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ACS Lite

Development, Testing & Results

ACS Lite is a scaled down version of the Federal Highway Administration's (FHWA) Adaptive Control Software (ACS); developed by FHWA in partnership with Siemens, University of Arizona and Purdue University. The software is licensed by Siemens and is currently licensed for integration by four traffic signal controller manufactures: Eagle, Econolite, McCain and Peek. Four field test sites were built to validate the operability of ACS Lite with each of the manufactures control systems. The results of the field test appear below; the benefits of the system are relative to how recently the signal timing was last updated prior to the test.

The Econolite ACS Lite test site was located on Hamilton Road in Gahanna, Ohio. The Hamilton Road test site incorporated ACS Lite at nine intersections which included a freeway interchange. Signal timing along the test route was updated just prior to the test resulting in minimal delay savings; however, no degradation of the signal timing is expected to occur as traffic demand trends change over time.

Benefits Analysis

Hamilton Road

Unit Costs:

• Total Delay - $12.10 per hour
• Stops - $0.014 per stop
• Fuel Consumed - $0.59 per liter ($2.25 per gallon)

	Before (per veh)	After (per veh)	Savings (per veh)	Peak Hours (all vehs)	Peak Hours Savings
Total Delay (hour)	0.03761	0.03758	0.00003	0.15588	$1.89
Total Stops	3.5	2.9	0.6	3117.6	$43.65
Fuel (Liters)	0.390	0.373	0.017	89.287	$53.08
Peak Hours Benefit	$98.61
Daily Benefit	$340.03
Annual Benefit	$88,500.00

The Eagle ACS Lite test site was located on State Route 6 in western Houston, Texas. State Route 6 connects to I-10 on the south and extends beyond George Bush International Airport to the north. The route incorporated 8 intersections and was last retimed in the fall of 2004. The benefits included a reduction in delay of over 23 seconds per vehicle.

Benefits Analysis

State Route 6

Unit Costs:

• Total Delay - $12.10 per hour
• Stops - $0.014 per stop
• Fuel Consumed - $0.59 per liter ($2.25 per gallon)

	Before (per veh)	After (per veh)	Savings (per veh)	Peak Hours (all vehs)	Peak Hours Savings
Total Delay (hour)	0.01856	0.01214	0.00642	39.16252	$473.87
Total Stops	1.7	1.2	0.5	3051.6	$42.72
Fuel (Liters)	0.490	0.455	0.035	214.837	$127.71
Peak Hours Benefit	$644.30
Daily Benefit	$2,221.72
Annual Benefit	$577,648.12

The Peek and McCain manufacturer test sites are located in Bradenton, FL and El Cajon, CA. The Bradenton test site has been fully integrated with ACS Lite and is currently undergoing data collection. The El Cajon, McCain test site is still under development. Upon completion of the last two field test all four manufacturers will begin offering ACS Lite for new systems and as an upgrade to existing systems.