Acquiring Data for Highway Maintenance Using Fixed Terrestrial 3d Laser Scanning System

this research emphasis on using laser scan technology with high positional accuracy and high density automation for modeling the road surface. Surface modeling is essential for all road maintenance applications. Road flexible pavement distresses will be classified and summarized. Five major categories of flexible pavement road distresses will be considered in this study. The study deals with issues of road surveying, the safety of surveyors, data acquisition methodology, data processing, assessment, analysis and achieved accuracy. The used methodology in this paper allows accurate determination of paving material volumes that should be milled off the upper layer of the road surface and the volume of the filling material required to achieve a smooth road surface. However, the present work shows that using terrestrial laser scanning technologies for modeling the road surface has advantages such as surveying speed, big roads, highways and tunnels. Also it provides the safety for surveyors and the absence of a disruption to traffic. 1INTRODUCTION ne of the main transportation systems in Saudi Arabia is the road system, which is developed in rapid manner. The main function of these roads is to connect the cities, towns and villages throughout the kingdom. Therefore, it is required to have roads with excellent pavements from structural and functional point of views. In the last five plans of Saudi Arabia, the Ministry of Transportation (MOT) did perform many projects to establish solid and strong infrastructure of ways with cost in billions of riyals, and now it is considered as long term national investment. The ministry of planning statistics in Saudi Arabia stated that the kingdom paid more than 4000 billion riyals through 27 years. From this it can be noticed how huge the investment in the roads network is. The kingdom established giant roads networks. In the year 1372H O MOHAMMAD H. ALAWI C: 27 the network roads increased from 240 km to more than 187000 km in the year 1418H. [3]. Due to the increase of population, technology, travelling, education etc., the demand of transportation people and goods will increase. To keep these roads safe and durable, maintenance should be taken in consideration. Pavement distress such as rutting, cracking, aging, stripping, raveling etc. cause a lot of problems and lack of comfort for vehicles and passengers. Also it may cause accidents due to unexpected stopping of cars. Moreover, failed pavements require costly maintenance and repairs which in turn cause restrictions to traffic flow, thus causing undesirable traffic congestion. Some of the solutions of these distresses are a complete removal or partial removal of the bituminous layer. In this study terrestrial 3D laser scanners are used. It is popular and is increasingly used in providing as-built and modeling data in transportation applications, including land surveying, archaeological studies, architecture, bridge structures, and highway surveys. Unlike the traditional total station of only making a few measurements in a minute, the terrestrial laser scanner captures thousands of surface points (i.e. point cloud) instead. After making a series of distance measurement in uniform angular increments in both horizontal and vertical planes, the terrestrial laser scanner can provide a detailed portrait of the surface of the object. Laser scanners can reduce lane closures, decrease risk of injuries, and increase productivity. The resulting point cloud and detailed 3D model allows engineers to extract all the required data in the office, decreasing or eliminating the need for surveyors to return to the site for additional measurements. Laser scanning technology is very economical with faster information processing speed and automation procedures as well as the aspect of information precision compared to other technologies with the same purposes. Compared to existing techniques systems from the high rate-of-capture and density of three dimensional data, laser scanning technology is much better. The greatest difference between Laser scanning technology and photogrammetry is each technology adopts active sensor and passive sensor. Different sensors support different way of getting and processing information as well as the form of information. Laser scanning technology allows a large amount of three-dimensional data including colours and intensity information and their rapid process. Furthermore, the survey of existing ground profiles is of particular importance for the design, construction and on-going maintenance of the road network. Road closure for surveying ground profiles, in particular for the high speed roads, is costly, easy to attract public discontent and not easy to be approved by the Police and Transport Department. To overcome the difficulties and for safety sake, the terrestrial laser scanner that employing the “contact-free” laser scanning technology is considered as a useful supplementary surveying tool for getting the road profiles without the need of road closure. The purpose of this study is to make full use of laser scanning technology for road surface surveying and for more accurate geometric information extraction for the roads. Furthermore, the suitable solutions for road surface maintenance will be suggested and detailed. 2CLASSIFICATION OF ROAD DISTRESSES In this paper road flexible pavement distresses are classified using survey instruments, information about these distresses will be summarized. Five major categories of flexible pavement road distresses are considered in this research [1, 2, 9], as shown in Fig.1. Figure 1 S.H.R.P Asphalt concrete surfaced pavement distress types C: 28 MANSOURA ENGINEERING JOURNAL, (MEJ), VOL. 41, ISSUE 1, MARCH 2016 Distresses occur in flexible pavements, causes, method of repairing, level of the distresses are summarized as following: a) Cracking 1Alligator (fatigue) cracking: Is a series of interconnected cracks that have many sided sharp angled pieces. Usually less than one foot on longest side. Chicken wire/alligator pattern. Occurs only in areas subjected to repeated loading (usually in wheel paths). Initially appears as longitudinal cracks:  Causes: fatigue failure under repeated traffic, weak or thin surface  Repair/maintenance techniques: surface seal, overlay or reconstruction  Low: if little cracks found parallel and not connected to each other  Moderate: if the cracks connected to each other but not deep (still at the surface)  High: if the cracks are connected to each other, separated and deep 2Block cracking: Is a rectangular piece of asphalt surface ranging in size from approximately one square feet to 100 square feet:  Causes: daily air temperature cycle, shrinkage of asphalt pavement surface,  Repair/maintenance techniques: surface seal, recycle or overlay,  Low: un spalled cracks with a mean width less than 6 mm, cracks with sealant in a good condition  Moderate: cracks that are moderately spalled, cracks with a mean width varies from 6 t0 19 mm.  High: cracks that are severely spalled with a mean width greater than 19 mm. 3Edge cracking: Is a crescent shaped cracks or fairly continuous cracks parallel to, and usually within one to two feet of, the outer edge of pavement.  Causes: when paved shoulders do not exist.  Repair/maintenance techniques: seal crack, partial or full depth patch  Low: if the cracks have a mean width less than 6 mm,  Moderate: if the cracks have a mean width varies from 6 mm to 19mm,  High: if the cracks have a mean width greater than 19mm. 4Longitudinal cracking: Cracks are relatively parallel to pavement centreline:  Causes: daily air temperature cycle, hardening of asphalt, poor paving lane joint,  Repair/maintenance techniques: seal crack, partial or full depth patch,  Light: if the cracks have a width less than 6 mm,  Medium: if the cracks have a thickness widths varies from 6 t0 19 mm,  Heavy: if the cracks have thickness widths greater than 19mm. 5Reflection cracking at joints: Is a crack in asphalt concrete overlay surfaces over jointed concrete pavements at original joints. Knowing slab dimensions beneath surface helps identify these cracks.  Light: if the cracks have a width less than 6 mm,  Medium: if the cracks have a thickness widths varies from 6 t0 19 mm,  Heavy: if the cracks have thickness widths greater than 19mm. 6Transverse cracking: Is a crack relatively perpendicular to pavement centreline (not load associated).  Causes: daily air temperature cycle, hardening of asphalt, poor paving lane joint,  Repair/maintenance techniques: seal cracks, partial or full depth batch,  Low: if the cracks have a width less than 6 mm,  Moderate: if the cracks have a thickness widths varies from 6 t0 19 mm,  High: if the cracks have thickness widths greater than 19mm. b) Patching and potholes 1Patch/patch deterioration: is apportion of pavement surface that has been removed and replaced  Causes: utility cut.  Repair/maintenance techniques: replace patch area.  Low: patch is in very good condition or has low severity distress of any type.  Moderate: patch has moderate severity distress of any type.  High: patch has high severity distress of any type. 2Potholes: is bowlshaped holes of various sizes in the pavement surface.  Causes: poor drainage, weakness of pavement surface, sub base or sub grade, thin surface.  Repair/maintenance techniques: partial or full depth patch.  Low: if the hole has a depth less than 25 mm, and area varies from 0.304 square meter to 0.912 square meter  Moderate: if the hole has a depth varies from 25 to 50 mm and area varies from 0.304 square meter to 0.912 square meter MOHAMMAD H. ALAWI C: 29  High: if the hole has a depth greater than 50 mm, and area greater than 0.912 square meter c) Surface deformation 1Rutting: is a longitudinal surface depression in the wheel path.  Causes: inadequate compaction, improper design, consolidation or lateral movement under traffic, lo