Sunday, January 7, 2001 Neil R. Gross

Transcription

1 Workshop on Adaptive Traffic Signal Control Equipment Requirements for Adaptive Control -SCATS Sunday, January 7, 2001 Neil R. Gross Jan 7, 2001 TRB Adaptive Control Workshop 1

2 Sample System North/South Arterials Average Spacing 1112 feet 4 miles, 20 intersections Twenty Intersections in 4 miles, a busy stretch! Average Spacing, approx. fifth of a mile, Assumption - not all cross streets are significant, Busy Nth/Sth intersections shown, others minor Jan 7, 2001 TRB Adaptive Control Workshop 2

3 Sample System Subsystem structure shown below, Saves detectors at minor intersections, If minor intersection has variable splits then add detectors and make it a major intersection. Subsystem 1 Subsystem 2 Subsystem 3 Subsystem 4 4 miles, 20 intersections Jan 7, 2001 TRB Adaptive Control Workshop 3

4 Data Requirements SCATS detectors (16 x 6 ft at stop line) in each lane at the major intersections, Detectors, preferably SCATS detectors, in each side street lane and in main street left turn lanes, at the minor intersections, If detectors are 6ft x 6ft at minor intersections they will work OK for tactical use. If longer they will not be as effective. Jan 7, 2001 TRB Adaptive Control Workshop 4

5 Major Intersection Jan 7, 2001 TRB Adaptive Control Workshop 5

6 Minor Intersection Jan 7, 2001 TRB Adaptive Control Workshop 6

7 Detectors Needed Add SCATS 16 x 6 detectors (loop or video) in all approach lanes at four intersections (i.e. the major intersections) i.e. 3 x 4 x 4 = 48 detectors Use existing detectors at minor intersections. Jan 7, 2001 TRB Adaptive Control Workshop 7

8 Communications Require 300 bps bandwidth to each intersection. Field master system means that there is at least two pairs running the length of the system, Best choice is to use SCATS Multidrop, provides ability to cluster up to 8 intersections using a two-wire line. Jan 7, 2001 TRB Adaptive Control Workshop 8

9 Communications Configuration Leased Line 1 Leased Line 2 Leased Line 3 Subsystem 1 Subsystem 2 Subsystem 3 Subsystem 4 Comms cluster 1 Comms cluster 2 Comms cluster 3 4 miles, 20 intersections Use existing pairs for interconnect Install three leased lines to connect to the three clusters. Leased lines connect to Central System. Jan 7, 2001 TRB Adaptive Control Workshop 9

10 Multidrop Arrangement Multidrop connects up to 8 controllers using one pair (i.e. two wire circuit), Arrangement is a daisy-chain Two-wire "leased line" to first controller in cluster Two-wire (twisted pair) Intersection Controllers Jan 7, 2001 TRB Adaptive Control Workshop 10

11 Local Controllers Controllers available for SCATS are: 170E with hardware/software modification for 170 cabinets, 2070 with SCATS controller software for 170 cabinets, 2070N with SCATS controller software for NEMA TS 1 or TS 2 type 2 cabinets. Jan 7, 2001 TRB Adaptive Control Workshop 11

12 Local Controllers Use Eagle 2070N Lite (i.e. without VME chassis) fitted with communications module, Minor cabinet changes two back panel links addition of D-connector panel at major intersections to connect detectors 9 to 12 Note : Can use 4-line, 8-line screen or no-screen configuration and portable hand held terminal or Notepad PC for user interface Jan 7, 2001 TRB Adaptive Control Workshop 12

13 Central Hardware/Software 300 Mhz PC with 64 Mb RAM Windows NT 4.0 Operating System, Serial Interface Units Digiboard C/X 16 serial interface with extra C/CON to provide 32 controller lines, OR Specialix RIO with two 16 port concentrators. SCATS software license for 17 to 32 intersections Jan 7, 2001 TRB Adaptive Control Workshop 13

14 Installation Cost Ranges 1 Data Detectors: 48 detectors at $ 750 each = $36,000 Develop system data (consulting) = $50,000 Communications Multidrop concentrators & modems, line isolation = $40,000 Jan 7, 2001 TRB Adaptive Control Workshop 14

15 Installation Cost Ranges 2 Controllers 20 Eagle 2070NL with SCATS software, 4 with D connector panels = $150,000 Central Hardware and Software Server class PC with serial I/O SCATS license for 17 to 32 intersections = $ 50,000 Grand Total $ 326,000 ($ 16,300 per Int..) Jan 7, 2001 TRB Adaptive Control Workshop 15

16 Comments Multidrop is expensive - will be replacing it with integrated point-to-multipoint communications system, 2070N controllers are still expensive - price expected to fall significantly in the future, SCATS license (standard size) provides for expansion to 12 more intersections. Jan 7, 2001 TRB Adaptive Control Workshop 16