Tunnel lay-by spacing is directly related to traffic safety and engineering investment. Nevertheless, its mechanism is not clear, and the rationality of the exiting norms with respect to tunnel lay-by spacing needs to demonstrate. A calculation model for tunnel lay-by spacing was derived by considering the headway and the physical kinematics of the two vehicles chasing and encountering. With it, the influence of various parameters on lay-by spacing were analysed and the rationality of the model were discussed through comparing with existing norms. Results shows longitudinal gradient rate, daily average traffic flow, rolling resistance coefficient, posted speed limit are significant to determine the lay-by spacing, and the most important parameter is longitudinal gradient rate. Existing tunnel lay-by spacing norm values are not reasonable enough, either too strict or too loose. These findings provide scientific support for how to select tunnel lay-by spacing value, which can improve tunnel traffic safety and make engineering investment reasonable.

The aim of the article is indicating the advantages of utilizing the synergy obtained by introducing two management methods: Lean Construction and Agile Management using the example of the process of deliveries of concrete mix in road construction. Despite the seemingly contradictory assumptions (Lean Management aims at limiting wastefulness and maximizing the value for the customer and agile management serves for creating the possibility for fast, effective response to non-expected changes thanks to the adopted strategy of flexibility, which usually requires engaging additional resources), both management methods deliver the effect of increasing the effectiveness of the machine laying the pavement. Using a “spaghetti diagram” (one of the tools of Lean Management) led to limiting the time losses during loading and unloading the concrete mix destined for constructing highway pavement. On the other hand, the tactic of technological flexibility in the form of a modification of the concrete mix allowed for broadening the time frame for the delivery of concrete to the construction site to as much as two hours. Moreover, applying the real time delivery management system (in accordance with the assumptions of Construction 4.0) created the possibilities for ensuring quick reacting to the changing conditions of delivery and laying the concrete mix in the pavement and ensuring the appropriate functioning of the machine laying the pavement. The presented examples indicated the advantages of the suggested concept in reference to the traditional solution.

Based on the test and observation of the desert hinterland wind field, combined with the numerical simulation of Fluent wind-sand two-phase flow, the sand resistance performances of comprehensive protection in the desert hinterland under strong wind environment are researched. The transient wind speed and wind direction around the comprehensive protection facility are measured by two 3D ultrasonic anemometers on the highway in the desert hinterland, and the initial wind speed of the sand flow is provided for the numerical simulation boundary. The sedimentary sand particles around the comprehensive protection facility are collected for particle size analysis, and the particle size distributions of sedimentary sand particles at different locations are obtained. Numerical models of high vertical sand barriers, grass checkered sand barriers and roadbeds are established by Fluent, the wind-sand flow structures around the comprehensive protection facilities and desert hinterland highway under the strong wind environment are obtained, and the influence laws of the comprehensive protection facilities on the movement of wind-sand flow and sand deposition characteristics are obtained. The study found that the comprehensive protection facilities disturbed the wind and sand flow, and there are significant airflow partitions around the comprehensive protection facilities. The wind speed decreases rapidly after the wind-sand flows through the high vertical sand barrier; the wind-sand flow rises at the end of the high vertical sand barrier. When the wind-sand flow moves around the grass checkered sand barrier, the wind speed has dropped to the range of 0–3 m/s, and the wind speed near the ground by the grass checkered sand barrier is further reduced. Due to the existence of the concave surface of the grass grid, there are small vortices inside the grass grid sand barrier. Large sand particles are mainly deposited on the windward side and inside of high vertical sand barriers. The grass checkered sand barrier forms a stable concave surface to generate backflow, which can ensure that the sand surface does not sand itself in a strong wind environment, and can also make a small amount of sand carried in the airflow accumulate around the groove of the grass checkered sand barrier. The numerical simulation results are consistent with the measured results, and the comprehensive protection measures have achieved good sand control effects.

The durability of roads is dependent on the proper screening of the variations in subsurface geological characteristics and conditions through geo-engineering investigations and good construction practices. In this study, electrical resistivity tomography (ERT) technique was used to investigate the subsurface defects and potential failures along the substrate of Etioro-Akoko highway, Ondo State, southwestern Nigeria. Results of the inverse model resistivity sections generated for the two investigated traverses showed four distinct subsurface layers. The shallow clayey topsoil, weathered layer, and partially weathered/fractured bedrock have resistivity values ranging from 4–150 ohm-m, 10–325 ohm-m, and 205–800 ohm-m, with thickness values of 0–2 m, 0.5–12.5 m, and less than few meters to > 24 m, respectively. The fresh bedrock is characterised by resistivity generally in excess of 1000 ohm-m. The bedrock mirrored gently to rapidly oscillating bedrock troughs and relatively inclined deep penetrating multiple fractures: F1–F’1, F2–F’2 and F3–F’3, with floater in-between the first two fractures. These delineated subsurface characteristic features were envisaged as potential threats to the pavement of the highway. Pavement failures in the area could be attributed to the incompetent clayey sub-base/substrate materials and the imposed stresses on the low load-bearing fractured bedrock and deep weathered troughs by heavy traffics. Anticipatory construction designs that included the use of competent sub-base materials and bridges for the failed segments and fractured zones along the highway, respectively, were recommended.

Inaccurate estimation in highway projects represents a major problem facing planners and estimators, especially when data and information about the projects are not available, and therefore the need to use modern technologies that addresses the problem of inaccuracy of estimation arises. The current methods and techniques used to estimate earned value indexes in Iraq are weak and inefficient. In addition, there is a need to adopt new and advanced technologies to estimate earned value indexes that are fast, accurate and flexible to use. The main objective of this research is to use an advanced method known as artificial neural networks to estimate the TSPI of highway buildings. The application of artificial neural networks as a new digital technology in the construction industrial in Republic of Iraq is absolutely necessary to ensure successful project management. One model built to predict the TCSPI of highway projects. In this current study, artificial neural network model were used to model the process of estimating earned value indexes, and several cases related to the construction of artificial neural networks have been studied, including network architecture and internal factors and the extent of their impact on the performance of artificial neural network models. Easy equation was developed to calculate that TSPI. It was found that these networks have the ability to predict the TSPI of highway projects with a very outstanding saucepan of reliability (97.00%), and the accounting coefficients (R) (95.43%).