Evaluation of The TAPCO Sequential Dynamic Curve Warning System

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PUBLICATION NO. FHWA-HIF-13-040
June 2013

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Technical Report Documentation Page
1. Report No. FHWA-HIF-13-040	2. Government Accession No. N/A			3. Recipient’s Catalog No. N/A
4. Title and Subtitle EVALUATION OF THE TAPCO SEQUENTIAL DYNAMIC CURVE WARNING SYSTEM				5. Report Date June 2013
				6. Performing Organization Code
7. Author(s) Omar Smadi, Neal Hawkins, Shauna Hallmark, Skylar Knickerbocker				8. Performing Organization Report No.
Center for Transportation Research and Education Iowa State University 2711 S. Loop Drive, Suite 4700 Ames, IA 50010				10. Work Unit No.
				11. Contract or Grant No. DTFH61-10-D-00025
12. Sponsoring Agency Name and Address Federal Highway Administration 1200 New Jersey Avenue, SE Washington, DC 20590				13. Type of Report and Period Covered Interim Report
				14. Sponsoring Agency Code
15. Supplementary Notes Work performed as a subcontractor to SAIC, under the direction of Julie Zirlin, FHWA Contracting Officer's Technical Manager.
16. Abstract Implementing safety countermeasures on rural horizontal curves to address speeding can improve the safety performance for those locations. State safety and traffic engineers are faced with making decisions on what type of technology to use and which sites to use the technology on in a fiscally constrained environment. The research conducted for this project will evaluate a Sequential Dynamic Curve Warning System (SDCWS) that could be an additional tool for these engineers to use either separately or in combination with other countermeasures to address horizontal curve locations with a history of safety concerns.
17. Key Words horizontal curves—dynamic signs—SDCWS			18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
9. Security Classif. (of this report) Unclassified		20. Security Classif. (of this page) Unclassified			21. No. of Pages 118	22. Price N/A

Form DOT F 1700.7 (8-72)

Reproduction of completed page authorized

SI* (Modern Metric) Conversion Factors
APPROXIMATE CONVERSIONS TO SI UNITS					APPROXIMATE CONVERSIONS FROM SI UNITS
Symbol	When You Know	Multiply By	To Find	Symbol	Symbol	When You Know	Multiply By	To Find	Symbol
LENGTH					LENGTH
in	inches	25.4	millimeters	mm	mm	millimeters	0.039	inches	in
ft	feet	0.305	meters	m	m	meters	3.28	feet	ft
yd	yards	0.914	meters	m	m	meters	1.09	yards	yd
mi	miles	1.61	kilometers	km	km	kilometers	0.621	miles	mi
AREA					AREA
in²	square inches	645.2	square millimeters	mm²	mm²	square millimeters	0.0016	square inches	in²
ft²	square feet	0.093	square meters	m²	m²	square meters	10.764	square feet	ft²
yd²	square yards	0.836	square meters	m²	m²	square meters	1.195	square yards	yd²
ac	acres	0.405	hectares	ha	ha	hectares	2.47	acres	ac²
mi²	square miles	2.59	square kilometers	km²	km²	square kilometers	0.386	square miles	mi²
VOLUME					VOLUME
fl oz	fluid ounces	29.57	milliliters	ml	mL	milliliters	0.034	fluid ounces	fl oz
gal	gallons	3.785	liters	L	L	liters	0.264	gallons	gal
ft³	cubic feet	0.028	cubic meters	m³	m³	cubic meters	35.314	cubic feet	ft³
yd³	cubic yards	0.765	cubic meters	m³	m³	cubic meters	1.307	cubic yard	yd³
NOTE: Volumes greater than 1000 l shall be shown in m³
MASS					MASS
oz	ounces	28.35	grams	g	g	grams	0.035	ounces	oz
lb	pounds	0.454	kilograms	kg	kg	kilograms	2.202	pounds	lb
T	short tons (2000 lb)	0.907	megagrams	Mg	Mg (or "t")	megagrams (or "metric ton")	1.103	short tons (2000 lb)	T
TEMPERATURE (exact degrees)					TEMPERATURE (exact degrees)
°F	Fahrenheit	5(F–32)/9 or (F–32)/1.8	Celcius	°C	°C	Celsius	1.8C +32	Fahrenheit	°F
ILLUMINATION					ILLUMINATION
fc	foot–candles	10.76	lux	lx	lx	lux	0.0929	foot–candles	fc
fl	foot–Lamberts	3.426	candela/m²	cd/m²	cd/m²	candela/m²	0.2919	foot–Lamberts	fl
FORCE and PRESSURE or STRESS					FORCE and PRESSURE or STRESS
lbf	pounds	4.45	newtons	N	N	newtons	0.225	poundforce	lbf
lbf/in²	pound per square inch	6.89	kilopascals	kPa	kPa	kilopascals	0.145	poundforce per square inch	lbf/in²

*SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003)

Introduction

Literature Review

Selection of Test Sites for SDCWS

Installation

Technology Description

Methodology for Speed Data Collection

Speed Analysis

Appendix B. Site Data Tables and Figures

Iowa Highway 144
Missouri Highway 221
Washington SR 7
Washington SR 9
Washington SR 203
Wisconsin Highway 20
Wisconsin Highway 67
Wisconsin Highway 213
Texas FM 109
Texas FM 407
Texas FM 530
Texas FM 1148

References

List of Figures

Figure 1	Photo: Northbound Interstate 5 DSFS systems in Oregon⁽²²⁾
Figure 2	Photo. Southbound Interstate 5 DSFS systems in Oregon⁽²²⁾
Figure 3	Photo. DSFS system in Norfolk. ⁽²³⁾
Figure 4	Photo. DSFS system in Bellevue, Washington ⁽²⁴⁾
Figure 5	Photo. Speed warning sign in the Sacramento River Canyon ⁽²⁶⁾
Figure 6	Photo. Comparison of curve warning sign (left) and speed feedback sign (right)⁽³⁰⁾
Figure 7	Equation. True effect
Figure 9	Photo. Southbound Interstate 5 DSFS systems in Oregon.
Figure 8.	Photo. Candidate curve site in Washington State
Figure 10.	Chart. Example site visit speed data collection form
Figure 11.	Photo. Example field report from initial visit
Figure 12	Map. Final test site locations
Figure 13	Photos. Installation of the SDCWS
Figure 14	Photo. SDCWS activation sequence
Figure 15	Diagram. Typical traffic counter placement
Figure 16	Photo. Iowa Highway 144 before data collection
Figure 17	Photo. Iowa Highway 144 1 month after data collection.
Figure 18	Photo. Iowa Highway 144 site layout
Figure 19	Chart. Iowa Highway 144 site information
Figure 20	Photo. Missouri Highway 221 before data collection
Figure 21	Photo. Missouri Highway 221 1 month after data collection
Figure 22	Photo. Missouri Highway 221 site layout
Figure 23	Chart. Missouri Highway 221 site information
Figure 24	Map. Washington State Route 9 before data collection
Figure 25	Map. Washington State Route 9 1 month after data collection.
Figure 26	Chart. Washington State Route 9 site information
Figure 27	Map. Washington State Route 203 before data collection
Figure 28	Map. Washington State Route 203 1 month after data collection
Figure 29	Chart. Washington State Route 203 site information.
Figure 30	Map. Washington State Route 7 before data collection.
Figure 31	Photo. Washington State Route 7 1 month after data collection
Figure 32	Chart. Washington State Route 7 site information.
Figure 33	Map. Wisconsin Highway 213 before data collection
Figure 34	Map. Wisconsin Highway 213 1 month after data collection.
Figure 35	Map. Wisconsin Highway 213 site layout.
Figure 36	Chart. Wisconsin Highway 213 site information.
Figure 37	Map. Wisconsin Highway 20 before data collection
Figure 38	Map. Wisconsin Highway 20 1 month after data collection.
Figure 39	Map. Wisconsin Highway 20 site layout
Figure 40	Chart. Wisconsin Highway 20 site information
Figure 41	Map. Wisconsin Highway 67 before data collection
Figure 42	Map. Wisconsin Highway 67 1 month after data collection
Figure 43	Map. Wisconsin Highway 67 site layout.
Figure 44	Chart. Wisconsin Highway 67 site information
Figure 45	Graph. Impact on vehicle speed - Iowa Hwy 144
Figure 46	Map and graphs. Location and change in percentile vehicle speed - Iowa Hwy 144
Figure 47	Graph. Impact on vehicle speed - Missouri Hwy 221
Figure 48	Map and graphs. Location and change in percentile vehicle speed - Missouri Hwy 221
Figure 49	Graph. Impact on vehicle speed - Washington SR 7
Figure 50	Map and graphs. Location and change in percentile vehicle speed - Washington SR
Figure 51	Graph. Impact on vehicle speed - Washington SR 9
Figure 52	Map and graphs. Location and change in percentile vehicle speed - Washington SR
Figure 53	Graph. Impact on vehicle speed - Washington SR 203
Figure 54	Map and graphs. Location and change in percentile vehicle speed - Washington SR 203
Figure 55	Graph. Impact on vehicle speed - Wisconsin Hwy 20
Figure 56	Map and graphs. Location and change in percentile vehicle speed - Wisconsin Hwy 20
Figure 57	Graph. Impact on vehicle speed - Wisconsin Hwy 67
Figure 58	Map and graphs. Location and change in percentile vehicle speed - Wisconsin Hwy 67
Figure 59	Graph. Impact on vehicle speed - Wisconsin Hwy 213
Figure 60	Map and graphs. Location and change in percentile vehicle speed - Wisconsin Hwy 213.
Figure 61	Graph. Impact on vehicle speed - Texas FM 109
Figure 62	Map and graphs. Location and change in percentile vehicle speed - Texas FM 109.
Figure 63	Graph. Impact on vehicle speed - Texas FM 407
Figure 64	Map and graphs. Location and change in percentile vehicle speed - Texas FM 407.
Figure 65	Graph. Impact on vehicle speed - Texas FM 530
Figure 66	Map and graphs. Location and change in percentile vehicle speed - Texas FM 530
Figure 67	Graph. Impact on vehicle speed - Texas FM 1148.
Figure 68	Map and graphs. Location and change in percentile vehicle speed - Texas FM 1148

List of Tables

Table 1	Advisory message for Interstate 5 dynamic speed-activated feedback sign system
Table 2	Final test sites by State
Table 3	Curve characteristics
Table 4	Installation dates.
Table 5	Summary of results at point of curvature after 1 month.
Table 6	Summary of results at center of curve after 1 month
Table 7	Schedule of activities, all sites
Table 8	Results for Iowa - Hwy 144 at PC
Table 9	Results for Iowa - Hwy 144 at CC.
Table 10	Speed Reduction for Iowa - Hwy 144
Table 11	Results for Missouri - Hwy 221 at PC
Table 12	Results for Missouri - Hwy 221 at CC.
Table 13	Speed reduction for Missouri - Hwy 221
Table 14	Results for Washington - SR 7 at PC
Table 15	Results for Washington - SR 7 at CC
Table 16	Speed reduction for Washington - SR 7
Table 17	Results for Washington - SR 9 at PC
Table 18	Results for Washington - SR 9 at CC.
Table 19	Speed reduction for Washington - SR 9
Table 20	Results for Washington - SR 203 at PC
Table 21	Results for Washington - SR 203 at CC
Table 22	Speed reduction for Washington - SR 203
Table 23	Results for Wisconsin - Hwy 20 at PC
Table 24	Results for Wisconsin - Hwy 20 at CC
Table 25	Speed reduction for Wisconsin - Hwy 20
Table 26	Results for Wisconsin - Hwy 67 at PC
Table 27	Results for Wisconsin - Hwy 67 at CC
Table 28	Speed Reduction for Wisconsin - Hwy 67
Table 29	Results for Wisconsin - Hwy 213 at PC
Table 30	Results for Wisconsin - Hwy 213 at CC.
Table 31	Speed reduction for Wisconsin - Hwy 213
Table 32	Results for Texas - FM 109 at PC
Table 33	Results for Texas - FM 109 at CC
Table 34	Results for Texas - FM 407 at PC
Table 35	Results for Texas - FM 407 at CC.
Table 36	Results for Texas - FM 530 at PC
Table 37	Results for Texas - FM 530 at CC
Table 38	Results for Texas - FM 1148 at PC
Table 39	Results for Texas - FM 1148 at CC

List of Abbreviations and Acronyms

AADT	Annual average daily traffic
Caltrans	California Department of Transportation
CC	Center of curve
DOT	Department of Transportation
DSFS	Dynamic speed feedback sign
FARS	Fatality Analysis Reporting System
GES	General Estimates System
HSIS	Highway Safety Information System
LIDAR	Light detection and ranging
MUTCD	Manual on Uniform Traffic Control Devices
PC	Point of curvature
SD	Standard deviation
SDCWS	Sequential Dynamic Curve Warning System
TE	True effect
VPD	Vehicles per day