GENERAL FEATURES

HCS™ > TRANSYT-7F™General Features
TRANSYT-7F features genetic algorithm optimization of cycle length, phasing sequence, splits, and offsets. The genetic algorithm has the ability to avoid becoming trapped in a “local optimum” solution, and is designed to locate the “global optimum” solution. The hill-climb optimization option is also available within the software, for the purpose of quickly obtaining a reasonable and effective timing plan. The genetic algorithm allows advanced searches that the hill-climb method can’t handle, such as phasing sequence optimization, multi-period optimization, grouped node optimization, uncoordinated optimization, and direct CORSIM optimization.

The genetic algorithm is a random guided search, capable of intelligently tracking down the global optimum solution. As with the human race, the weakest candidates are eliminated from the gene pool, and each successive generation of individuals contains stronger and stronger characteristics. It’s survival of the fittest, and the unique processes of crossover and mutation conspire to keep the species as strong as possible.

The genetic algorithm tends to require longer running times on the computer when compared to other optimization techniques. However, the genetic algorithm can be easily customized by specifying the “number of generations”. To quickly obtain a reasonable timing plan, specify a small number of generations. To obtain the global optimum solution, specify a large number of generations.

transyt-7f_GeneticAlgorithm

The TRANSYT-7F Map View currently contains the following features:

  • Link curvature
  • Printing support
  • Dynamic scrolling of the map
  • Drag and drop nodes on the map
  • Zoom in, zoom out, pan, show all
  • Graphical add/delete of links/nodes
  • Select and move entire groups of nodes
  • User-friendly bitmap background scaling
  • Right-click on nodes to edit their properties
  • Nine available map background colors to choose from
  • Progression routes drawn with bold lines for emphasis
  • Right-click on a node and “View Report” for this node
  • “Undo” feature for canceling recent changes to the map
  • Right-click on a node and “View HCS results for this node”
  • View intersection names by moving the mouse pointer over a node
  • Right-click on a node and “View CORSIM animation for this node”
  • Define progression routes automatically by selecting a group of nodes
  • Ability to underlay user-supplied bitmap backgrounds and aerial photos
  • Display level of service on the map for TRANSYT, CORSIM, and HCS
  • Graphical coding of progression routes, arterial weighting factors, and route titles
  • Copy-and-paste intersections, to avoid re-coding lane configuration, volumes, and timings
  • Link lengths, free-flow speeds, link names, gridlines, intersection delay and LOS on the map

transyt-7f_MapView

TRANSYT-7F offers CORSIM post-processing, such that the engineer can summarize results from one or more CORSIM runs (with varying random number seeds). Following a CORSIM post-processing run, TRANSYT-7F produces a summary text report that contains NETSIM link results, NETSIM node results, and CORSIM network-wide results.  TRANSYT-7F can also provide a one-page formatted report for NETSIM intersections. The summary text report and formatted report both provide intersection-wide control delay and level of service. The formatted report also provides approach-specific control delay and level of service. The Map View can also be used to graphically display NETSIM control delay and level of service. The interactive time-space diagram can be used to observe and design bandwidth in NETSIM.

TRANSYT-7F also offers “direct” CORSIM optimization (also known as “microscopic” optimization) of cycle length, splits, and offsets, using the genetic algorithm. With direct CORSIM optimization, TRANSYT-7F applies the genetic algorithm to supply timing plan candidates, and CORSIM evaluates them through its own simulation. The end result is a new copy of the original CORSIM input (*.TRF) file containing the optimized timing plan, plus the availability of TRAFVU animation for the optimized timing plan. TRANSYT-7F will minimize NETSIM control delay by default, but the user can choose among nine different CORSIM MOEs to be used as the optimization objective function.

Because direct CORSIM optimization is accomplished via genetic algorithm, this ensures that the user’s original timing plan will be improved upon, assuming that a better timing plan exists. In addition, direct CORSIM optimization can be easily applied by anyone, because there is no learning curve.  Simply launch TRANSYT-7F, load any TRF file, select one of the nine available optimization objective functions, and click on “Run”. This alone achieves a better CORSIM timing plan than any other program or process. Once the user gains experience with choosing non-default genetic algorithm parameters (e.g., mutation probability, population size, etc.), the optimization process can become even more efficient and effective.All pre-timed, fully-actuated, and semi-actuated intersections in CORSIM can be optimized directly.  The current version of TRANSYT-7F does not support direct CORSIM phasing sequence optimization, although this could be accomplished by macroscopic (TRANSYT-based) optimization.  If an optimized phasing sequence is coded or exported into a TRF file, the overall timing plan could then be further improved via direct CORSIM optimization of cycle length, splits, and offsets.  Note that direct CORSIM optimization may not be practical for large TRF files, due to the CPU running time required for microscopic simulation.

The TRANSYT-7F Timing View screen allows easy coding of complex timing plans, including one-touch coding of entire phasing sequences.  The Dual-Ring Timing screen allows 8-phase NEMA coding of timing plans.

transyt-7f_TimingView1

transyt-7f_TimingView2

TRANSYT-7F has the ability to import existing CORSIM input files. However, if no CORSIM file exists yet, TRANSYT-7F also offers “one-touch” CORSIM animation (i.e., CORSIM file export). This pre-processing feature creates NETSIM networks from scratch, and is available for either the entire TRANSYT-7F network, or for individual intersections. To create a CORSIM input file that reflects an entire TRANSYT-7F network, click on the “CORSIM Animation” icon on the TRANSYT-7F toolbar, or select “File > CORSIM > View animation for this network”. To create a CORSIM input file that reflects one intersection only, simply right-click on an intersection in the Map View, and select “CORSIM > View animation for this node”. If the user doesn’t wish to view animation, CORSIM input and/or output files can optionally be generated without launching animation.

It is also possible to right-click on an intersection in the Map View and view HCS results for that intersection. If the HCS file already exists, it will be opened automatically by HCS+. If not, an HCS file will be created instantly by a data conversion program, and this brand-new file will be opened automatically by HCS+. Timing plans can also be exported from TRANSYT-7F to HCS within the Timing View screen.
transyt-7f_OneTouch
The interactive time-space diagram screen allows the user to view a graphical representation of signal progression along the major street(s). The screen can display progression bands in the forward direction, reverse direction, or both. The time-space diagram also offers manual adjustment of offsets and progression bands, ability to draw “cumulative” progression bands, graphical adjustment of free-flow speed, bandwidth efficiency and attainability, and is sizable to offer a full-screen view.

transyt-7f_Time-SpaceDiagram

TRANSYT-7F can now import any CORSIM file that contains a signalized intersection. The following CORSIM data can now be imported: pre-timed intersections, semi-actuated intersections, fully-actuated intersections, multiple time period data files, and two-way stop (TWSC) intersections. The user can choose whether or not to import fully-actuated intersections and TWSC intersections. After importing a CORSIM file, TRANSYT-7F provides numerous helpful features for further analysis including:

  • direct CORSIM optimization
  • conversion to macroscopic TRANSYT analysis
  • post-processing of CORSIM’s own simulation results
  • time-space diagrams that reflect CORSIM’s own signal timing
  • formatted reports that reflect CORSIM’s own simulation results
  • superimpose CORSIM’s own intersection-wide control delay and level of service on the Map View

Highway Capacity Software (HCS) data files can now be loaded directly into TRANSYT-7F, provided that they are available in *.XHS (XML for HCS+ Signals) format, or *.XHI (XML for HCS+ Interchanges) format. There are two possible methods for loading HCS files into TRANSYT-7F.  The first method involves simply loading an HCS file by selecting File > Open from TRANSYT-7F. This will automatically generate a corresponding TRANSYT-7F data file for the HCS intersection(s). The second method involves appending HCS intersection data to an existing TRANSYT-7F (*.TIN) input file. First, it is necessary to open the existing TIN file with TRANSYT-7F.  Next, it is necessary to select File > Open and open an existing file of type *.XHS, which will enable the “New Node Number” dialog box. This is the node number that will be used inside the TIN file. After selecting the new node number, the new data will automatically be added to the TIN file.

transyt-7f_ImportCORSIM

The Lane Configuration screen in TRANSYT-7F allows easy coding of lane channelizations, and provides support for peak hour factor (PHF) coding. Volume adjustments and complicated link number assignments are handled automatically. Radio buttons are available to simplify the lane-by-lane analysis process, in the event that a lane-by-lane analysis is desired. It is possible to select Edit > Lanes > Intersection View, to geometrically display four approaches on one large screen. It is also possible to display a separate screen that focuses on one approach by selecting Edit > Lanes > Northbound, Southbound, Eastbound, or Westbound. The Edit > Lanes > Intersection View option is illustrated below.

transyt-7f_LaneConfig

Highly unequal lane utilizations are modeled more accurately when a link is defined to represent each individual lane. For special network locations in which traffic utilization of a given lane is significantly different from other lanes in the same lane group, “lane-by-lane” modeling becomes necessary for achieving realistic results. The Lane Configuration screen allows easy specification of lane-by-lane analysis, and the Traffic screen allows specification of volumes and saturation flow rates for each individual lane.
TRANSYT contains two models for analysis of traffic-actuated control. The first model (target degree of saturation model) is a design model, intended to locate the actuated phase times that would optimize the traffic network. The second model (actuated estimation model) is an evaluation model, intended to evaluate existing conditions. The target degree of saturation model allows actuated phases to operate in the efficient 80%-90% degree of saturation range, while allocating left-over green time to the major street. The actuated estimation model is typically used to compute phase times that are likely to materialize in the field, based on user-specified maximum green and force-off settings.
TRANSYT-7F provides three types of reports, for visualization and printing of data. The lengthy “legacy report” provides extensive output data for the macroscopic TRANSYT simulation model. One-page summary text reports are available for intersections, routes, or for the entire network. One-page formatted reports are available for TRANSYT and CORSIM intersections in both single-ring and dual-ring timing formats. The one-page text report and formatted report also contain agency information, and analysis-specific information. Graphical input/output screens (e.g., Map View, Profile View, Lane Configuration, Timing View, Time-Space Diagram) can be sent to the printer or to an image file, if desired.

transyt-7f_OutputReports

TRANSYT-7F contains a powerful macroscopic simulation engine that allows for detailed analysis and optimization of platoon progression, actuated control, and queue spillback. The engineer can view flow profiles and queue length profiles for any traffic movement, any cycle length, and any time period.

transyt-7f_MacroscopicSimulation

The saturation flow rate screen provides quick and easy estimation of adjusted saturation flow rates. Adjustment factors are computed and displayed in accordance with Highway Capacity Manual (HCM2000) procedures.

transyt-7f_SaturationFlowRate