Benefit

Adaptive signal control systems installed on two corridors in Colorado have benefit-to-cost ratios ranging from 1.6:1 to 6.1:1.

Experience implementing adaptive signal control systems in Colorado.


07/01/2012
10th Street Corridor,Greely,Colorado,United States; Woodland Park Corridor,Colorado,United States


Summary Information

This project evaluated the benefits of installing InSync and QuicTrack real-time adaptive signal control systems installed on two corridors in Colorado. The InSync system was installed on 10th Street (US 34 Business) in Greeley, and the QuicTrac system was installed on US-24 in Woodland Park. The Colorado DOT collected traffic data before and after each system was activated in early 2012.

The InSync system was adapted to existing signal controller hardware at 11 intersections on a four mile section of the 10th Street corridor. The QuicTrac system was adapted to existing signal controller hardware at eight intersections on a 3.65 mile section of US-24. A high-speed communications network connected all intersections to a central system that enabled operators to control the systems and view performance data and camera images remotely.

METHODOLOGY

A benefit cost analysis was completed to determine how long each system would take to pay for itself. Before and after data were collected to evaluate performance and the following factors were used to calculate benefit-to-cost estimates:
  • Travel time
  • Fuel consumption
  • Side-street delay
  • Design and engineering cost
  • Adaptive system cost
  • Detection/communication upgrade cost
  • Construction/installation cost
  • Staff time spent for design, installation, and training
  • Expected annual maintenance
Data collected prior to installation represented corridor performance using coordinated signal control operations with timing schemes updated every few years. After adaptive signal control systems were installed, traffic sensors enabled signal timing to be changed as needed to accommodate prevailing traffic conditions. Before and after travel time runs were conducted on each corridor to evaluate travel times in each direction of travel during six different time periods for weekdays and one time period for weekends. Simulation software was used to estimate delay and changes to level of service.

To calculate the cost savings in terms of reduced travel time and fuel consumption, the total travel time (vehicle-hours) was multiplied by the value of time and vehicle occupancy values for the area and the fuel consumption savings were multiplied by the average per gallon fuel cost for the area. The value of time for both corridors was estimated at $15.00 per person per hour, average vehicle occupancy for both highways was estimated at 1.3 people per vehicle, and the average fuel costs were estimated at $3.65 per gallon in Greeley and $3.50 in Woodland Park. Annual benefit-to-cost ratios were computed based upon a 350 day year (250 weekdays and 100 weekend days). Days with non-typical travel volumes (holidays, events, weather, etc.) were omitted from the analysis.

FINDINGS

The tables below excerpted from the source report show significant annual savings to both corridors. The 10th Street analysis predicted a user savings of more than $1.326 million dollars, and the US-24 analysis predicted a user savings of almost $900,000 per year.

10th Street Annual Benefit (combined weekday and weekend)

Measure of Effectiveness
Daily Benefit
Daily CostAnnual Cost
Travel Time (vehicle hours)
207
$4,034
$1.412 million
Fuel Consumption (gallons)
122
$445
$156,000
Side-street delay (vehicle hours)
-41
-$805
-$282,000
Annual Maintenance (estimates indicated 1163 hours saved per year at $35 per hour)
$115
$40,700
TOTAL
$3,789
$1.326 million

US-24 Annual Benefit (combined weekday and weekend)

Measure of Effectiveness
Daily Benefit
Daily CostAnnual Cost
Travel Time (vehicle hours)
191
$3,730
$1.305 million
Fuel Consumption (gallons)
149
$522
$183,000
Side-street delay (vehicle hours)
-87
-$1,698
-$594,000
Annual Maintenance (estimates indicated 130 hours saved per year at $35 per hour)
$12.86
$4,500
TOTAL
$2,567
$898,000

The table below excerpted from the source report provides an overall summary of benefits and costs.

InSync System
QuicTrac System
Category
Actual Project
Minimal Project*
Actual Project
Minimal Project*
Number of Intersections
11
8
Daily cost saving (corridor)
$3,789
$2,567
Annual cost saving (corridor)
$1.326 million
$898,500
Install costs (corridor)
$905,500
$375,000
$176,300
$162,400
Daily cost saving (per intersection)
$344
$321
Annual cost saving (per intersection)
$120,500
$112,300
Install costs (per intersection)
$82,300
$34,000
$22,000
$20,300
Benefit-to-cost ratio
1.58
3.79
5.64
6.10
10-year projected savings
$4.2 million
$4.7 million
$2.8 million
$2.8 million
20-year projected savings
$9.2 million
$9.7 million
$5.7 million
$5.7 million
AADT (Colorado DOT data near middle of corridor)
26,500 vehicles
22,500 vehicles
Daily cost saving per user
$0.14
$0.11
Annual cost saving per user (assume 350 day use of road)
$49.00
$38.50
*Minimal project assumes the corridor has the necessary equipment to implement the system as a "plug and play" solution.

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Source

Adaptive Signal Timing Comparison Between the InSync and Quictrac Adaptive Signal Systems Installed in Colorado

Author: Sprague, David

Published By: Colorado DOT

Source Date: 07/01/2012

Other Reference Number: Report No. CDOT-2012-6

URL: http://www.coloradodot.info/programs/research/pdfs/2012/adaptivesignaltiming.pdf

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Goal Areas

Productivity

Typical Deployment Locations

Metropolitan Areas

Keywords

traffic signals, adaptive signals

Benefit ID: 2014-00925