The mobile signs have started life in Sunderland's East Area which includes the Doxford, Hendon, Millfield, Ryhope and St Michael's wards.
All the signs, which run on renewable solar energy with a battery backup, have motion activated happy or unhappy smileys. Funding of £42,000 has been provided by the City Council's East Area committee.
Committee Chair and Ryhope ward Councillor Ellen Ball, said: "Residents regularly comment on how too many drivers are breaking speed limits. This is a road safety priority for our residents and therefore it's a priority for the council and our area committee.
"Yes, the vast majority of drivers are keeping within the speed limits but there's a minority of irresponsible and dangerous drivers who are a danger to everybody else with their driving speeds.
"Research indicates that these signs do have an effect on drivers and, as speed is a factor in many accidents, they are now helping make our roads and communities safer.
"The smileys, and most drivers will have seen them, react quickly and give a very simple and straightforward message - either you're driving within the speed limit or not."
The signs are mobile and being rotated across 30 locations within the east area.
Current locations are: Tunstall Bank and Moorside Road in Doxford; Villette and Commercial roads in Hendon; Chester and Hylton Road in Millfield; Black Road, near the Infant School Academy, and Stockton Road, Ryhope; plus Essen Way and Silksworth Lane in St Michael's.
Cllr Ball added: "Working closely with council highways staff, we can re-locate the signs quite easily and so speeding drivers will be getting warnings across our community in east Sunderland."
In Cllr Ball's ward, the two signs are currently in Black Road and Burdon Lane at Cherribank.
Councillor Amy Wilson, the City Council's Cabinet Member for Environment and Transport, added: "These signs are all about safety - road and community safety. We all want safer communities and these simple but effective messages help make our city safer for everybody."