Evaluating the use of low-cost technologies for pavement surface evaluations

Date
2020-12
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: iAbstractSouth Africa has the tenth largest road network in the world,with a total road network of 750 000 kilometres. The Provincial governmentsareresponsible for the regional roads, while local municipalities are responsible for localroadsand city streets. Both these management authorities monitor road conditions through a time-consuming visual inspection and reporting process as perthe TMH 9 manual.Current road surface inspection methods used by the South African provincial governments include a two-phase visual inspection. This method can be time-consuming,resulting in increased inspection and maintenance costs. Visual inspections rely on the trained perspective of the assessor. This may lead to inconsistencies between assessors or inspections.Provincial governments in South Africa perform the routine surface inspections on an annual basis which result in high ongoing costs of pavement surface inspections. Alternative pavement inspection methods with low-cost hardware could, therefore, reduce the cost of pavement surface inspections and improve data accuracyand safety. This thesis evaluatesdifferent inspection platforms based on theirtime,cost and qualityperformance. The three platforms evaluated include traditional inspection methods (TMH 9), as well as UAV platforms and ground-basedvehicle platforms fitted with different low-cost technologytypes. The investigated technology types includea digital camera, thermal device and LIDARdevice.The evaluation includesthe testing of technology types and vehicle platforms to determine thedata collection speed limit, the ability of the technology to capture different crackwidths andthe sensitivity to changing light conditions.The testing highlighted that the digital camera required additional lighting to reduce the sensitivity to changing light conditions. The required inspection time dependsonthe maximum platform travel speed untilone image pixel becomes blurry.The image blurdepends on the shutter speed, field of view, height above the pavement surface and the time-lapse speed of the device. It was determined at two meters above the pavement surface,that thethermal SeekShotPro (9Hz) can collect data at 68km/h compared to 19.5km/h forthe GoPro Hero 8 digital camera. The total cost includesvariable costssuch as the operator cost, vehicle running cost and exchange rate.AMonte Carlo analysis wasfollowed to determine the most probable cost for each platformand technology typebased on different distribution models developed for the cost evaluation. Thermal devices fitted to the different platforms resulted in a lower operating cost for each platform. It was found that theUAV platform hasthe lowest operating cost,followed by a ground-based vehicle platform and the traditional inspection method.The quality of each platform ismeasured via a comparison ofthe pavement assessment list provided in the TRH 22 manual.The ability of each technology type to identify different distress mechanisms depended on the ability to measure distance and identify different crack widths accurately. It was determined that the thermal devicecould identify 73.03% of the different distress mechanisms, while the digital camera and LIDARdevice could identify 68.54% and 38.58% respectively. Ultimately the ground-based vehicle platform fitted with a combination of a thermal and LIDARdevice proved to be the most suitable for pavement surface evaluations. Using a combination of deviceswill increase the numberofdifferentdistress mechanisms identified to 86.14%.
AFRIKAANSE OPSOMMING: Suid Afrika het die tiende langste pad netwerk in die wêreld met ‘n totale pad netwerk van 750000 kilometer. Die provinsiale regering is verantwoordelik vir die provinsiale en streeks paaie terwyl die plaaslike munisipaliteit verantwoordelik is vir die stedelike paaie. Beide hierdie entiteite monitor plaveisel kondisies met ‘n tydsame visuele inspeksie proses soos voorgeskryf in TMH 9. Huidige plaveisel inspeksie metodeswat deur die Suid-Afrikaanse provinsiale regerings gebruikword, sluit 'n twee-fase visuele inspeksie in. Hierdie metode kan tydrowend wees, wat lei tot verhoogde inspeksie-en onderhoudskostes. Beidehierdievisuele inspeksies maak staat op die opgeleide perspektief van die assessor. Dit kan moontlik lei tot teenstrydighede tussen assessore of inspeksies. Provinsiale regerings in Suid-Afrika voer jaarliks die roetineplaveisel inspeksies uit, wat hoëplaveisel inspeksiekostestot gevolg het. Alternatiewe plaveisel inspeksiemetodes met lae-kostetegnologiekan dus die koste van plaveisel inspeksiesverlaag en die akkuraatheid van inspeksiesverbeter. Hierdie tesis het verskillende inspeksieplatforms geëvalueer volgenshultyd, koste en kwaliteit. Die drie platforms wat geëvalueer word, sluit in tradisionele inspeksiemetodes (TMH 9), UAV-platforms en grondgebaseerde voertuigplatforms wat met verskillende lae-kostetegnologieëtoegerus is. Die tegnologietipes het 'n digitale kamera, termiese toestel en LIDAR-apparaat ingesluit.Die evaluering sluit die toets van tegnologie-soorte en voertuigplatforms in om die spoed van data-insameling te bepaal, die vermoë van die tegnologie om verskillende kraak wydteste identifiseeren die sensitiwiteit vir veranderende lig toestandete bepaal. Die toetsehet gewys dat die digitale kamera addisionelebeligting benodig om die sensitiwiteit vir veranderende lig toestande te verminder. Dietotale inspeksietyd hangaf van die maksimum spoedwanneer een pixelvaag word. Die maksimum spoed word beïnvloed deurdie sluiterspoedvan die toestel, die sigwydtevan die toestel, die hoogte van die toestel bo die plaveisel oppervlak en die tydsverlooptussen foto’svan die toestel. Dit is bepaal dat optwee meter bokant die sypaadjie kan die termiese SeekShot Pro (9Hz) data teen 68 km/h versamel in vergelyking met 19.5 km/hvan die GoProHero 8 digitale kamera. Die koste evaluering sluit veranderlike kostessoos die operateur koste, lopende voertuig koste en wissel koers in.'n Monte Carlo-analise is gevolg om diemeeswaarskynlike koste vir elke platform en tegnologietipe te bepaal, gebaseer op verskillende verspreidingsmodelle wat ontwikkel is vir hierdie tesis. Die tesis vind dat termiese toestelle wat op die verskillende platforms gemonteer word het gelei tot 'n laer bedryfskoste vir elke platform. Die UAV-platform het die laagste bedryfskoste gevolg deur 'n grond voertuigplatformen die tradisionele inspeksie metode.Die kwaliteit van elke platform word gemeet aan die lys van plaveisel inspeksieswat in die TRH 22-handleiding voorsien word. Die vermoë van elke tegnologie tipeom verskillende defekte te identifiseer, hang af van die vermoë om afstand akkuraat te meeten verskillende kraak wydteste identifiseer. Dit is bepaal dat die termiese toestel 73,03% van die verskillende defekteidentifiseer, terwyl die digitale kamera en die LIDAR-toestel onderskeidelik 68,54% en 38,58% identifiseer.‘nGrond voertuigplatformmet 'n kombinasie van 'n termiese en LIDAR-apparaat saldie geskikstewees vir die evaluering van plaveisel oppervlaktes. Dit sal die aantal verskillende defektewat geïdentifiseer kan word, verhoog na 86,14%.
Description
Thesis (MEng)--Stellenbosch University, 2020.
Keywords
Pavements -- Defects, Pavement Inspections -- Cost, UCTD, Pavements -- Testing -- Equipment and supplies, Pavements -- Surface defects
Citation