Interchange Design, Safety, and Operations
Diverging Diamond Interchange
NCHRP Project 03-113: Guidance for Traffic Signals at Diverging Diamond Interchanges and Adjacent Intersections. The objective of this research was to identify, review, and evaluate the geometric design features and the associated safety and operational performance of in-service diverging diamond interchanges (DDIs). A crash modification function was developed using data for 26 DDIs. The findings and recommendations from this development are documented in Working Paper 1. PAPER
Interchange Ramp Design Guidelines
TxDOT Report 0-4538-3: Recommended Ramp Design Procedures for Facilities without Frontage Roads. J. Bonneson, K. Zimmerman, C. Messer, and M. Wooldridge. This report describes design procedures for interchange ramps on facilities without frontage roads. The procedures described include models for evaluating the operational and safety benefits of alternative ramp configurations. They also include guidelines for designing ramps of adequate length, appropriate horizontal and vertical curvature, and reasonable accommodation of larger vehicles. REPORT SPREADSHEET
TxDOT Report 0-4538-2: Development of Ramp Design Procedures for Facilities Without Frontage Roads. J. Bonneson, K. Zimmerman, C. Messer, D. Lord, and M. Wooldridge. The objective of the research is to develop recommended design procedures for interchange ramps on facilities without frontage roads. This report documents the research conducted to develop the ramp design guidelines. REPORT
TxDOT Report 0-4538-1: Review and Evaluation of Interchange Ramp Design Considerations for Facilities Without Frontage Roads. J. Bonneson, K. Zimmerman, and M. Jacobson. This report describes the findings from the first year of a two-year project. Current ramp design practices were reviewed, and the operational features of interchange ramps in non-frontage-road settings were evaluated. The findings from the evaluation of the field and simulation data indicate that a rational approach to interchange type selection and operational evaluation is feasible using the critical movement analysis approach. REPORT
Single-Point Urban Interchange
ADOT Report 501: Evaluation of Operational Efficiencies, Cost, and Accident Experience of Four-Phase Single-Point Urban Interchanges. J. Lee, T. Larwin, B. Kidd, and J. Bonneson. This report compared the operational and safety performance of the single-point urban interchange (SPUI) and the tight urban diamond interchange. The findings from this evaluation were used to develop recommended changes to the interchange form selection process. Recommended SPUI design and operations guidelines were developed. REPORT
Bridge Size and Clearance Time of the Single-Point Urban Interchange. J. Bonneson. This paper describes a procedure for quantifying the impact of various SPUI design elements on signal phase clearance time and right-of-way requirements. The procedure is automated in an accompanying spreadsheet. PAPER SPREADSHEET
Interchange Operation
Report TTI/ITS RCE-01/01: Actuated Controller Settings for the Diamond Interchange with Three-phase Operation. J. Bonneson, and S. Lee. This project evaluated alternative control sequences and settings for the actuated, three-phase diamond interchange. The settings evaluated include the minimum green interval, maximum green interval, and passage time. The objective of this project was to develop guidelines for establishing controller settings that would yield low-delay operation. REPORT
NCHRP Project 3-47: Capacity Analysis of Interchange Ramp Terminals, Final Report. C. Messer and J. Bonneson. This research project was conducted to develop and validate a methodology for determining capacity and level of service at signalized interchanges. The researchers developed saturation flow rate adjustment factors for turn radius, traffic pressure, and distance to downstream queue. A model was developed for quantifying the effect of cyclic queue spillback and demand starvation on ramp terminal operation. REPORT
Report FHWA-NE-96-P493: Pedestrian Facilities at Interchanges. G. Zeidan, J. Bonneson, P. McCoy. The objective of this research was to develop design guidelines for pedestrian facilities at interchanges. The development was based on a review of the literature, a survey of state departments of transportation, and a number of field studies of pedestrian behavior at interchanges. The guidelines address the design and use of sidewalks, crossings, traffic control devices, and illumination for pedestrian facilities at interchanges. REPORT
Interchange Justification
Report TRP-02-25-91: Interchange vs. At-Grade Intersection on Rural Expressways. J. Bonneson and P. McCoy. This research compared the economic benefits and costs of replacing a two-way STOP-controlled intersection with either a signalized intersection or a full diamond interchange with STOP-controlled off-ramps. The benefit-cost methodology was applied to the two-way STOP-controlled intersection and the full diamond interchange to obtain two threshold values of base year (i.e., opening year) daily traffic demand. These two values correspond to benefit-cost ratios of 1.0 and 2.0. Major and Minor road annual average daily traffic volumes were identified where an interchange is more cost-effective than an intersection. REPORT