Environmental Assessments

Traffic Emissions

SIDRA INTERSECTION and SIDRA TRIP for Environmental Assessments

Environmental assessment in traffic management, design, operations and planning can be conducted using models to estimate fuel consumption and pollutant emissions as a function of traffic conditions. For this purpose, the SIDRA INTERSECTION and SIDRA TRIP software packages use unique models based on work that won the Institute of Transportation Engineers 1986 Transportation Energy Conservation Award for research into energy savings from urban traffic management.

These power-based vehicle energy and emission models combined with a powerful lane-based traffic model enable transportation planners and engineers to carry out environmental analysis for assessing intersection and network traffic solutions. These detailed models incorporated in easy-to-use software packages can be valuable for professionals interested in realistic assessment of the effects of transport on the environment.

These models are documented extensively. This includes more recent research to calibrate the light and heavy vehicle parameters used in the models based on a large empirical database for a modern vehicle fleet.

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About the Models

Two essential elements of effective fuel consumption and emission modelling in relation to traffic management, design, operations and planning are:

  • A detailed traffic model that has sensitivity to traffic characteristics (road geometry, road grade, traffic control type, demand volumes, driver behaviour, acceleration - deceleration and other vehicle characteristics), and
  • fuel consumption and emission models that have the right sensitivities to vehicle parameters (fuel consumption and emission parameters sensitive to variations in traffic condition, mass, power, acceleration - deceleration characteristics, and so on) and at the same time are well integrated with the traffic model.

SIDRA INTERSECTION and SIDRA TRIP use different levels of model detail but both models are based on the same power-based model of vehicle fuel consumption and emissions.

SIDRA INTERSECTION is a micro-analytical software that uses a four-mode elemental (modal) model of fuel consumption and emissions. For each lane of traffic, it models vehicle paths (drive cycles) consisting of a series of cruise, acceleration, deceleration and idling (stopped) time elements determined for specific traffic conditions represented by intersection geometry, traffic control and demand volumes.

SIDRA TRIP is a single-trip microsimulation model for assessment of road traffic conditions using real-life traffic vehicle travel data (e.g. from GPS data) or user-defined drive cycles. It employs an instantaneous model to determine various trip characteristics for assessing traffic and travel level of service, performance (delay, speed, travel time), and provide estimates of fuel consumption, emissions, noise, operating cost and user cost.

Accuracy of the SIDRA instantaneous CO2 Emission model for a test car

CUEDC-P drive cycle used in SIDRA fuel consumption and emission tests

Graph of SIDRA instantaneous CO2 emission model estimates vs measured CO2 emissions
shows very high correlation

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