The Challenges of Assessing Curved Ramps

19 May, 2024
Ensuring the safe, compliant and efficient movement of vehicles on curved ramp sections is not as easy as straight ramp sections. Curved ramps offer the extra complexity of longitudinal grades varying along any given cross-section, depending on the length and height between connecting sections.

To ensure vehicles can safely traverse these curved sections without scraping along the bottom or hitting any overhead obstructions, it’s important to apply traffic engineering principles in the assessment. Here’s how we apply our traffic engineering expertise to assess curved sections of ramps, within the context of residential/private car parks:

  • Calculating the actual grade of the inner and outer curve: This is done by first identifying the actual length the vehicle travels along the inside and outside of the curve. With the given height differences, we can calculate the actual grades and assess it in the context of the grades upstream and downstream of the ramp.
  • Vertical clearance assessment: We utilise specialised computer software to generate vertical clearance diagrams of a design vehicle – usually the B99 vehicle (99th percentile vehicle in size) – traversing along the longitudinal section of each calculated inner and outer ramp curve section. The output is a visual representation in which we can assess if sufficient ground clearances and height clearances are achieved. An example is provided in the figure below.
  • Assessing the crossfall (the slope of the ramp at right angles to the direction of travel): Using our ramp review calculator, we can input the RLs (elevation) along the given inner and outer curve lengths, and knowing the width, we can identify the maximum crossfall to ensure it’s in accordance with the relevant standards.

Vertical clearance assessment for a curved ramp

Limitations do exist without 3D modelling software, but these traffic engineering services generally provide sufficient analysis and consultation in the design of curved ramps, giving assurance to architects, developers, building contractors, local councils and end-users alike.

Written by Rico Kobelt

Written by Rico Kobelt

As a Traffic Engineer for Amber, I’m passionate about the opportunities I get to improve urban design and facilitate positive outcomes for communities. I’m a lifelong learner and enjoy utilising my background in sustainability and engineering to help improve safety and efficiency outcomes in the traffic and transport landscape.
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Amber Organisation acknowledges the Traditional Owners of Country throughout Australia and recognises the continuing connection to lands, waters and communities. We pay our respect to Aboriginal and Torres Strait Islander cultures; and to Elders past and present.

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