As part of the traffic control plan, road markings form the traffic surface and provide visual guidance for road users. Since their first application to the present day, road markings have become a common element of road infrastructure and one of the basic low-cost safety measures. The aim of this paper is to provide a systematic review of the most significant academic activities to date regarding the influence of longitudinal and transverse road markings as well as road markings for hazard locations (curves, intersections, and rural-urban transitions) on driver’s behaviour and overall road safety. The review includes a total of 71 studies from which are 52 peer-reviewed journal studies, 4 conference proceedings, and 15 professional reports. The studies are, based on their aim, divided into two categories: (1) studies on the impact of road markings on driver behaviour (36 studies) and (2) studies on the impact of road markings on road safety (35 studies).

Estimation of vehicular emissions at network level is a prominent issue in transportation planning and management of urban areas. For large networks, macroscopic emission models are preferred because of their simplicity. However, these models do not consider traffic flow dynamics that significantly affect emissions production. This study proposes a network-level emission modeling framework based on the network-wide fundamental diagram (NFD), via integrating the NFD properties with an existing microscopic emission model. The NFD and microscopic emission models are estimated using microscopic and mesoscopic traffic simulation tools at different scales for various traffic compositions. The major contribution is to consider heterogeneous vehicle types with different emission generation rates in a network-level model. This framework is applied to the large-scale network of Chicago as well as its central business district. Non-linear and support vector regression models are developed using simulated trajectory data of 13 simulated scenarios. The results show a satisfactory calibration and successful validation with acceptable deviations from the underlying microscopic emissions model regardless of the simulation tool that is used to calibrate the network-level emissions model. The microscopic traffic simulation is appropriate for smaller networks, while mesoscopic traffic simulation is a proper means to calibrate models for larger networks. The proposed model is also used to demonstrate the relationship between macroscopic emissions and flow characteristics in the form of a network emissions diagram. The results of this study provide a tool for planners to analyze vehicular emissions in real time and find optimal policies to control the level of emissions in large cities.

Alternative intersection designs can offer safety and operational benefits with potentially lower costs than conventional intersections when implemented in the proper setting. The Federal Highway Administration has previously identified a subset of alternative designs called reduced left-turn conflict intersections as a proven safety countermeasure. Median U-turn intersections (also known as “Michigan lefts” or “boulevard turnarounds”) are one such design that accommodates all left-turn movements via directional U-turn crossovers within the median. Prior work has consistently shown that median U-turn intersections can provide superior safety performance when used in the appropriate conditions. However, research that is specific to unsignalized reduced left-turn conflict intersections continues to be limited to work conducted before the Highway Safety Manual, or which includes restricted crossing U-turn intersections. This study included the evaluation of historical traffic crashes and volume data at 95 unsignalized intersections in the state of Michigan. This included the collection of data for 39 median U-turn sites and 56 reference group sites to estimate safety performance functions and crash modification factors that can be used when considering future conversions. Ultimately, crash modification factors for fatal and injury crashes of 0.438 and 0.686 are recommended when converting intersections with undivided two-lane two-way major approaches and four-lane divided boulevard major approaches, respectively. Although there was no significant difference in property damage only crashes associated with converting intersections with undivided, two-lane, two-way major approaches, a crash modification factor of 1.325 is recommended for property damage only crashes specific to conversions with four-lane, divided boulevard major approaches.