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Urban Traffic Operations/SMART-SIGNAL Project – Wikibooks, open books for an open world

The SMART-SIGNAL (Systematic Monitoring of Arterial Highway Site visitors and SIGNAL) system, developed by the College of Minnesota, presents an simply implementable method to gather and archive steady and high-resolution site visitors knowledge on signalized arterials (Liu et al., 2008). On this system, a whole historical past of site visitors sign management, together with all automobile actuation occasions and sign part change occasions, is archived and saved. Primarily based on the event-based knowledge, arterial efficiency measures, equivalent to arterial journey time, intersection queue size, and degree of service, are produced. The SMART-SIGNAL system has been put in on 11 intersections alongside France Avenue in Hennepin County, Minnesota, and 6 intersections alongside Trunk Freeway 55, Minnesota, since February 2007. Occasion-based site visitors knowledge are being collected in a 24/7 mode after which archived in a database system, thus yielding an incredible quantity of subject knowledge obtainable for analysis. This chapter will briefly introduce the system structure, knowledge assortment {hardware}, and knowledge processing process of the SMART-SIGNAL.

System Structure[edit]

As illustrated within the following determine, the SMART-SIGNAL system has three main elements, knowledge assortment, efficiency measurements, and efficiency presentation via person interfaces. The info assortment element collects excessive decision uncooked knowledge straight from the sphere on an event-by-event foundation. Sign part change occasions and vehicle-detector actuation occasions are acquired individually from knowledge assortment items positioned in site visitors sign cupboards. The info are recorded in each day log information and despatched to an information server on the grasp cupboard by serial port communication. The each day log information are lastly transmitted to a database positioned on the Minnesota Transportation Observatory (MTO) lab on the College of Minnesota via the Digital Subscriber Line (DSL) or wi-fi communication. The second element of the SMART-SIGNAL system is efficiency measure calculation utilizing the field-collected knowledge. Evaluation of the saved knowledge log information yields a set of efficiency measures, one covers intersection degree measures (e.g. queue size) and a second associated to arterial degree measures (e.g. journey time). As soon as all efficiency measures have been derived from the uncooked knowledge, the outcomes are made accessible to quite a lot of customers.

SMART-SIGNAL System Structure

Information Assortment Unit[edit]

The important thing component of the SMART-SIGNAL is the info assortment unit, which consists of an industrial PC and an information acquisition card. At every intersection, an industrial PC with an information acquisition card is put in, and occasion knowledge collected at every intersection is transmitted to the info server within the grasp controller cupboard via the present communication line (on this case, spare twisted pair) between signalized intersections. The info acquisition playing cards (PCI-6511 from Nationwide Devices (2006)) used within the SMART-SIGNAL system, as proven in Determine 2 2a, have 64 enter channels. If the entire variety of detector inputs and sign phases for one intersection exceed 64, an extra knowledge acquisition card must be put in. A terminal field is used so as to restrict the enter direct present (DC) to a protected vary and set up the connection between the info acquisition card and again panel of the site visitors cupboard, as proven in Determine 2 2b. The terminal field permits digital voltage adjustments on the again panel, which point out totally different site visitors occasions within the subject, to be captured by the info acquisition card put in within the industrial pc. A site visitors occasion recorder software program program, developed utilizing the Microsoft Visible C# program, runs on the commercial pc within the subject to document the occasions (for instance, a part 1 inexperienced change from “ON” to “OFF”) right into a log file.

Demonstration of the Site visitors Information Assortment Parts

Information communication between two controller cupboards is finished utilizing the present twisted pair communication traces. A protocol of RS-485 is used to transmit knowledge and synchronize time between cupboards (B&B Electronics, 2007). After the info within the native cupboards is transferred to the grasp cupboard, DSL or a wi-fi unit put in within the grasp cupboard is used to ship the info again to the database positioned within the MTO.

A pattern of knowledge is proven within the determine. Every logged occasion begins with a time stamp that features the date, hour, minute, second and millisecond based mostly on the pc system time, adopted by several types of occasion knowledge together with part adjustments, detector actuation and pedestrian calls. An entire historical past of site visitors sign occasions is thus recorded.

Information Processing Process[edit]

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