Blogs & App Demos

Maryland Top 20 Busiest Roads (2009 - 2018)
A racing bar chart, data from SHA Traffic Monitoring Program
North America Top 20 Metropolitan areas Daily Traffic (Sunday - Saturday) by Google Map
Typical traffic video
2009 MUTCD Mobile app as a pocket reference
Available in iOS and Android, browse and easily search
VISSIM Vehicle Trajectory Visualized for fun
VISSIM Vehicle Trajectory/Trails Visualized using Processing
VAPPad - a VAP file editor with modern IDE features & Introduction to VAP
Live errors, auto completion, auto formatting, function quick info and parameter info, code folding, delimiter matching, word highlighting etc.
Free Web app Comparing Wiedemann 74 and 99 car following model & Replicating Dissipation of stop-and-go waves via control of autonomous vehicles
Toy with W74 & W99 parameters and autonomous vehicle control to improve traffic flow
Free Web based VISSIM Viewer
Free lightweight web based viewer to browse your local VISSIM inpx files
Free Web app Simulating Stochastic Vehicle Arrivals - VISSIM Stochastic vs Exact Inputs
Simulate stochastic vehicle arrivals from negative exponential distributions using Mersenne Twister 19937 algorithm and compare VISSIM Stochastic vs Exact Inputs
Free Web based OD Estimation/Balancing tool
OD Matrix estimation/correction through Bi-level Optimization Algorithm - bush(origin)-based user equilibrium assignment and sensitivity analysis; Maximum Entropy Matrix Estimation (ME2) by proportional assignment, for no congestion in the network or no parallel path exists
Free Web based Intersection HCM 2010 LOS (work in progress)
Intersection LOS reporting following HCM 2010 procedure (compute engine V 07-12)
Free Web based GIS using leafletjs - Draw - Switch Layers - Geolocation (work in progress)
Draw Line/Polygon over Google Maps - Switch Layers - Geolocation
Free Web app Comparing Static Traffic Equilibrium Assignment Algorithm - Frank–Wolfe vs. Algorithm B
Comparing Static Traffic Equilibrium Assignment by Frank–Wolfe method against Robert B. Dial's Algorithm B, Frank-Wolfe is easier to code, consumes least memory, but converges slowly
Free Web app Using Doubly Constrained Growth Factor a.k.a. Furness or Fratar method
Furness/Fratar method to adjust OD matrix by Row/Column targets - example is from Modelling Transport, 4th Edition by Juan de Dios Ortúzar, Luis G. Willumsen; Section 5.2.3 Table 5.6 and Table 5.7 on page 181
TransCAD Caliper Script Editor - CasPad
  • Syntax highlighting, macro grouping, matching
  • A few days hack, using ANTLR generated parser to parse TransCAD script
  • Plan to add IntelliSense when having time
  • Newer version coming soon
HTML 5 canvas animation - based on The Nature of Code, rewritten in paper.js
Free (PC) traffic counter - JLCounter, iOS/Android version pending
  • Record Time-stamped data, PC based, written with Visual Basic 6, last update 2005
  • iOS/Android version under active development and coming soon

Commercial Support Available


VHelper is a VISSIM utility program created by me on my own spare time that can be used to increase productivity, for QA/QC and Visualization. It is well acclaimed and receives excellent reviews from our industry VISSIM experts from well-known firms such as CH2M Hill, HNTB and Kimley-Horn.

  • Productivity
    1. Create Static Routings by Reading OD Matrix text file (Support Multiple Time-Period and Link Specific, such as forbidding GP car to use HOV links)
    2. Create Vehicle Inputs & Vehicle Compositions from text file (Support Multiple Time-Period as well)
    3. Combine Static Routings
    4. Create a series of Data Collection Points along a User Defined Path
    5. Find & Replace & Filter Routes with a string of Link Connector IDs
    6. Manipulate Lane Closures along a User Defined Path (a string of Link Connector IDs)
  • Visualization
    1. Calculate Demand Volume by Segment, Label them & Display Volume Bandwidth Map
    2. Calculate Link Desired Speed & Display in User Specified Color
    3. Visualize Speed Contour Heat Map & Freeway Diagrams from Data Collection Measurement with a few clicks
    4. Visualize Max/Average Queues from Queue Counter Output
    5. Visualize Max/Average Queues from Node Evaluation Output files
    6. Build Node Diagrams - width additional bells and whistles such as Sankey diagram for Volume, Gauge for Delay
    7. Display Links/Connectors in Centerline, Normal, or Lane Schematic mode
    8. Display Links/Connectors colors by Link Type, Gray or Speed
  • QA/QC
    1. Check Static Routings by Calculate Demand Volume and Compare against Counts
    2. Check Desired Speed Decision
    3. Check Lane Change Distance
    4. Check Signal Heads Placement
MUTCD/SHS Mobile app
MUTCD/SHS Mobile app (both iOS and Android versions available)
Traffic Jam Hero - A Mobile Traffic simulation game
Under active development, coming soon