Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Appendices
the ramp metering system. It is assumed that the lifetime of the ramp metering system is 5
years.
From the literature (1, 2, 3 and 4), it is estimated that the average unit capital cost for the
installation of a ramp meter is approximately $30,000 and that the maintenance and operating
cost per year is $2,200. Assuming an annual interest rate of 3%, the total cost of installing and
maintaining the two ramp meters over a five-year period is estimated to be $78,403. The net
present value of the reliability improvement over five yields $520,264 in savings.
Thus, the Benefit-Cost ratio is estimated to be 6.6:1. These calculations are summarized in
Table D.4. It should be noted that this is a rough estimate that only considers the benefits of the
morning peak period and is provided for illustrative purposes. If the safety benefits and the
reduction in fuel emissions were considered, a higher benefit-cost ratio could be calculated. In
addition, the ramp delay experienced by some users is a disbenefit. A simple benefit-cost
calculation does not reflect changes in volume or travel time variability in future years.
Table D.4 - Summary of Benefit-Cost Ratio Calculations
Step 6 – Compare the Results with other Similar Treatments
As a final step in this analysis, a literature review was conducted to estimate the benefit of other
ramp metering projects toward improving travel time reliability. Direct assessments of reliability
improvements were not found. (Hence, the importance of the methodology in this document is
SAMPLE PROBLEM-QUANTIFYING THE ECONOMIC BENEFIT OF IMPROVING TRAVEL-TIME RELIABILITY Page D-12