It is still done with metal boards and photography of the head. I know from some dutch areas, that they do it with telemetry. Maybe you ask Domin Dalessi he might be the best on this topic.
To clarify - I'm asking about national/regional monitoring, not studies of single populations. As such, telemetry etc. are off the table. The only country of which I knew the answer already is the Netherlands. I was wondering if transect counts are done elsewhere, because use of artificial cover has its downsides as a proxy of population size...
In Germany we call it "Biologische Station" which are responsible for protected areas in their region. They do the monitoring in their district and in every state is a different organisation which collect all the Data about herps which are mostly not organized by the government. I don't know if there is a office by the government for that. For my state http://www.herpetofauna-nrw.de/ collects the data.
In Germany we do 10 surveys a year to monitor smooth snake populations. Within the Atlantic biogeographical region there are about 45 sample sites, in the continental region 63 sample sites. Artificial shelters are especially used in grassy habitats and bogs. All data is collected in the federal agency for nature conservation and will be sent to the EU COM in 2019 again. Here is a link, where you will find the monitoring protocol for the species ( BfN & BLAK (2016): Bewertungsschemata Amphibien & Reptilien):