Benefit

A modeling study found that alerting drivers to the status of upcoming traffic signals led to smoother decelerations to the intersection, and thereby reduced fuel consumption and lowered emissions by up to 40 percent for passenger vehicles.

Evaluating advanced driving alert systems in which traffic signal status information is employed specifically for energy and emissions reductions.


10-14 January 2010
Nationwide; United States


Summary Information

Autos are a major contributor to Greenhouse Gas (GHG) emissions, particularly carbon dioxide (CO2) emissions, and unnecessary acceleration and hard braking in response to changing traffic signals, while not a major source of emissions, adds to wasted fuel and increased emissions. Alerting drivers to traffic signal status may help drivers avoid hard braking at intersections, resulting in lower fuel consumption and reduced emissions. A study modeled the effects of advanced driving alert systems (ADAS) for alerting drivers in advance of a traffic signal change, thus encouraging drivers to release the throttle and allow the vehicle to slowly cruise to a stop.

METHODOLOGY

The study modeled the impact of a roadside changeable message sign (CMS) and an in-vehicle driver alert system on fuel consumption and CO2 emissions. Although the savings for one vehicle at one intersection will be insignificant, the cumulative savings from a large number of vehicles over many occurrences and signal cycles could be substantial. Researchers used the Comprehensive Modal Emission Model (CMEM), which is a microscopic emissions simulation tool, to estimate the fuel consumption and emissions benefits. CMEM produces second-by-second vehicle trajectories (location, velocity, and acceleration) to estimate individual and aggregate fuel consumption and tailpipe emissions.

The drivers in the non-alert condition became aware of the red signal later than the drivers who received the alert, and used the maximum deceleration rate of 4.5 m/s2. Drivers in the alert condition received the alert 360 m ahead of the intersection, and released the accelerator so the vehicle slowed at the rate of 0.224 m/s2 until they applied the brake at the intersection. The estimates were made for three posted speed limits (55, 60, and 65 km/h) and included conditions for LDV24 (e.g., passenger vehicles) and LDV17 (a tier 1 light-duty truck such as a pick-up or a sport utility vehicle (SUV)).

FINDINGS

Results showed that the drivers alerted to the red signal 360 m ahead of the intersection reduced fuel consumption and CO2 emissions by up to 40 percent for passenger vehicles and 38 percent for pick-ups and SUVs at the posted speed limit of 65 km/h.


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Source

Energy and Emission Benefit Comparison between Stationary and In-Vehicle Advanced Driving Alert Systems

Author: Wu, Guoyuan; Kanok Boriboonsomsin; Wei-Bin Zhang; Meng Li; and Matthew Barth

Published By: Paper presented at the 89th Annual Transportation Research Board Meeting

Source Date: 10-14 January 2010

URL: http://trb.metapress.com/content/4665h831186q753u/

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Typical Deployment Locations

Statewide

Keywords

None defined

Benefit ID: 2011-00751