Suggestion: account for lane count, overtaking rules when calculating speed penalties for cars

[lordsutch]

At present, the speed penalty for the default speed limit (or tagged speed limit) does not take into consideration roadway characteristics associated with overtaking (passing), such as explicit restrictions and available lanes, that are likely to impact the driver's ability to maintain the posted (or implied/legal) speed limit.

For example, where overtaking is permitted, we'd expect a vehicle to be able to overtake a slower vehicle more easily if there are multiple lanes in the travel direction (i.e. oneway with lanes >= 2 per default, or not oneway with lanes:forward/backward >= 2) than if there is a single lane. If overtaking is not permitted, we'd expect it to be even harder to maintain the speed limit as the slowest vehicle in a line/queue of vehicles will be the limiting factor.

Here's an example of a way with a passing lane that illustrates the potential benefit of accounting for the lanes tagging - northbound vehicles will be able to pass slower-moving traffic, while southbound vehicles will have difficulty doing so: https://www.openstreetmap.org/way/1013933988

I'd suggest a lower baseline penalty of 10% (from the existing 20%), with an additional 10% on two-way roads with just one lane in the travel direction.

A further 10% penalty if overtaking is not allowed (implicitly on a one-way road with just 1 lane, where there is presumably no space to pass, or if explicitly tagged a one-way road with >= 2 lanes or on a two-way road due to posted restrictions) should be included as well - if there is a minspeed or maxspeed:* for certain vehicle classes like HGVs, PSVs, etc., I'd suggest using this limit (perhaps with a 10% penalty) instead of a penalty based on the maxspeed limit since drivers are more likely to get stuck behind such vehicles.