Bicycle Detection Using Caltrans Type D Loops: More Options for Practitioners

1. Bicycle Detection Using Caltrans Type D Loops:More Options for Practitioners Presented toITE District 6 Annual Meeting June 24-27, 2012 by John Kerenyi, P.E., Senior Engineer, City of Moreno Valley

2. Summary of Presentation California AB1581 Caltrans recommendations Desired configurations/deviation from Caltrans recommendations ILD theory of operation Type D loop field measurements Calculations/recommendations

3. California AB1581 At new or substantially modified intersections (>50% of detection replaced), re: detection: “To the extent feasible and in conformance with professional traffic engineering practice, to be installed and maintained so as to detect lawful bicycle or motorcycle traffic on the roadway.” AB1581 became effective in 2010

4. Caltrans Guidance—Requirements • Reference rider described • 4 ft tall • 90 lbs min • 16” aluminum wheels, non-ferromagnetic frame • Reference rider described in a manner suitable for testing detection by many means e.g. ILD, video, microwave • Either detect reference rider, or place approach on recall (semiactuated/pretimed operation allowed) • Bike pushbuttons not enough anymore • Bike min green timing recommended

5. Caltrans Type D Loop

6. Type D Loop Variations City of Los Angeles City of Moreno Valley

7. Caltrans’ Type D Loop Recommendations Wire in series with three other standard (e.g. round or octagonal) loops which are connected in parallel to each other Wire in series with two other standard loops Wire to own detector card channel D D D E E E E E Detector Card Detector Card Detector Card

8. D D D D E E E E E E Desired Configurations Case 1: Two loops in one lane Case 3: Four loops in two lanes Case 2: Four loops in one lane

9. ILD Theory of Operation

10. Sensitivity

11. Series or parallel? Detector Card Detector Card D D E E E Case 1 D Parallel wiring Series wiring LD = 190 μH (Five Turns) LE = 60 μH (Three Turns) Sensitivity factor Seek to minimize Scircuit = 0.76 SD Scircuit = 0.24 SD

12. SD minimized by placing the Type E loops in series D D D E E E E E E E E E Case 2 Parallel wiring Series wiring Minimize Maximize SD minimized by placing the Type E loops in parallel SF: 0.61 (4 turns) SF: 0.51 (3 turns) Detector Card Detector Card

13. Case 3 D D D D D D D D D D E E E E E E E E E E Detector Card Detector Card Configuration 1 Configuration 2 SF: 0.33 SF: 0.17 Detector Card Detector Card Configuration 3 Configuration 4 SF: 0.26 SF: 0.17

14. Discrimination ofBicycles and Vehicles • Desirable to avoid timing long minimum greens every cycle for occasional bicycles • Known efforts • OCTEC ILD method • Microwave: Intersector, others • Video detection manufacturers

15. Detector Card D D D D E E E E E E Recommendations • Case 1 (two loops): Parallel • Case 2 (one D and three E): Parallel/series (opposite ofCaltrans recommendation) • Case 3 • Further research is necessary esp. for splashover Detector Card Detector Card