The impact of 20mph speed limits in Edinburgh is to be examined in a new study.

Edinburgh University researchers will evaluate how the policy of reducing the limit from 30mph has worked in parts of Edinburgh and Belfast.

The study, which will run until 2020, is funded by the National Institute for Health Research and is the largest of its kind in the UK.

Rates of traffic accidents and injuries before and after the change will be measured to look at whether or not road safety has been enhanced.

Any change in transport use will also be considered by examining the take-up of cycling and walking, while local residents will also be asked their opinions of the move.

Dr Ruth Jepson, from the university's Usher Institute of Population Health Sciences and Informatics, 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.

"We anticipate that our broad focus will generate a wealth of evidence and learning that will be invaluable for informing future roll-outs of similar schemes in the UK and around the world."

Andy Cope, director of insight, research and monitoring at Sustrans, said: "This study will provide vital intelligence on the impact of 20mph speed limits on safety and levels of physical activity.

"We await its findings with keen interest."