Airport pavement roughness evaluation based on cockpit and center of gravity vertical accelerations

Abstract

Rough pavements are generally responsible for vertical accelerations (VA) that can affect the aircraft, increase stopping distance and difficult to read the cockpit instrumentation. The International Roughness Index (IRI) and the Boeing Bump Index (BBI) are currently used to quantify airport pavement roughness and to identify sections that require maintenance and rehabilitation (M&R) activities. However, these indices were developed only based on dynamic responses of an automobile at 80 km/h to the irregularities of road pavements, and on physical characteristics of the irregularities (bump length and height), respectively, without considering the effect of aircraft VA. Additionally, current critical limits, suggested by Sayers & Karamihas and ANAC, for IRI (2.0 and 2.5 m/km, respectively) and by FAA for BBI (1.0) can misjudge the real condition of the pavement. This paper evaluates the effect of airport pavement roughness on VA at the aircraft cockpit (VACP) and at the center of gravity (VACG). The ProFAA software was used to compute both indices and to simulate VA in 4 representative aircraft traversing 20 runway profiles at 10 operational speeds varying from 37 to 370 km/h. Statistical comparisons and regression analyses were carried out. Principal results show that VACP is 50% higher than VACG and that exceeds the critical limit of 0.40 g when the IRI and BBI are higher than 3.7 m/km and 0.20, correspondingly. A case study is also presented to compare these limits and shows that decision-making based on IRI and VA can bring significant differences in the number of M&R activities.

Keywords

• Airport pavements
• Pavement roughness
• Vertical accelerations
• International roughness index
• Boeing bump index.