1. Signalized Intersections
History and Evolution
Role of Software

2. Signalized Intersections
Procedures
1950, 1965, 1985, 1994, 1997, 2000 & 2010
Concept of Capacity to Phase Duration Model
Software
Earlier, Engine, Current and Future Versions
Apple IIe to DOS, Windows and Spreadsheets

3. Signalized Intersections
Procedures – 1950 HCM
First Edition
Only 147 Pages
Capacity Concept
Basic, Possible and Practical
Adjustment Factors
Street Width, Parking, Commercial Vehicles, Buses, Left and Right Turns, Green/Cycle Ratio

4. Signalized Intersections
Procedures – 1965 HCM
Approach Based
Service Volumes
Level of Service
Concept Introduced
Based on Load Factors
Critical Movement Analysis
TRB Circular 212 (1980)

5. Signalized Intersections
Procedures – 1985 HCM
Saturation Flow Rate
Lost Time Introduced
Flow Ratio and Xc
Stopped Delay for Level of Service
Lane-Group-Based Delay and LOS
Volume/Capacity Ratio less than 1.2
Planning Level Analysis Introduced

6. Signalized Intersections
Procedures – 1994 Update
SigSub Enhancements
Not Funded Research
Progression Factor
Uniform Delay Only
Protected-Permitted Left-Turn Model
Major Enhancement with New Adjustments
Ideal Saturation Flow Rate to 1900

7. Signalized Intersections
Procedures – 1997 Update
Delay Equation Modified
Oversaturation Conditions
Multiple-Period Analysis
Variable Analysis Period
Filtering/Metering (I) and Calibration (k) Factors
Lane Utilization from Flow to Saturation Flow
Level of Service using Total Control Delay

8. Signalized Intersections
Procedures – HCM 2000
Back-of-Queue
Several Percentiles
Queue Storage Ratio
Saturation Flow Rate Adjustments
Added Pedestrian for Permitted Left Turns
Introduced Bicycle Effects on Right Turns
Consolidated Worksheets Updated

9. Signalized Intersections
Procedures – HCM 2010
Phase Duration Model
Shared-Lane Model
Dual-Ring (NEMA) Phasing
Incremental Queue Accumulation (IQA)
Alternative Tool Analysis Guidance
Pedestrian and Bicycle Level of Service

10. Signalized Intersections
Software – Earlier Versions
DOS Applications for Green Screens
Automated Calculations, From Apple IIe to DOS
Software Provided for Complex Solutions
Efficient and Accurate for Practitioner Application
Operating System and Hardware Advances
DOS to Windows with Graphics and the Mouse
Full Color, More Speed and On-Board Help

11. Signalized Intersections
Software – Current Versions
Oversaturation using Multiple Periods
Unmet Demand, Initial Queue, d3 Delay
Fully-, Semi- and Coordinated-Actuated
Phase Duration, NEMA Phasing, Shared Lanes
Multiple Signals in Urban Streets
Flow Profile, Access Points, Balanced Flows
Interchange Ramp Terminals

12. Signalized Intersections
Software – Current Versions
Challenge to Implement New Models
Complex and Iterative Models Included
Interactive Committee Assistance Needed
Challenge to Integrate Methodologies
Signalized Intersections – ATDM
Urban Streets – Reliability
Interchange Ramp – Alternative Terminals Intersections

13. Signalized Intersections
Software – Future Versions
Potential Improvements
Integration – Among Chapters and Tools
Urban Streets and Freeway Facilities
Import – Multiple Period and Annual Data
Wizards – Guiding Complex Data Entry
Architecture – Scenarios and Iterations
Windows 8 – Touch Screens and Apps

14. Signalized Intersections
History and Evolution
Role of Software