This paper proposes two sensible approaches that may be potentially implemented in practice to determine pricing strategies for operating managed toll lanes. The tolls vary dynamically in response to real-time traffic conditions in order to provide a superior free-flow travel service to the users of the toll lanes while maximizing the freeway’s throughput. Simulation experiments are conducted to validate and compare the proposed approaches.

Results from a finite-element program developed in the commercial code Plaxis were compared to those from an instrumented thin flexible pavement containing multiple test sections. The model has performed reasonably well under the limited environmental conditions encountered to date. Horizontal strain in the longitudinal direction of the asphalt concrete, vertical pressure in the crushed stone, and vertical pressure in the compacted subgrade were measured for 2,100 passes of loaded single axle dump truck traffic to compare to the values calculated in the model. Necessary inputs were determined using a rigorous laboratory testing program, alongside field data from over 500 drops of a falling weight deflectometer. Key features of the finite-element model include stationary transient loading and nonlinear stress dependent characterization of the compacted subgrade and crushed stone. Highlights of the results include the model moderately overpredicted unbound layer stresses, while overpredicting asphalt strain in some cases and underpredicting it in other cases, Discussion of the full scale test section, project scope, finite-element model development, and the results have been included in the body of the paper.

The interactive highway safety design model (IHSDM) is a suite of software analysis tools used to evaluate safety and operational effects of geometric design on two-lane rural highways. IHSDM checks existing or proposed two-lane highway designs against relevant design policy values and provides estimates of a design’s expected safety and operational performance. This paper describes efforts to apply IHSDM to two existing rural roadways (one an arterial and the other a collector) in Pennsylvania and to compare the crash prediction and speed profile results to observed speed and crash data for these same two roadway segments. When considering both case study roadways together, the use of site-specific crash history data, adjusted using the empirical Bayes procedure, and a county-level calibration factor, produced crash frequency predictions that most closely matched the observed crash frequencies. The design consistency module output on the arterial roadway closely matched the observed speeds. On the collector roadway, the predicted and observed speeds did not match closely, thus, underscoring the need to expand the design consistency module capabilities to consider low-speed, complex alignments.

In three-dimensional (3D) alignments, some road geometric parameters, such as vertical curve type (crest or sag), can cause drivers to have visual illusions in perceiving the horizontal curvature that may result in erroneous decisions. Road curvature estimation is usually made based on the perspective-view (PV) information. It is hypothesized that drivers can estimate road curvature visually based on the openness magnitude of the inside edge lines which appear to the drivers as parabolas or hyperbolas. This paper further develops the PV concept and validates it using the published results of driver perceptions of 3D alignments. The analysis shows that there are statistically good relationships between the ratio of the 3D perspective radii of the crest (or sag) and flat horizontal curves, and driver perceptions. Preliminary criteria for the design of 3D alignments based on driver perceptions are presented. The PV method provides a means of incorporating driver perception into geometric design, and therefore should be of interest to highway designers and researchers.