This is Albert Road, Southsea, Portsmouth looking east. It's 30 mph and is not full downtown Portsmouth that is a bit of a complex of roundabouts and a building site where the infamous Tricorn shopping centre has been demolished.
This stretch of the road has a cycle lane
It is a pretty green colour, running alongside the parked cars but with a bit of a gap -provided the car is a sensible size. Note also the lack of no central lane markings in the road.
Note also the need for signs to warn cars of bikes, as if they are unexpected. The cars all keep an eye out for bikes while they drive down with one wheel in the green lane.
Further west, there are some vans doing some unloading; the green lane places bikes in exactly the right place to get "doored".
If you were cycling round here you have a choice: quiet but windy back roads with an impermeable one-way system but with 20 mph speed limits, or the main road with pedestrians, through cars in a hurry, and a bike lane that doesn't really look that safe.
An alternate option: provide short stay parking for cars on both sides of the road but dropping the speed limit to 20, essentially downgrading it from a through road to a shopping road does not appear to have been explored.