**1. Introduction**

Evaluation of pavement condition is one of the major elements of any pavement maintenance managemen<sup>t</sup> system (PMMS). Through pavement condition, maintenance needs, budget, and priority are determined. Pavement condition usually involves distress surveys, roughness and structural capacities, and skid resistance. Most, if not all highway agencies incorporate at least one of these components [1].

There are two levels of pavement evaluation: network level and project level. Network level evaluation gives us a comprehensive overview of the network's condition. In project level evaluation, detailed information on pavement conditions are determined.

Riyadh city and through Riyadh Municipality, and the General Directorate for Maintenance and Operation, have been implementing PMMS utilizing visual condition surveys, roughness measurements, structural capacities, and skid resistance to evaluate pavement condition. Visual checks and pavement roughness are usually performed annually on the street network. Pavement skid resistance is conducted annually on only main streets. Evaluation of structure is only performed at a project-level and is based on manual and roughness evaluation results [2].

In general, visual condition surveys include analyzing the distress type, as well as its severity level, extent, and site. As there are various authorities involved, there are many techniques for conducting pavement condition surveys. The city of Riyadh has its pavement

**Citation:** Al-Mansour, A.I.; Shokri, A.A. Correlation of Pavement Distress and Roughness Measurement. *Appl. Sci.* **2022**, *12*, 3748. https://doi.org/10.3390/ app12083748

Academic Editors: Amir Tabakovic, Jan Valentin and Liang He

Received: 5 March 2022 Accepted: 2 April 2022 Published: 8 April 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors.Licensee MDPI, Basel, Switzerland.This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

inspection procedure. As part of the procedure, a local pavement condition evaluation called the Urban Distress Index (UDI) should be established. The index is scaled from 0 to 100, with 100 representing excellent pavement condition. The UDI values are determined by visual assessment of the type, severity, and extent of pavement distress. Typically, an investigator is sent to a specific section of pavement in order to gather the necessary distress data to report the current types, severity levels, and quantities of distress. The data is gathered by physically walking through the segment. The process delivers specific information regarding the state of each segmen<sup>t</sup> of pavement. Furthermore, due to the large size of the city's pavement network, the process is both time-consuming and expensive.

Road pavement surface roughness is generally used to assess the riding condition of a road pavement surface. It is closely linked to the serviceability of pavement, which is a measurement of the pavement's physical characteristics. Profilometric, vehicle response, and subjective evaluation are the three types of roughness measurement techniques currently in use. The most accurate and well-suited for detailed analysis are profilometric techniques.

Riyadh PMMS uses the profilometric method to measure pavement roughness. The International Roughness Index (IRI) is used to calculate roughness measures. The IRI and the road profile are computed at regular intervals and are both shown on the computer. The horizontal and vertical profile data obtained from the profilometric method are converted into a response of the vehicle's motion by utilizing the technique of IRI calculation, which is predicated by a mathematical model. The IRI value is calculated by dividing the displacement units by the length units. At speeds of (40–50) kilometers per hour, roughness measurements are taken. Due to this, roughness measurements were acquired in a reasonably short period of time and at a cheap cost.

The major goal of this study is to determine the relationship between pavement distress assessment and roughness measures in the Riyadh roadway network. The pavement distresses were ride quality-related distresses such as cracking, patching, potholes, depression, rutting, and raveling.

Roughness measurements are indicated by the International Roughness Index (IRI). The analysis included establishing correlation factors between the distress types of riding quality and IRI and developing models to forecast the pavement distress type values based on IRI and highway class.

### **2. Literature Review**
