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Technical

Gangways, Access, DDA and Public Safety

AustraliaUpdated 11 September 2026

Gangway running down to a floating pontoon with boats alongsideXimonic (Simo Räsänen) · CC BY-SA 4.0
shore abutmenthigh water — shallow gradientlow water — steep gradienttidal rangeGradient is set by gangway length against the full water-level range, not by the average.
The same gangway at high and low water — gradient follows the full water-level range.Diagram: Australian Pontoon Buyer Guide

Key takeaways

  • Gradient must be assessed at the extremes of the water-level range, never the average.
  • Length is the main lever on gradient — and it costs space and structure.
  • Public and passenger facilities carry accessibility obligations that private ones may not.

Gangway length is controlled by water-level range and acceptable gradient.

Buyers should specify

  • clear width
  • maximum operating slope
  • design crowd load
  • handrails
  • kick plates where needed
  • non-slip deck
  • hinge and roller arrangement
  • shore landing geometry
  • lighting
  • wheelchair/accessibility requirements
  • emergency egress

Public ferry and passenger facilities can be subject to transport accessibility obligations beyond ordinary marina practice.

Common residential mistake

A short gangway is cheaper and looks compact at high tide but can become steep, slippery and difficult at low tide. Always inspect geometry at both extreme water levels.

Gradient is a range, not a number

The single most common access mistake is designing the gangway for the average water level. The gangway has to be acceptable at the extremes, because that is when people actually struggle — and in tidal water, the extremes arrive twice a day, every day.

Length is the main lever. A longer gangway spreads the same vertical movement over more horizontal distance and flattens the worst-case gradient, at the cost of space, structure and money.

Questions to settle before you specify

  • What is the full water-level range used for the design, and where did those levels come from?
  • What is the resulting gradient at the highest and lowest levels?
  • Who uses the facility, and does the answer include people with limited mobility, children, or people carrying gear?
  • What happens at the top and bottom transitions, where the gangway meets the shore and the pontoon?
  • Are handrails required on both sides, and at what height?
  • What is the surface, and does it stay usable when wet?

What to put in the RFQ

  • Design water levels and their source, with the gradient calculated at each.
  • Gangway length, width and clear width between rails.
  • Hinge and roller arrangement at both ends, with the movement range they allow.
  • Surface treatment and its wet slip performance.
  • Handrail configuration and any kickplate or edge protection.
  • Load basis, including whether crowd loading applies.

Where access designs go wrong

  • Gradient checked at mean water only.
  • Rollers that jam or run out of travel at the extremes of the range.
  • A gangway that is compliant in geometry but has an awkward step at the transition.
  • Surfaces selected on appearance and slippery when wet.
  • Handrails added late and fixed into structure that was not detailed to take them.

Questions buyers ask

How long should a gangway be?

Long enough that the gradient at the worst water level is acceptable for the people using it. That makes it a site question, not a catalogue question — the water-level range drives the answer.

Do accessibility requirements apply to a private pontoon?

Accessibility obligations generally attach to public and passenger facilities rather than to private structures, but the applicable requirements depend on the facility and the jurisdiction. Where there is any public or commercial use, confirm the position with the approval authority.

Mean spring tidal range at Queensland standard ports

Heights above Queensland Port Datum (LAT 1992). Bars span mean low water springs to mean high water springs.

0 m1 m2 m3 m4 m5 m6 mGold Coast Seaway: low water springs 0.16 m, high water springs 1.47 m, range 1.31 mGold Coast Seaway1.31Mooloolaba: low water springs 0.3 m, high water springs 1.7 m, range 1.4 mMooloolaba1.40Cooktown: low water springs 0.75 m, high water springs 2.45 m, range 1.7 mCooktown1.70Brisbane Bar: low water springs 0.42 m, high water springs 2.22 m, range 1.8 mBrisbane Bar1.80Mourilyan Harbour: low water springs 0.88 m, high water springs 2.71 m, range 1.83 mMourilyan Harbour1.83Cairns: low water springs 0.82 m, high water springs 2.67 m, range 1.85 mCairns1.85Bowen: low water springs 0.73 m, high water springs 2.88 m, range 2.15 mBowen2.15Lucinda (Offshore): low water springs 0.85 m, high water springs 3.04 m, range 2.19 mLucinda (Offshore)2.19Weipa (Humbug Point): low water springs 0.77 m, high water springs 3.01 m, range 2.24 mWeipa (Humbug Point)2.24Bundaberg (Burnett Heads): low water springs 0.61 m, high water springs 2.94 m, range 2.33 mBundaberg (Burnett Heads)2.33Townsville: low water springs 0.83 m, high water springs 3.17 m, range 2.34 mTownsville2.34Shute Harbour: low water springs 0.58 m, high water springs 3.35 m, range 2.77 mShute Harbour2.77Urangan: low water springs 0.73 m, high water springs 3.54 m, range 2.81 mUrangan2.81Gladstone: low water springs 0.77 m, high water springs 4.01 m, range 3.24 mGladstone3.24Karumba: low water springs 0.42 m, high water springs 3.91 m, range 3.49 mKarumba3.49Rosslyn Bay: low water springs 0.67 m, high water springs 4.28 m, range 3.61 mRosslyn Bay3.61Port Alma: low water springs 0.93 m, high water springs 4.98 m, range 4.05 mPort Alma4.05Mackay Outer Harbour: low water springs 0.79 m, high water springs 5.35 m, range 4.56 mMackay Outer Harbour4.56Hay Point: low water springs 0.99 m, high water springs 5.86 m, range 4.87 mHay Point4.87Height above Queensland Port Datum (LAT 1992) — bar spans MLWS to MHWS
Show the data
PortMLWS (m)MHWS (m)Spring range (m)HAT (m)
Gold Coast Seaway0.161.471.311.97
Mooloolaba0.301.701.402.21
Cooktown0.752.451.703.28
Brisbane Bar0.422.221.802.78
Mourilyan Harbour0.882.711.833.58
Cairns0.822.671.853.57
Bowen0.732.882.153.77
Lucinda (Offshore)0.853.042.194.06
Weipa (Humbug Point)0.773.012.243.33
Bundaberg (Burnett Heads)0.612.942.333.68
Townsville0.833.172.344.22
Shute Harbour0.583.352.774.39
Urangan0.733.542.814.33
Gladstone0.774.013.244.87
Karumba0.423.913.494.85
Rosslyn Bay0.674.283.615.21
Port Alma0.934.984.055.96
Mackay Outer Harbour0.795.354.566.62
Hay Point0.995.864.877.18
A gangway that is comfortable at Gold Coast Seaway is solving a 1.31 m problem. The same gangway at Hay Point is solving a 4.87 m one — which is why gradient has to be checked against the range at your site, not a national average.Source: Maritime Safety Queensland — Semidiurnal Tidal Planes 2024. Tidal Datum Epoch 2010–2029. 264 locations published; 19 standard ports shown. Retrieved 2026-09-12.