The initial costs for collision warning systems (CWS) can be high making it difficult for fleets that experience few crashes to deploy cost-effective solutions.

Nationwide,United States

Summary Information

The U.S. DOT sponsored an independent evaluation of a field operational test (FOT) of three advanced intelligent vehicle safety systems (IVSS): collision warning systems (CWS), adaptive cruise control (ACC), and advanced braking systems (AdvBS).
  • CWS installed on fleet vehicles (tractors) used in-cab visual displays and audible alarms to notify drivers to take corrective action if forward radar sensors detected a potential crash.
  • ACC maintained set headways between tractors and lead vehicles, and was designed to operate as a conventional cruise control system if no lead vehicle was present.
  • AdvBS installed on fleet vehicles used air disc brakes and an electronically controlled braking system to enhance braking performance and reduce stopping distances.
Data acquisition systems (DAS) were used to assess safety impacts "with" and "without" IVSS technologies installed on 100 trucks for 30 months starting in 2001. The following three combinations of IVSS technology were evaluated.
  • CWS
  • ACC + AdvBS
  • CWS + ACC + AdvBS (bundled system)
Impacts on crash rates were estimated based on an analysis of the frequency and severity of rear-end driving conflicts encountered. A driving conflict was defined as a safety-critical situation that had potential to result in a crash if the driver did not react quickly or sufficiently.


A high-level benefit-cost study was conducted to estimate the potential impacts of widespread deployment. The benefit-cost model evaluated four deployment scenarios:
  • CWS applied to a national fleet of 1.8 million tractor-trailer units.
  • CWS applied to 8 million commercial trucks over 10,000 pounds.
  • The bundled system (CWS + ACC + AdvBS) applied to a national fleet of 1.8 million tractor-trailer units.
  • The bundled systems applied to 8 million commercial trucks over 10,000 pounds.
Total societal benefits were derived from estimates of societal cost savings (i.e., property damage costs, bodily injury costs, fatality costs, medical and emergency response costs, lost productivity, lost quality of life, legal costs). System costs (recurring and non-recurring) were derived from manufacturers and component supplier contracts. A range of unit cost data (low versus high) was input into the model, and benefit impacts varied depending on the criteria selected to define conflicts.

The benefit-cost analysis assumed one-time start-up costs in the year 2005, recurring costs through 2024, and one replacement cycle (10 year lifetime). Benefit and cost values were discounted back to 2005 net present values using a four percent discount rate and a seven percent real discount rate to account for the time value of money.

Overall, the analysis indicated that the high initial costs for IVSS would make it difficult for fleets that experience few crashes to deploy cost-effective solutions. There was little or no economic justification for the widespread deployment on all large trucks. With respect to tractor trailers, however, future deployments of CWS were economically justified if relative deployment costs were lower.

See Also:

Evaluation of the Freightliner Intelligent Vehicle Initiative Field Operational Test Final Report, U.S. DOT, Report No. FHWA-OP-03-179, EDL No. 13871. September 2003.

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Evaluation of the Volvo Intelligent Vehicle Initiative Field Operational Test: Final Report - Version 1.3

Published By: U.S. DOT Federal Highway Administration

Source Date: 1/5/2007

EDL Number: 14352

Other Reference Number: FHWA-JPO-07-016



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Benefit ID: 2008-00581