A linear model for determining coordination of two adjacent signalized intersections
Purpose – Urban networks are usually divided into several open or closed sub‐networks. Signal coordination has been recognized as one of the most efficient methods of controlling sub‐networks that have independently optimized timing plans. However, coordinating adjacent intersections in a network is a basic prerequisite to optimizing signal‐timing plans for sub‐networks. This paper aims to develop a linear model to support decisions regarding coordination of adjacent signals.Design/methodology/approach – This paper aims to develop a linear model to support decisions regarding coordination of adjacent signals. The tests of this model which using the field data differ from those for calibration from various roadways, indicating that the model has transferability. Evaluations using microscopic simulation show that the model can objectively determine whether or not to interconnect adjacent signals depending on various traffic demands.Findings – The model was calibrated by stepwise regression analysis with a t...
A Network Partition Approach for MFD-Based Urban Transportation Network Model
Recent findings identified the scatter and shape of MFD (macroscopic fundamental diagram) is heavily influenced by the spatial distribution of link density in a road network. This implies that the concept of MFD can be utilized to divide a heterogeneous road network with different degrees of congestion into multiple homogeneous subnetworks. Considering the actual traffic data is usually incomplete and inaccurate while most traffic partition algorithms rely on the completeness of the data, we proposed a three-step partitioned algorithm called Iso-MB (Isoperimetric algorithm Merging Boundary adjustment) permitting of incompletely input data in this paper. The proposed algorithm was implemented and verified in a simulated urban transportation network. The existence of well-defined MFD in each subnetwork was revealed and discussed and the selection of stop parameter in the isoperimetric algorithm was explained and dissected. The effectiveness of the approach to the missing input data was also demonstrated and elaborated.
IDEAL STREET SPACING TABLES FOR BALANCED PROGRESSION
Analytical studies were conducted that combined existing progression formulas with new formulas to develop ideal street spacings for balanced progression. Ideal street spacings were developed for various combinations of design parameters, including single alternate progression, double alternate progression, cycle lengths from 30 to 120 seconds, speeds from 20 to 50 miles per hour, two phase and eight phase operation, lead-lag left turn phasing, and 50/50, 60/40, and 70/30 splits. The ideal street spacing data were verified using TRANSYT computer simulations, and a family of tables were developed for use by traffic engineering personnel in planning and designing new arterial systems. The tables can also be used to assist in designing new arterial systems. The tables can also be used to assist in designing traffic control systems to improve safety and efficiency on existing arterial systems.