bicycle detection using caltrans type d loops: more options for practitioners
DESCRIPTION
Bicycle Detection Using Caltrans Type D Loops: More Options for Practitioners. Presented to ITE District 6 Annual Meeting June 24-27, 2012 by John Kerenyi, P.E., Senior Engineer, City of Moreno Valley. Summary of Presentation. California AB1581 Caltrans recommendations - PowerPoint PPT PresentationTRANSCRIPT
Bicycle Detection Using Caltrans Type D Loops:More Options for Practitioners
Presented toITE District 6 Annual Meeting
June 24-27, 2012by John Kerenyi, P.E., Senior Engineer,
City of Moreno Valley
Summary of Presentation
• California AB1581• Caltrans recommendations• Desired configurations/deviation from
Caltrans recommendations• ILD theory of operation• Type D loop field measurements• Calculations/recommendations
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
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
Caltrans Type D Loop
Type D Loop Variations
City of Moreno Valley
City of Los Angeles
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
Detector Card
D
E E
Detector Card
D
E EEDetector
CardD
Desired Configurations
E D
E D
E D
E DE E
Case 1:Two loops in one lane
Case 3:Four loops in two lanes
Case 2:Four loops in one lane
ILD Theory of Operation
Sensitivity
Series or parallel?E D
E
DDcircuit
L
LSS
1
1
Parallel wiring
D
EDcircuit
LL
SS
1
1
Series wiring
DDetector
Card E
DDetector
Card
E
Seek to minimize
LD = 190 μH
LE = 60 μH(Three Turns)
(Five Turns)
Scircuit = 0.76 SD Scircuit = 0.24 SD
Sensitivityfactor
Case 1
L
LS
Case 2E DE E
E
DDcircuit
L
LSS
1
1
D
EDcircuit
LL
SS
1
1
Parallel wiring Series wiring
Maximize
Minimize
SD minimized by placing the Type E loops in series
SD minimized by placing the Type E loops in parallel
E
E
E
DDetector
Card
D
Detector Card
E E E
SF: 0.61(4 turns)
SF: 0.51(3 turns)
Case 3E D
E D
E
DD
Detector Card
EE
DDetector
Card
E
E
D
D
Detector Card
E
D
E
DDetector
CardE
D
Configuration 1 Configuration 2
Configuration 3 Configuration 4
SF: 0.33 SF: 0.17
SF: 0.26 SF: 0.17
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
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
DDetector
Card E
E
E
E
DDetector
Card
E
DD
Detector Card
E