A roundabout is a type of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.
An intersection is an at-grade junction where two or more transport flows meet or cross. Intersections may be classified by number of road segments, traffic controls or lane design.
TRL Limited, trading as TRL is an independent private company offering a transport consultancy and research service to the public and private sector. Originally established in 1933 by the UK Government as the Road Research Laboratory (RRL), it was privatised in 1996. Its motto or tagline is 'The Future of Transport'.
A green wave occurs when a series of traffic lights are coordinated to allow continuous traffic flow over several intersections in one main direction.
Microsimulation is a category of computerized analytical tools that perform highly detailed analysis of activities such as highway traffic flowing through an intersection, financial transactions, or pathogens spreading disease through a population. Microsimulation is often used to evaluate the effects of proposed interventions before they are implemented in the real world. For example, a traffic microsimulation model could be used to evaluate the effectiveness of lengthening a turn lane at an intersection, and thus help decide whether it is worth spending money on actually lengthening the lane.
A junction is where two or more roads meet.
Intersection Capacity Utilization (ICU) method is a tool for measuring a roadway intersection's capacity. It is ideal for transportation planning applications such as roadway design, congestion management programs and traffic impact studies. It is not intended for traffic operations or signal timing design. ICU is also defined as "the sum of the ratios of approach volume divided by approach capacity for each leg of intersection which controls overall traffic signal timing plus an allowance for clearance times." The ICU tells how much reserve capacity is available or how much the intersection is overcapacity. The ICU does not predict delay, but it can be used to predict how often an intersection will experience congestion.
In traffic engineering, saturation describes the maximum traffic flow which can be handled by a junction. The saturation flow is the rate at which a continuous flow of vehicles can pass through a constant green signal, typically expressed in vehicles per hour or PCUs per hour.
The normal function of traffic lights requires more than sight control and coordination to ensure that traffic and pedestrians move as smoothly, and safely as possible. A variety of different control systems are used to accomplish this, ranging from simple clockwork mechanisms to sophisticated computerized control and coordination systems that self-adjust to minimize delay to people using the junction.
The Canadian Capacity Guide for Signalized Intersections (CCG) is a publication of the Canadian Institute of Transportation Engineers (CITE). It provides a methodology that allows Traffic Engineers to plan, design, and evaluate traffic signal controlled roadway intersections.
Traffic simulation or the simulation of transportation systems is the mathematical modeling of transportation systems through the application of computer software to better help plan, design, and operate transportation systems. Simulation of transportation systems started over forty years ago, and is an important area of discipline in traffic engineering and transportation planning today. Various national and local transportation agencies, academic institutions and consulting firms use simulation to aid in their management of transportation networks.
Paramics is traffic microsimulation software, originally developed by Quadstone Ltd. There is a related pedestrian microsimulation product called the Urban Analytics Framework.
Cell Transmission Model (CTM) is a popular numerical method proposed by Carlos Daganzo to solve the kinematic wave equation. Lebacque later showed that CTM is the first order discrete Godunov approximation.
TRANSYT-7F is a traffic simulation and signal timing optimization program. The primary application of TRANSYT-7F is signal timing design and optimization. TRANSYT-7F features genetic algorithm optimization of cycle length, phasing sequence, splits, and offsets. TRANSYT-7F combines a detailed optimization process with a detailed macroscopic simulation model.
TSIS-CORSIM is a microscopic traffic simulation software package for signal systems, highway systems, freeway systems, or combined signal, highway and freeway systems. CORSIM consists of an integrated set of two microscopic simulation models that represent the entire traffic environment. NETSIM represents traffic on urban streets. FRESIM represents traffic on highways and freeways. Microscopic simulation models the movements of individual vehicles, which include the influences of geometric conditions, control conditions, and driver behavior. TSIS is an integrated development environment that enables users to conduct traffic operations analysis. Built using a component architecture, TSIS allows the user to customize the set of included tools, define and manage traffic analysis projects, define traffic networks and create inputs for traffic simulation analysis, execute traffic simulation models, and interpret the results of those models.
Adaptive traffic control system (ATCS) is a traffic management strategy in which traffic signal timing changes, or adapts, based on actual traffic demand. This is accomplished using an adaptive traffic control system consisting of both hardware and software.
Sidra Intersection is a software package used for intersection (junction) and network capacity, level of service and performance analysis, and signalised intersection and network timing calculations by traffic design, operations and planning professionals.
Split Cycle Offset Optimisation Technique (SCOOT) is a real time adaptive traffic control system for the coordination and control of traffic signals across an urban road network. Originally developed by the Transport Research Laboratory for the Department of Transport in 1980, research and development of SCOOT has continued to present day. SCOOT is used extensively throughout the United Kingdom as well as in other countries.
Junctions is a software package by Transport Research Laboratory. It incorporates the previously separate programs ARCADY, PICADY and OSCADY. The latest version, Junctions 10, was launched Wednesday 3 February 2021.
TRANSYT is traffic engineering software developed by the Transport Research Laboratory. It is used to model signalised highway networks and has the ability to model platooning.
