What are lead and lag indicators in construction safety?
Lag indicators measure safety outcomes after they happen, like incidents, injuries and lost time. Lead indicators measure the activity and conditions that come before them, like hazards reported and closed, inspections done on time, toolbox talks held and site induction completion. Lag indicators tell you how you went. Lead indicators tell you where the next problem is likely to come from.
Lag indicators
These are the outcomes most builders already report: incidents, injuries, lost-time injuries, notifiable incidents and near misses that became something worse. They matter, but they arrive too late to prevent the event they record.
Lead indicators
Lead indicators are the signals you can act on: hazards raised and how fast they close, inspections completed on schedule, scaffold tags current, toolbox talks held, SWMS reviewed, inductions done before people start, and plant pre-starts completed.
A rising number of open hazards, or inspections running late, is a warning you can do something about this week.
How to use both
Report lag indicators to show results. Manage with lead indicators. A good project score for safety leans on lead indicators, so a job turns amber when the warning signs appear, not after someone gets hurt.
Getting the data without extra forms
Most of this already sits in your safety system, site diaries and inspection records. The work is pulling it together and scoring it the same way on every job, so supervisors aren't filling in another spreadsheet.
Common questions
Is a near miss a lead or lag indicator?
It's often treated as a lag indicator because something already happened, but tracking near-miss reporting rates can work as a lead indicator of a healthy reporting culture.
How many lead indicators should we track?
Start with a handful you already capture reliably. Too many and nobody looks at them.
Do lead indicators replace incident reporting?
No. You still record and report incidents. Lead indicators sit alongside them to warn you earlier.
Can these be tracked automatically?
Yes, when they're read from your safety and site systems rather than typed into a separate report.