Headway analysis at signalised intersections - with and without countdown timer

Discharge time headway, defined as time elapsed between constructive vehicles as they get discharged from a queue, is an important parameter in the analysis of signalized intersections. Reported studies in this area so far observed the discharge headway to be high at the start of green for the first few vehicles and stabilize to a minimum value by the 4th of 5th vehicle in the queue, which continues till the end of the queue. However, these studies were analyzing data from homogenous traffic conditions, which may not hold good for heterogeneous traffic conditions, such as the ones existing in India. Also, most of the intersections in India have signals facilitated with countdown timers, indicating the time remaining for change of signal phase, which is also expected to affect queue discharge characteristics. This paper quantitatively analyzes the changes in discharge headway characteristics in the presence and absence of countdown timers under heterogeneous traffic conditions and compares the results against the standard discharge headway distribution. The analysis was carried out using data collected from selected intersections in Chennai, India by videographic technique. The results indicate that the presence of timers considerably reduces the initial losses and delays, leading to a more efficient intersection. These observations will be useful for practicing engineers to design the signals and to decide on the requirement of countdown timers.

  • Supplemental Notes:
    • Abstract reprinted with permission from the publisher.
  • Authors:
    • Harshitha, M S
    • Agarwal, Sonu
    • Vanajakshi, Lelitha
  • Publication Date: 2012


  • English

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 33-40
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01444385
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 8 2012 10:03AM