A road is a thoroughfare, route, or way on land between two places that has been paved or otherwise improved to allow travel by foot or by some form of conveyance.
A road surface, or pavement, is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled roads and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently-used roads. Unmetalled roads, also known as gravel roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is acceleration in a fixed coordinate system. For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity, straight upwards of g ≈ 9.81 m/s2. By contrast, accelerometers in free fall will measure zero.
A dipstick is one of several measurement devices.
A falling weight deflectometer (FWD) is a testing device used by civil engineers to evaluate the physical properties of pavement in highways, local roads, airport pavements, harbor areas, railway tracks and elsewhere. The data acquired from FWDs is primarily used to estimate pavement structural capacity, to facilitate overlay design or determine if a pavement is being overloaded. Depending on its design, a FWD may be contained within a towable trailer or it may be built into a self-propelled vehicle such as a truck or van. Comprehensive road survey vehicles typically consist of a FWD mounted on a heavy truck together with a ground-penetrating radar and impact attenuator.
Weigh-in-motion or weighing-in-motion (WIM) devices are designed to capture and record the axle weights and gross vehicle weights as vehicles drive over a measurement site. Unlike static scales, WIM systems are capable of measuring vehicles traveling at a reduced or normal traffic speed and do not require the vehicle to come to a stop. This makes the weighing process more efficient, and, in the case of commercial vehicles, allows for trucks under the weight limit to bypass static scales or inspection.
Surface metrology is the measurement of small-scale features on surfaces, and is a branch of metrology. Surface primary form, surface fractality and surface roughness are the parameters most commonly associated with the field. It is important to many disciplines and is mostly known for the machining of precision parts and assemblies which contain mating surfaces or which must operate with high internal pressures.
A profilometer is a measuring instrument used to measure a surface's profile, in order to quantify its roughness. Critical dimensions as step, curvature, flatness are computed from the surface topography.
The AASHO Road Test was a series of experiments carried out by the American Association of State Highway and Transportation Officials (AASHTO), to determine how traffic contributed to the deterioration of highway pavements. Officially, the Road Test was "...to study the performance of pavement structures of known thickness under moving loads of known magnitude and frequency." This study, carried out in the late 1950s in Ottawa, Illinois, is frequently quoted as a primary source of experimental data when vehicle wear to highways is considered, for the purposes of road design, vehicle taxation and costing.
The Pavement Condition Index (PCI) is a numerical index between 0 and 100, which is used to indicate the general condition of a pavement section. The PCI is widely used in transportation civil engineering and asset management, and many municipalities use it to measure the performance of their road infrastructure and their levels of service. It is a statistical measure and requires manual survey of the pavement. This index was originally developed by the United States Army Corps of Engineers, but later it was standardized by the ASTM. The surveying processes and calculation methods have been documented and standardized by ASTM for both roads and airport pavements:
Geotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions. This type of investigation is called a site investigation. Additionally, geotechnical investigations are also used to measure the thermal resistivity of soils or backfill materials required for underground transmission lines, oil and gas pipelines, radioactive waste disposal, and solar thermal storage facilities. A geotechnical investigation will include surface exploration and subsurface exploration of a site. Sometimes, geophysical methods are used to obtain data about sites. Subsurface exploration usually involves soil sampling and laboratory tests of the soil samples retrieved.
ISO 25178: Geometric Product Specifications (GPS) – Surface texture: areal is an International Organisation for Standardisation collection of international standards relating to the analysis of 3D areal surface texture.
Road slipperiness is a condition of low skid resistance due to insufficient road friction. It is a result of snow, ice, water, loose material and the texture of the road surface on the traction produced by the wheels of a vehicle.
Pavement management is the process of planning the maintenance and repair of a network of roadways or other paved facilities in order to optimize pavement conditions over the entire network.
Road surface textures are deviations from a planar and smooth surface, affecting the vehicle/tyre interaction. Pavement texture is divided into: microtexture with wavelengths from 0 mm to 0.5 millimetres (0.020 in), macrotexture with wavelengths from 0.5 millimetres (0.020 in) to 50 millimetres (2.0 in) and megatexture with wavelengths from 50 millimetres (2.0 in) to 500 millimetres (20 in).
Crocodile cracking, also called alligator cracking and perhaps misleadingly fatigue cracking, is a common type of distress in asphalt pavement. The following is more closely related to fatigue cracking which is characterized by interconnecting or interlaced cracking in the asphalt layer resembling the hide of a crocodile. Cell sizes can vary in size up to 11.80 inches (300 mm) across, but are typically less than 5.90 inches (150 mm) across. Fatigue cracking is generally a loading failure, but numerous factors can contribute to it. It is often a sign of sub-base failure, poor drainage, or repeated over-loadings. It is important to prevent fatigue cracking, and repair as soon as possible, as advanced cases can be very costly to repair and can lead to formation of potholes or premature pavement failure.
Bleeding or flushing is shiny, black surface film of asphalt on the road surface caused by upward movement of asphalt in the pavement surface. Common causes of bleeding are too much asphalt in asphalt concrete, hot weather, low space air void content and quality of asphalt. Bleeding is a safety concern since it results in a very smooth surface, without the texture required to prevent hydroplaning. Road performance measures such as IRI cannot capture the existence of bleeding as it does not increase the surface roughness. But other performance measures such as PCI do include bleeding.
The Hermes Road Measurement System is the result of the EU-funded project Innovative, Highly Efficient Road Surface Measurement and Control System that was undertaken between August 2012 and July 2014. The project was funded through the European Union's Seventh Framework Capacities Programme that aimed at supporting research for the benefit of small-to-medium enterprises (SMEs). This is realised by cooperation between a group of SMEs from several European countries, working in collaboration with a number of research and technological development (RTD) institutes, collectively constituting the project's consortium.
Pavement performance modeling or pavement deterioration modeling is the study of pavement deterioration throughout its life-cycle. The health of pavement is assessed using different performance indicators. Some of the most well-known performance indicators are Pavement Condition Index (PCI), International Roughness Index (IRI) and Present Serviceability Index (PSI), but sometimes a single distress such as rutting or the extent of crack is used. Among the most frequently used methods for pavement performance modeling are mechanistic models, mechanistic-empirical models, survival curves and Markov models. Recently, machine learning algorithms have been used for this purpose as well. Most studies on pavement performance modeling are based on IRI.
The rolling straight-edge is an instrument used to measure the surface regularity of roads and similar structures such as airport runways. It consists of a straightedge of a fixed distance mounted on wheels with a sensor at the centrepoint measuring deviation in height. It is rolled along the road surface and set to specific trigger levels which can be logged automatically or by means of an audible alarm. The rolling straight-edge was developed by the British Road Research Laboratory to replace earlier manual methods of measurement using rulers. It has been used by several countries and remains in use in the United Kingdom, Germany and Taiwan.
