Sure.
It's an objective approach to decision making.
In this case, the problem is not whether we should have cycle lanes or not. I would take it up to the most abstract goal first; we want to enable travel through our city. Then bring in context, travel in several different modes, what the stats on effectiveness, safety, whatever other elements.
What the problems are - this would take some analysis.
The specific elements and goals, say to encourage cycling. Desired safety levels, ie deaths per million miles or whatever.
Then analyse all the ways similar problems have been addressed elsewhere, and hownthey might be appropriate or inappropriate for London.
Now obviously this is a strawman, but by laying out this level of definition nixes all arguments about desiring speed - it's not the goal, safety is.
You progress like this logically and rationally until you have all the pros and cons, and their relative importance until it is clear what the preferred solutions are.
Then a cost benefit analysis should wittle it down to one. If two or more remain, then you can choose randomly because your analysis has already satisfied the need.
Thanks for that - I finally get what your saying. Whilst I do agree that some proper homework should indeed be done, but I don't agree that this type of problem can be reduced to a calculation or "objective" decision. The trouble is, even in your example, "desired safety level" is itself a value judgement. (I'm only using this as example - same would apply to most criteria) .
How building such a thing would affect future behaviour, eg cycle take-up, increased or reduced risk etc would inevitably be speculative, even without bias. Ultimately someone has to choose, rather than work-out, what to do.
Regarding your job - just curiosity, but what are these objective decisions you make? I'm guessing it's something more amenable to such treatment, rather than policy type decisions, but if the later, I'd be sceptical of real objectivity.
That's not to say a scientific approach to the investigation isn't very worthwhile (usually), but it won't usually give you the "answer to life the universe and everything". And on another Adamsian note, in his Dirk Gently book, nefarious agencies were providing the right questions to ask, in order to get the policy answer you wanted - which is a big danger for false objectivity