Transportation Engineering School of Civil and Construction Engineering Karen Dixon Associate Professor, OSU Advisory Curve Speeds on Oregon Highways

Transportation Engineering School of Civil and Construction Engineering Research Objectives Identify the basis for the current and proposed advisory speed posting procedures for horizontal curves and passenger vehicles Identify current Oregon placement strategies at a variety of locations Identify potential future criteria for establishing advisory speeds and determine impact

Transportation Engineering School of Civil and Construction Engineering Presentation Overview Background Information on Advisory Speeds Advisory Speed Candidate Posting Thresholds State of Practice in Oregon Data Collection and Evaluation Findings Conclusions

Transportation Engineering School of Civil and Construction Engineering Why Do We Care? MUTCD recently changed recommendations National Committee on Uniform Traffic Control Devices has proposed additional changes for the next edition of the MUTCD Oregon currently has one of the most conservative policies in the U.S.

Transportation Engineering School of Civil and Construction Engineering Background Highlights Common Assessment Techniques include: Ball-bank indicator (Manual or Digital) Computational Approach Safe Speed Curves Other Cited Techniques (85 th -percentile, engineering judgment, engineering study, driver perception)

Transportation Engineering School of Civil and Construction Engineering MUTCD Advisory Speeds Current MUTCD – 16-degree for all speeds Past Procedures for ball-bank thresholds: 14-degrees (30 mph or less) 12-degrees (35 to 55 mph) 10-degrees (60 mph or more) Or: 10-degrees for all speeds

Transportation Engineering School of Civil and Construction Engineering Oregon Advisory Speed Policy 13-degrees (30 mph or less) 10-degrees (35 to 55 mph) 7-degrees (60 mph or more)

Transportation Engineering School of Civil and Construction Engineering Presentation Overview Background Information on Advisory Speeds Advisory Speed Candidate Posting Thresholds State of Practice in Oregon Data Collection and Evaluation Findings Conclusions

Transportation Engineering School of Civil and Construction Engineering MUTCD Advisory Speeds Future MUTCD Recommendation for passenger car -- ball-bank thresholds for: 16-degrees (30 mph or less) 14-degrees (35 to 55 mph) 12-degrees (60 mph or more) These values represent 8 to 10 mph the average driver presently exceeds current posted advisory speeds

Transportation Engineering School of Civil and Construction Engineering Additional Recommendations by the National Committee on Uniform Traffic Control Devices Engineering Study based on procedures including ball-bank criteria, accelerometer readings, or calculations using equivalent side friction values (to be modified slightly) Create truck advisory speed of 12- degrees Permit staged implementation over a period of 10 to 15 years

Transportation Engineering School of Civil and Construction Engineering Presentation Overview Background Information on Advisory Speeds Advisory Speed Candidate Posting Thresholds State of Practice in Oregon Data Collection and Evaluation Findings Conclusions

Transportation Engineering School of Civil and Construction Engineering Survey Results Oregon County Summary

Transportation Engineering School of Civil and Construction Engineering Survey Results Random Sample of Oregon Cities

Transportation Engineering School of Civil and Construction Engineering Presentation Overview Background Information on Advisory Speeds Advisory Speed Candidate Posting Thresholds State of Practice in Oregon Data Collection and Evaluation Findings Conclusions

Transportation Engineering School of Civil and Construction Engineering Oregon Data Collection Plan 160 Target Sites 32 Sites per each of 5 ODOT Regions 16 State Highways per Region 16 Local Highways per Region

Transportation Engineering School of Civil and Construction Engineering Summary of Sites ODOT Region State Site (curves) County Site (curves) 117 (19)16 (22) 215 (23)16 (30) 316 (23)16 (26) 416 (21)22 (30) 516 (18)16 (19)

Transportation Engineering School of Civil and Construction Engineering Summary of Study Locations Insert map graphic here

Transportation Engineering School of Civil and Construction Engineering Manual Ball-Bank Indicator

Transportation Engineering School of Civil and Construction Engineering Electronic Ball-Bank Indicator

Transportation Engineering School of Civil and Construction Engineering Ball-Bank Indicators Mounted in Vehicle

Transportation Engineering School of Civil and Construction Engineering Presentation Overview Background Information on Advisory Speeds Advisory Speed Candidate Posting Thresholds State of Practice in Oregon Data Collection and Evaluation Findings Conclusions

Transportation Engineering School of Civil and Construction Engineering How Well did the Observed Sites Comply with Current Oregon Advisory Speed Policy?

Transportation Engineering School of Civil and Construction Engineering Compliance Definitions Equal To – Posted Advisory Speeds were equal to recommended advisory speeds based on field ball-bank evaluations Less than or Equal To – Posted Advisory Speeds were equal to or less than recommended advisory speeds based on field ball-bank evaluations

Transportation Engineering School of Civil and Construction Engineering When is an Advisory Speed Plaque Needed? When the recommended advisory speed is more than 5 mph below the speed limit (in other words, 10 mph below the speed limit since we post in 5 mph intervals)

Transportation Engineering School of Civil and Construction Engineering Compliance for Speeds Equal to Recommended Advisory Speed (All Curves) -- Oregon Policy Based on Manual Ball- bank Readings State – Recommended Advisory Speed (mph) Total Compliance Sites Total Curve Directions % ComplianceNA % County – Recommended Advisory Speed (mph) Total Compliance Sites Total Curve Directions % Compliance % Numbers Rounded so Totals are Approximate

Transportation Engineering School of Civil and Construction Engineering Compliance for Speeds Equal to or Less Than Recommended Advisory Speed (All Curves) -- Oregon Policy State – Recommended Advisory Speed (mph) Total Compliance Sites Total Curve Directions % ComplianceNA County – Recommended Advisory Speed (mph) Total Compliance Sites Total Curve Directions % Compliance Numbers Rounded so Totals are Approximate

Transportation Engineering School of Civil and Construction Engineering Speed Plaque Locations Only State: 114 County: 142 Total: 256 Curve Directions Plaque Posting Equal to Recommended Advisory Speed Current Speed Plaques State Roads 54% County Roads 38% Speed Plaques Warranted State Roads 42% County Roads 32%

Transportation Engineering School of Civil and Construction Engineering How Well did the Observed Sites Comply with Current and Proposed MUTCD Advisory Speed Recommendations?

Transportation Engineering School of Civil and Construction Engineering All Study Locations (with or without Speed Plaques) State: 210 County: 246 Total: 456 Curve Directions Advisory Speed Indications Comply with (Equal To) Recommended Advisory Speeds State Roads Oregon % MUTCD 16- degree 53% Future % County Roads Oregon % MUTCD 16-degree 38% Future %

Transportation Engineering School of Civil and Construction Engineering Oregon Ball-bank Manual vs Digital Advisory Speeds

Transportation Engineering School of Civil and Construction Engineering Presentation Overview Background Information on Advisory Speeds Advisory Speed Candidate Posting Thresholds State of Practice in Oregon Data Collection and Evaluation Findings Conclusions

Transportation Engineering School of Civil and Construction Engineering Summary of Findings Current Oregon Policy compliance varies, but advisory speeds of 30 to 45 mph consistently have a lower compliance Compliance defined as Equal to Recommended Advisory Speed much more rigid than a definition of Equal to or Less than

Transportation Engineering School of Civil and Construction Engineering Summary of Findings Future threshold at Advisory Plaque Sites okay for 35% of the sites (with 80% equal to or less than this less conservative criteria) Future threshold at All Study Sites okay for 29% to 38% of the sites (using Equal To threshold)

Transportation Engineering School of Civil and Construction Engineering Questions?