Environmental and Site Conditions: Wind, Powerlines and Ground
Wind is the most common environmental cause of tower crane incidents. Manufacturers specify maximum in-service and out-of-service wind speeds, and the crane must be configured for out-of-service conditions (slewing free or braked as specified, trolley positioned as specified, hook raised). Wind speed must be measured at the crane, not forecast at ground level, using the anemometer. Wind acts on the load's sail area as well as the crane, so a large flat panel can become uncontrollable well below the crane's own limit. Gusts, funnelling between buildings and sudden changes all matter.
Overhead powerlines require a documented control: de-energising and proving dead is the strongest control; otherwise isolation, physical barriers, goal posts, marked limits and a spotter are used, with the crane's stipulated safe approach distance observed. Assume lines are live and that electricity can arc across an air gap. If contact occurs, the operator should stay in the cab and warn others away unless fire forces evacuation, in which case jump clear and shuffle away.
Ground conditions affect crane stability and mobile crane set-up: soft ground, voids, backfill, slopes and drainage all reduce bearing capacity. Weather also brings heat, cold, lightning, rain and poor visibility, each with its own controls.
Traps: relying on a forecast rather than the crane's anemometer; using the in-service limit for an out-of-service situation; forgetting load sail area; and assuming a spotter makes powerline work safe without distance controls.
Rule of thumb: if the load or the wind is uncertain, stop - wind limits are hard limits, not targets.
Shutdown, Securing, Emergency Procedures and Incident Response
End-of-shift shutdown is a defined procedure, not simply parking the crane. Typical steps: land and secure the load, raise the hook to the specified height, position the trolley and slew as the manufacturer requires for out-of-service wind, apply slewing and travel brakes as specified, isolate power where required, secure access ladders and gates, and record the state of the crane in the log. Out-of-service configuration matters because the crane may face much higher winds overnight than during the shift.
Emergency procedures must be known before they are needed: emergency lowering of a person or load, response to a limit device failure, fire, lightning, powerline contact, structural damage, and loss of communication. The operator's priority is to make the situation safe, warn people, and follow the site emergency plan. After any incident - dropped load, contact, overload, structural damage, or a near miss - the crane should be taken out of service, the area secured, the incident reported and recorded, and the crane inspected by a competent person before returning to service. Preservation of evidence and witness details supports the investigation.
Traps: leaving the crane in working configuration overnight; resetting a limiter and continuing without investigation; returning a crane to service after an incident without competent-person inspection; and treating near misses as not worth reporting.
Worked example: a load is dropped from height with no injury. Correct response: stop work, secure the area, report as a dangerous incident, preserve evidence, inspect the crane and gear, investigate causes, and only return to service after sign-off.