Escalators & Moving Walks

Escalators and moving walks carry large numbers of people between levels or along concourses in shopping centres, transport interchanges, airports, offices and institutions. Each comprises a steel truss, a drive machine and brake, step or pallet chains carrying steps or pallets, handrails driven in step with the treads, comb plates where people step on and off, skirt panels beside the steps, and a set of safety devices that stop the unit when something goes wrong.

Escalators are among the most heavily used and most injury-prone pieces of building equipment; most injuries involve falls, often linked to handrail speed mismatches, abrupt stops or passenger behaviour, and entrapments at comb plates and skirts.

What shortens life:

• Duty beyond what the unit was designed for.
• Outdoor exposure.
• Poor lubrication.
• Trolleys and luggage.

The duty an escalator was designed for matters as much as its age. A commercial escalator moved into a transport interchange, or a shopping centre escalator running longer hours than designed, wears through chains, steps and drives years early. Heavy-duty units built for public transport have heavier components and longer intervals between major overhauls.

• Excess duty: more hours, more passengers or heavier loads than designed.
• Outdoor and semi-outdoor exposure: rain, dust and salt corrode trusses, chains and steps, and water collects in the pit.
• Poor lubrication of chains and drives, which accelerates wear and noise.
• Trolleys, prams and luggage on units not designed for them, which damage steps and combs.

Step chain and drive wear

Step chains elongate and their rollers wear, so steps run unevenly, gaps open between steps, and noise and vibration grow. Drive chains and gearboxes wear with heavy duty and poor lubrication. A broken step chain or drive chain without working protection devices can let steps run back.

Comb plate and skirt entrapment

Broken comb teeth, excessive gaps between steps and skirts, and missing skirt deflectors create entrapment points for shoes, fingers and clothing, particularly for children.

Handrail faults

Handrails crack, stretch, slip and run at a different speed from the steps; passengers holding a lagging or leading handrail lose balance. Handrail inlets where the rail enters the balustrade are a finger entrapment point.

Brake and stopping faults

Brakes that stop too abruptly throw passengers; brakes that stop too slowly do not hold a loaded escalator. Stopping distances are tested against limits.

Safety device failure

Comb plate switches, handrail inlet switches, missing step detectors, overspeed and reversal protection, and emergency stops must all work. Devices bypassed during maintenance and not reinstated are a serious hazard.

Step damage

Cracked or broken steps, missing demarcation lines, and damaged cleats cause trips and entrapments.

Controller obsolescence

Controllers lose manufacturer support like lift controllers; escalators are usually replaced or modernised as a whole rather than in many small stages.

Water and debris in the lower pit also corrode chains and drive components and can short electrical equipment, especially on outdoor and semi-outdoor units.

On site

• Comb plates: broken or missing teeth, and the gap between comb and step.
• Gaps between steps and skirt panels along the incline; skirt deflector brushes present and intact.
• Handrail speed against step speed, cracks and gloss loss on the handrail, and inlet guards where the rail enters the balustrade.
• Noise, vibration and uneven running of steps, felt by standing on the unit.
• Step condition: cracks, broken cleats, missing yellow demarcation lines.
• Emergency stop buttons at both landings, accessible and labelled.
• Water, debris and corrosion visible in the upper and lower landing pits during maintenance.

In the records

• Breakdown, entrapment and injury records, with causes.
• Maintenance logs and safety device test records.
• Periodic inspection certificates.
• Modernisation or replacement history, and duty data where monitored.

Falls usually point to handrail speed, abrupt stopping or step irregularities; entrapments point to combs, skirts and inlets. Recording the location and cause of each incident shows which component needs attention.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

An independent lift and escalator consultant leads, with the maintenance contractor operating the unit; testing needs the unit out of service and landings protected.

• Records review: breakdowns, entrapments and injuries over several years, maintenance hours and scope, inspection findings.
• Component inspection with steps removed: step chains and rollers (elongation measured), steps and pallets, drive chain and machine, brake, truss, tracks and lubrication.
• Safety device testing: comb plate, handrail inlet, missing step, overspeed and reversal protection, emergency stops, skirt switches.
• Stopping distance tests against the limits for the unit, unloaded and where possible loaded.
• Handrail speed measured against step speed on both sides.
• Gap measurements between steps, skirts and combs.
• Duty assessment of current traffic against design, and controller parts support.

The report should state safety defects, component condition and remaining life, whether the unit suits its duty, and whether to repair, modernise in the existing truss or replace.

• Comb plate and step replacement wherever teeth are broken or steps damaged, with demarcation lines renewed.
• Handrail replacement on its cycle, with drive adjustment so speed matches the steps.
• Step chain replacement when elongation reaches the limit, often with step rollers and tracks.
• Safety upgrades: skirt deflectors, handrail inlet guards, missing step detection and other devices required by current standards.
• Modernisation in the existing truss: new drive, brake, controller, chains, steps and handrails, which avoids removing the truss.
• Full replacement where the truss is corroded, the unit is unsuited to its duty, or modernisation is uneconomic.
• Weather protection and pit drainage for outdoor units.

Maintenance is a recurring contract, and handrails, combs and steps are replaced as recurring repairs. Modernisation in the truss is a lump sum per unit with a planned outage of several weeks. Full replacement is a larger lump sum that includes removal and installation through building openings or by crane, structural and finishes works, and a longer outage; in shopping centres and stations the disruption cost to tenants and operators often shapes timing.

Modernisation and replacement are lifecycle; safety upgrades are code compliance; component replacement is repairs and maintenance.

• Australia. Escalators and moving walks are registered plant under state work health and safety regulations, with design and modernisation to the AS 1735 series (now aligned with EN and ISO standards) and periodic inspection where state rules require it.
• United Kingdom. BS EN 115-1 governs design and installation, and BS EN 115-2 the improvement of safety of existing units; PUWER 1998 requires maintenance and inspection, and the HSE has issued guidance on escalator safety.
• United States. ASME A17.1 governs escalators and moving walks, with periodic inspections and tests (including brake tests) set by state and city elevator authorities, and A17.3 for existing units.

Accessibility rules in all three jurisdictions do not treat escalators as an accessible route, so a lift must be available wherever an escalator links levels; taking a lift out of service at the same time as an escalator modernisation can break that requirement.

• Breakdown, entrapment and injury records with causes.
• Maintenance contract, scope and hours.
• Periodic inspection certificates and outstanding defects.
• Safety device and stopping distance test records.
• Modernisation or replacement history and recommendations.
• Manufacturer parts support advice for the controller and drive.
• Traffic and duty data where available.