How ride safety works

The part of the magic nobody sees

When guests step off a coaster or walk past an animated figure, the only thing they should remember is the story. Behind that is a long chain of calculations, checks and signatures, from the first design review to the daily test run before the gates open. If you want to design attractions, you have to understand that chain, because it shapes every decision from the first sketch.

I want to work on animatronics and attractions, so I wanted to understand the rules a design has to meet, not only the creative side. A note before I start: the full ISO standards are paid documents, so my notes on them come from the official summaries, tables of contents and previews. The UK guidance and the ADIPS scheme document are free, and I've read those directly.

ISO 17842: three parts, one ride's life

ISO 17842, Safety of amusement rides and amusement devices, is written by the ISO technical committee ISO/TC 254. It's split into three parts that follow a ride from drawing board to daily operation [1–4].

Part 1 covers roundabouts, swings, Ferris wheels, roller coasters, chutes, booths, side shows and similar devices. It leaves out things that have their own standards, such as grandstands, playgrounds, waterslides, trampolines and inflatables [2].

The annexes I found most interesting

The table of contents for Part 1 reads like a checklist for anyone designing an attraction [2]:

• Annex A, Electrical equipment and control systems. This annex is normative, which means it's part of the requirement rather than advice.
• Annex C, Guidance on design of passenger containment: restraints, lap bars and harnesses.
• Annex E, a list of hazards for passengers and spectators.
• Annex F, Guest behaviour. Guests won't always do what the designer expects.
• Annex G, Limited accessibility to amusement devices.
• Annex H, Safety envelope for passengers: the space a rider can reach, which nothing is allowed to intrude into.
• Annex I, Acceleration effects on passengers: the forces a ride's motion has to stay within.

Europe has a parallel series, EN 13814-1, -2 and -3 (2019), with the same three-part split [5]. The UK inspection scheme references both.

Law, guidance and a scheme

In the UK, ride safety works in three layers.

• The law. The Health and Safety at Work etc. Act 1974 puts duties on everyone involved, including the designers, manufacturers and suppliers of equipment. The Provision and Use of Work Equipment Regulations 1998 (PUWER) require equipment to be inspected.
• The guidance. HSE's HSG175, Fairgrounds and amusement parks: guidance on safe practice, was written with the industry. It isn't law, but following it is normally enough to comply with the law [6].
• The scheme. ADIPS, the Amusement Device Inspection Procedures Scheme, is how the industry carries out the inspections HSG175 describes. It's run by the Amusement Device Safety Council, made up of the major trade associations, through ADIPS Ltd, and it's supported by HSE [7, 8]. HSE says an ADIPS inspection will generally meet PUWER's inspection requirements [9].

Who does what

Three checks before the first rider

Before a ride carries its first passenger in the UK, and again after any safety-critical modification, it needs three independent pre-use inspections [6, 7]:

1. Design Review. Has the designer addressed the safety issues the ride will face over its whole life? This covers the calculations and the assumptions that testing can't prove, like fatigue life.
2. Assessment of Conformity to Design. Do the safety-critical parts of the ride that was actually built match the design that was reviewed?
3. Initial Test. Do those safety-critical parts work as intended?

After that comes the in-service annual inspection, at least every 12 months. It covers mechanical and structural condition, electrical safety, a functional test, and non-destructive testing of critical welds and components. Any defect that poses imminent danger has to be fixed before the ride passes [7, 8].

On top of that, the controller does a written daily check before opening. It covers safety controls, brakes, communications, barriers, guards and locks, plus at least one complete ride cycle, and the records are kept for at least three years [6].

Who's allowed to inspect

Inspection bodies have to be Type A or Type C inspection bodies under ISO/IEC 17020, and those accredited by UKAS for the same scope can register automatically. Individual inspectors are registered by qualification group. Design reviews are reserved for the top two groups: Chartered or Incorporated Engineers, or people with an equivalent degree or HNC plus at least three years' engineering experience [7].

The Declaration of Operational Compliance

Once all the required inspections are complete and satisfactory, the inspection body hired by the controller issues a Declaration of Operational Compliance, or DOC. It's normally valid for 12 months, or less if one of the underlying inspections expires sooner [7, 8].

The detail I liked most: the DOC's real status lives on the ADIPS database, not on paper. ADIPS compares it to an MOT. A printed DOC only shows the status on the day it was issued, and it can still be passed around after the record has been withdrawn, so you check the DOC number online [8]. Local councils often ask to see DOCs before licensing an event, though HSE leaves that decision to each council [9].

A ride's safety certificate is the database record, not the piece of paper.

What it means for the things I build

None of my projects has been through a design review, and I'm not claiming they were built to the standard. But reading it has changed how I think about them.

Animatronics: the envelope and the failure

My Projected Head moves its neck with hobby servos, driven from an ESP32 through a PCA9685 servo board. In a show space, the first question wouldn't be how good it looks. It would be what a guest can reach, and what the figure does when something fails. Annex H's passenger safety envelope and Annex A's electrical and control-system requirements frame those questions. What happens on a power loss or brown-out? If the controller crashes, the servo board keeps holding the last pulse it was given, so where is the head left? Is there a stop that doesn't depend on software? The closed-loop steppers I've proposed for revision 2 help here too: unlike hobby servos, they can detect when an axis has stalled or been blocked.

Coasters: forces on the rider

My NoLimits 2 to CAD pipeline takes a simulated coaster into SolidWorks. On a real ride, the forces that track puts on riders are exactly what Annex I sets limits for, and checking that the built track matches the reviewed design is what an Assessment of Conformity to Design does.

Documentation as a design output

A ride arrives with a design risk assessment, an operations manual, inspection and maintenance schedules and a log. It's a mature version of the habit I already try to keep in my case studies: write down why each decision was made, so the people who build, run and maintain the thing can trust it.

What I'm taking away

• Safety follows the whole lifecycle. Design, build, installation and every operating day each have their own check, and each check needs the paperwork from the one before.
• Independence is the point. The person who checks a design can't be the person who drew it.
• Design for failure, not just function. For a moving figure, the important question is what it does when the power, controller or a motor fails.
• Motion is a safety decision. Changing how a ride or figure moves, including in software, can need a new inspection.
• Write it down. Design reviews, inspections and daily checks all rely on the designer's documentation being clear.

Sources

1. ISO (2023) ISO 17842-1:2023 Safety of amusement rides and amusement devices, Part 1: Design and manufacture. ISO/TC 254. iso.org
2. BSI (2023) BS ISO 17842-1:2023, preview: scope, national foreword and contents. webstore.ansi.org
3. ISO (2022) ISO 17842-2:2022 Part 2: Operation and use, preview: contents. webstore.ansi.org
4. ISO (2022) ISO 17842-3:2022 Part 3: Requirements for inspection during design, manufacture, operation and use, catalogue entry. iteh.es
5. CEN (2019) EN 13814-1:2019 Safety of amusement rides and amusement devices, Part 1: Design and manufacture, catalogue entry. iteh.es
6. Health and Safety Executive (2017) HSG175 Fairgrounds and amusement parks: guidance on safe practice, 3rd edn. Free download. hse.gov.uk
7. ADIPS (2020) Amusement Device Inspection Procedures Scheme: Inspection Scheme Document, Issue 007 Rev 001. adips.co.uk
8. ADIPS, About Inspection and FAQs. adips.co.uk · adips.co.uk/faqs
9. Health and Safety Executive, Advice to local authorities regarding ADIPS DOCs. adips.co.uk