Effects of Variation in Quarter-Car Simulation Speed on International Roughness Index Algorithm

Abstract

The international roughness index (IRI) is widely used throughout the world as a measure of road roughness. A quarter-car simulation at 80 km/h is performed on the longitudinal profile to compute IRI. Questions have been raised regarding the applicability of IRI for roads that are used at speeds above or below this simulation speed. To gain more insight into the effects of simulation speed, an investigation was carried out to determine how the roughness computed from the IRI model changes for different simulation speeds of the quarter car. This investigation was performed on an asphalt concrete data set and a jointed portland cement concrete data set. For simulation speeds between 60 and 110 km/h, the response from the IRI model was within ±0.20 m/km of the IRI for 80% of the asphalt sections and 61 % of the concrete sections used in the study. Although the output from the quarter-car model for the different simulation speeds was different from the IRI (simulation speed of 80 km/h), it is unclear to what extent a user's perception of the roughness of a roadway changes with the speed of travel. If examples of roadways are found where the subjective opinion of roadway users of the roughness seems inconsistent with the IRI, it is recommended that the IRI model be used with the current speed limit of the roadway to examine whether the obtained output provides a better match with the opinion expressed by roadway users.

The Impact of Road Roughness on the Duration of Contact Between a Vehicle Wheel and Road Surface

“…Analysis of the influence made by simulation speed on the variation of IRI value was performed (Perera, Kohn 2004). For simulation speed less than 80 km/h, identified IRI values showed wider scatter than for greater simulation speed.…”

Integrating Pavement Sensing Data for Pavement Condition Evaluation

“…The presence of surface vertical irregularities and profile elevations along a pavement’s longitudinal line contributes to what is defined as pavement roughness ( Figure 1 ). Roughness is responsible for a vehicle’s suspension response while it moves over the road [ 32 ]. IRI calculations are based on the dynamic response of a reference automobile, the so-called Quarter-Car System (QCS) [ 3 , 5 , 32 , 33 ].…”

“…Roughness is responsible for a vehicle’s suspension response while it moves over the road [ 32 ]. IRI calculations are based on the dynamic response of a reference automobile, the so-called Quarter-Car System (QCS) [ 3 , 5 , 32 , 33 ]. The model simulates a QCS travelling at a constant speed of 80 km/h and measures the suspension deflection.…”

Research and Evaluation of Ruts in the Asphalt Pavement on Lithuanian Highways

“…The performed analysis shows that ruts on the asphalt pavement are formed by heavy vehicles (Perera, Kohn 2004), and, because of their large and frequently changing depth, mainly suffer fast travelling private cars. Therefore, not only the average rut depth is important but also its variation causing the driver surprise and confusion effect.…”