The impact of 20mph speed limits is to be evaluated in a major study in Edinburgh and Belfast.
Casualties and traffic accident rates will be measured to determine whether 20mph limits improve road safety. Rates of cycling and walking will be measured to assess the impact on transport use.
Experts say the project, which is the largest of its kind in the UK, will also investigate wider effects on residents and the local area and will inform other cities planning to introduce lower speed limits.
Dr Ruth Jepson, Lead for Evaluation Research at SCPHRP, said: “We are excited to launch this major project, which we hope will provide very important insights into the public health effects of such initiatives.”