home with a photo. In that time frame, I had contributed to Norwich mapping to near total road network completion. The continued uselessness of TomTom at updating their own map from volunteered speed limit feedback. The abhorrent tax upon tax upon tax of OS maps.