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ACS-Lite Split Tuning Algorithm

ACS-Lite Split Tuning Algorithm. Split Tuning Process. STEP 1. Collect data Correlate data to signal phasing Perform analysis Implement phase split adjustments. STEP 2. STEP 3. STEP 4. STEP 1.

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ACS-Lite Split Tuning Algorithm

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  1. ACS-Lite Split Tuning Algorithm

  2. Split Tuning Process STEP 1 Collect data Correlate data to signal phasing Perform analysis Implement phase split adjustments STEP 2 STEP 3 STEP 4

  3. STEP 1 Occupancy Data is collected from stop bar detectors. Inductive Loops, Video and Radar detectors have worked effectively with ACS-Lite.

  4. Ø7 Ø4 Ø8 Ø3 Occupancy data is correlated to phase intervals by the intersection controller. This data is sent to ACS-Lite allowing phase utilization information to be developed for each cycle. STEP 2 Ø4 Ø7 Ø2 Ø2 Ø2 Ø1 Ø7 Ø5 Ø5 Ø5 Ø6 Ø4 Ø3 Ø8 Ø8 Ø3

  5. ACS-Lite averages the phase utilization data for several cycles to determine the degree of saturation for each phase. STEP 3 Ø3 Cycle 1 Ø3 Cycle 2 Averaging Ø3 Cycle 3 Ø3 Cycle 4 Ø3 Phase Utilization

  6. ACS-Lite balances the degree of saturation for all phases by adjusting splits. The result is more efficient use of available green time across all phases. STEP 4 Ø4 Ø7 Ø2 Ø5 Ø1 Ø6 Ø3 Ø8

  7. Split Adjustment Example • The following slides present an example of the ACS-Lite split adjustment algorithm. • A software in the loop simulation was developed using CORSIM with an NTCIP runtime extension to interface with the ACS-Lite software. • The simulation was conducted on SR-26 in Lafayette, IN. • The simulation runs for one hour beginning at 7:00am, snapshots are provided at key times throughout the hour to demonstrate the outcome of split tuning.

  8. 7:06 AM ACS-Lite has collected data for 5 cycles. The N/B Left Turn (Phase 3) is reporting a 100% degree of saturation. The intersection is running a 70sec cycle with a 10 second split for Phase 3. ACS-Lite is ready to implement a split adjustment. Ø4 Ø7 Ø2 Ø5 Ø1 Ø6 Ø3 Ø8

  9. The first split adjustment was implemented just after 7:06am increasing the phase 3 split from 10 to 13 seconds. After the adjustment data is collected for 5 cycles. The N/B Left Turn (Phase 3) continues to report a 100% degree of saturation. ACS-Lite is ready to implement a second split adjustment. 7:14 AM Ø4 Ø7 Ø2 Ø5 Ø1 Ø6 Ø3 Ø8

  10. The second split adjustment was implemented just after 7:14am increasing the phase 3 split from 13 to 15 seconds. Phase utilization data is collected for 5 cycles. The N/B Left Turn (Phase 3) continues to report a 100% degree of saturation; notice the queue has been reduced. ACS-Lite is ready to implement a third split adjustment. 7:24 AM Ø4 Ø7 Ø2 Ø5 Ø1 Ø6 Ø3 Ø8

  11. The third split adjustment was implemented just after 7:24am increasing the phase 3 split from 15 to 17 seconds. After the adjustment data is collected for 5 cycles. The N/B Left Turn (Phase 3) continues to report a 100% degree of saturation; notice the queue has been eliminated. ACS-Lite recognizes that this is the optimal split for the current phase 3 demand. 7:34 AM Ø4 Ø7 Ø2 Ø5 Ø1 Ø6 Ø3 Ø8

  12. After collecting data for 5 additional cycles ACS-Lite retains the N/B Left Turn (Phase 3) split at 17 seconds. The degree of saturation has been balanced across all the phases. As conditions change ACS-Lite will make the appropriate split adjustments. 7:46 AM Ø4 Ø7 Ø6 Ø1 Ø5 Ø2 Ø3 Ø8

  13. After collecting additional data, ACS-Lite retains the N/B Left Turn (Phase 3) split at 17 seconds. The intersection is operating optimally. Additional split changes will be made as necessary to meet the demand needs of the intersection. 7:56 AM Ø4 Ø7 Ø6 Ø1 Ø5 Ø2 Ø3 Ø8

  14. Questions? If you would like additional information about ACSLite or have questions please email acslite@dot.gov

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