Asking for studies about sign font legibility

[peperodriguez2710]

Hello! Some years ago, the government in Spain decided to stop using Autopista (a modified version of FHWA Series E(M)) in freeway signage (white lettering over blue background) to change into Carretera Convencional, a heavier, modified version of Transport Heavy already used for non-motorway signage. Both typefaces are badly done, and the kerning and spacing between lines is usually terrible in both of them. The thing is even worse with Carretera Convencional, which is the heaviest of them and placed without care results in heavy halation.

The problem with the decision for me is replacing an already bad typeface with an even worse one, so I'm going to send a complain to the government asking for valid reasons for the change (as I believe it's made to satisfy road building companies, producing with only one typeface is easier than having to switch it between different kind of signs).
What I do believe we should do in Spain is switch to a more legible typeface for motorways, I thought about FHWA Series E with correct placing, FHWA Series E(M) with correct placing, Dutch ANWB-Ee and Ee VL series with correct placing (the latter isn't as heavy as the others and could have interesting results) and Transport Medium with correct placing. If not possible, I'll ask to at least return to Autopista...

What I want to ask you is: Could you provide me with studies (if known) of sign legibility in the typefaces mentioned before (with a link if possible)? I've already found one about Series E(M) (which I assume is the typeface with more studies from the list because of the comparisons of it vs. Clearview) and I keep searching; but the more I have, the better so please tell me about any study you know about it.

Thanks in advance!