IDEAS home Printed from
   My bibliography  Save this paper

Assessing URET Benefits for Airspace Users: A Quasi-Experimental Approach


  • Bolic, Tatjana
  • Hansen, Mark


Air traffic control organizations around the world are trying to develop automation tools to help controllers manage increasing workload and to enable user preferred routes. This paper focuses on such a tool: User Request Evaluation Tool (URET), which is a decision-support tool for en-route controllers. URET is a prototype of an automated conflict probe. Based on flight plans and actual radar tracks, the URET system models aircraft trajectories and predicts possible conflicts. It also enables controllers to check clearances for conflicts prior to their issuance. This tool is intended as a strategic decision-support tool for the D-side controller. When implemented in the Air traffic control system, tools like URET can affect many aspects of system performance, from controller workload, to safety, to the quality of service provided to users. The purpose of this paper is to determine the impact of URET on users--more specifically on flight times experienced by users. To do so, we employ statistical methods that compare changes in flight times before and after URET implementation for two sets of flights. One set includes flights that traverse the airspace where URET is implemented; the other includes flights that do not use that airspace. Results suggest that URET reduces flight times for flights using the URET airspace. Departure delay, rather than airborne time, is the flight time component that is most strongly affected, with a decrease of 0.5-3 minutes per flight depending on the analysis approach and time period analyzed. Airborne time reductions are in the range of 0.2-0.5 minutes per flight under one analysis approach, and statistically insignificant under the other approach. These results imply that much of the benefit from URET is non-local and derives from mechanisms other than more direct routing through URET airspace, which has been the focus of most earlier benefits studies.

Suggested Citation

  • Bolic, Tatjana & Hansen, Mark, 2002. "Assessing URET Benefits for Airspace Users: A Quasi-Experimental Approach," Institute of Transportation Studies, Research Reports, Working Papers, Proceedings qt99h0s0rt, Institute of Transportation Studies, UC Berkeley.
  • Handle: RePEc:cdl:itsrrp:qt99h0s0rt

    Download full text from publisher

    File URL:;origin=repeccitec
    Download Restriction: no

    References listed on IDEAS

    1. Gaudry, Marc J. I. & Jara-Diaz, Sergio R. & Ortuzar, Juan de Dios, 1989. "Value of time sensitivity to model specification," Transportation Research Part B: Methodological, Elsevier, vol. 23(2), pages 151-158, April.
    2. Small, Kenneth A., 1983. "The incidence of congestion tolls on urban highways," Journal of Urban Economics, Elsevier, vol. 13(1), pages 90-111, January.
    3. Small, Kenneth A & Rosen, Harvey S, 1981. "Applied Welfare Economics with Discrete Choice Models," Econometrica, Econometric Society, vol. 49(1), pages 105-130, January.
    4. Londero, Elio, 1987. "Benefits and Beneficiaries: An Introduction to Estimating Distributional Effects in Cost-Benefit Analysis (Second Edition)," MPRA Paper 60345, University Library of Munich, Germany, revised 1996.
    5. K. M. Gwilliam, 2001. "Competition in Urban Passenger Transport in the Developing World," Journal of Transport Economics and Policy, University of Bath, vol. 35(1), pages 99-118, January.
    6. Jara-Díaz, Sergio R. & Videla, Jorge, 1989. "Detection of income effect in mode choice: Theory and application," Transportation Research Part B: Methodological, Elsevier, vol. 23(6), pages 393-400, December.
    7. Anders Karlstrom, 2003. "A Simple Method of Incorporating Income Effects into Logit and Nested-Logit Models: Theory and Application," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 85(1), pages 248-253.
    8. Niskanen, Esko, 1987. "Congestion tolls and consumer welfare," Transportation Research Part B: Methodological, Elsevier, vol. 21(2), pages 171-174, April.
    9. E A Vasconcellos, 1997. "The making of the middle-class city: transportation policy in Sao Paulo," Environment and Planning A, Pion Ltd, London, vol. 29(2), pages 293-310, February.
    10. H C W L Williams, 1977. "On the Formation of Travel Demand Models and Economic Evaluation Measures of User Benefit," Environment and Planning A, , vol. 9(3), pages 285-344, March.
    Full references (including those not matched with items on IDEAS)

    More about this item


    Access and download statistics


    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:cdl:itsrrp:qt99h0s0rt. See general information about how to correct material in RePEc.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Lisa Schiff). General contact details of provider: .

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    We have no references for this item. You can help adding them by using this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service hosted by the Research Division of the Federal Reserve Bank of St. Louis . RePEc uses bibliographic data supplied by the respective publishers.