Using Naturalistic Driving Study Data to Evaluate the Effects of Intersection Balance on Driver Behavior at Partial Cloverleaf Interchange Terminals

Past studies showed that poor intersection balances at partial cloverleaf (parclo) interchange terminals significantly impact traffic safety and sight distance of drivers making left turns to entrance ramps. Some state traffic agencies have recommended a “balance” guideline that the length between the left-turn stop line on crossroads to the middle of the intersection should not be greater than 60% of the entire length of the intersection. However, a scarcity of research exists on how the balance of an intersection affects driver behavior, which has been identified as a critical contributing factor to intersection-related crashes. This study utilizes the Naturalistic Driving Study (NDS) data to evaluate the effects of intersection balance on driver behavior at parclo interchange terminals for proof-of-concept. A small but representative data sample was collected from the second Strategic Highway Research Program’s (SHRP 2) NDS dataset. It demonstrates statistical characteristics and overall trends of driver speed, acceleration/deceleration rates, and risk perception with the changing of intersection balances. Conclusions provide guidance on optimal intersection balance design that may help drivers make smoother and safer transitions from crossroads to entrance ramps at parclo interchange terminals.

Design of an Experimental Tensegrity Pedestrian Bridge

This paper presents the design of an experimental tensegrity pedestrian bridge. The structure is designed as a permanent three-span bridge with spans of 105 m. The bridge has two entrance ramps, three ground supports and one water support. The main structure of the bridge is designed as a light transparent structure based on the tensegrity principle using membranes.

Viewing Ground-Mounted Diagrammatic Guide Signs Before Entrance Ramps at Night: Driver Eye Scanning Behavior

The driver eye scanning study is part of a larger study conducted for the Ohio Department of Transportation to evaluate the effectiveness of ground-mounted diagrammatic guide signs placed before entrance ramps at highway freeway interchanges. This nighttime study investigated driver eye scanning behavior while approaching ground-mounted diagrammatic guide signs placed before entrance ramps. Six highway-freeway interchanges were selected in the Greater Columbus, Ohio, area for placement of the diagrammatic signs in the field. Subjects were six unfamiliar drivers, between the ages of 22 to 42. Two diagrammatic signs were located at each of the six interchanges, .5 mi (805 m) and .25 mi (402 m) before the last point of the gore, where a driver can still gain access to the correct freeway entrance ramp. Driver eye scanning behavior measurements were recorded at night to determine if the presence of the diagrammatic signs elicited an excessive number of eye fixations or was visually distracting to the drivers or both. The results indicate that the diagrammatic signs are not looked at excessively often or excessively long. The average look numbers and average look duration times indicate a normal and reasonable level of information acquisition processing employed by the drivers. These values agree with those previously obtained for regular traffic signing determined in previous eye scanning studies. Ground-mounted diagrammatic signs on multilane arterials in advance of highway freeway interchanges were not demonstrated to unduly distract drivers and detrimentally affect a driver’s looking behavior.

Effectiveness of Ground-Mounted Diagrammatic Advance Guide Signs for Freeway Entrance Ramps

This study investigated the effectiveness of ground-mounted diagrammatic signs in the context of urban multilane arterials leading to freeways. Six highway-freeway interchanges were selected in the greater Columbus, Ohio, area for installation of the diagrammatic signs in the field. The primary measure of effectiveness was the distance at which unfamiliar drivers driving in the wrong lane changed lanes. A total of 21 and 19 test drivers unfamiliar with Columbus roads were recruited for an evaluation before and after installation of the diagrammatic guide signs. This evaluation with unfamiliar test drivers showed that drivers were able to execute a needed lane change earlier when diagrammatic signs were provided. Combining all six sites and looking at the 50th (377 m before, 819 m after) and 85th percentile (203 m before, 601 m after) lane change distances, an increase by a factor of 2.2 to 3.0 between the after and before condition was observed. In addition, a panel of 13 Ohio Department of Transportation and FHWA evaluators visited the six interchange sites and provided their input and opinions on the use of diagrammatic signs. The majority of the evaluators fully embraced the idea of diagrammatic signs. It is suggested that such signs should be used on multilane arterials in advance of highway–freeway interchanges in addition to preexisting guide signs (trailblazer assemblies), in cases in which the cost of overhead span-type sign bridges cannot be economically justified and additional advance guidance information to motorists is highly desirable.

Comparison of Tolling Strategies for Highway 407 in the Greater Toronto Area

Tolling strategies recently tested for Highway 407 in the Greater Toronto Area (GTA) are described and analyzed. The GTA is one of the fastest-growing urban areas in North America, with a population of about 5 million. Highway 407, a six-/four-lane freeway in the GTA, has been considered for many years as a relief for Highway 401. It is the busiest highway in North America and is used by more than 1 million vehicles per day. Highway 407 is being planned and constructed as a toll highway. Four strategies are compared. In the base strategy, the toll rate per kilometer is fixed and the value of the toll paid depends on the distance traveled on the highway. In Strategy 2, vehicles on Highway 407 are tolled on the entrance ramps as well as at some points on the highway (main “virtual” plazas). In Strategies 3 and 4, each driver has two choices. The first is to pay a toll depending on the distance traveled. The second is to pay a certain fixed toll once the driver crosses certain points on the highway (mainline plazas) and on the exit ramps. The strategies are compared from the points of view of the number of users, the vehicle-kilometers on the highway, the revenues, and the average toll paid. The GTA mathematical model, within the EMME/2 environment, is used. The mathematical model and the evaluation process are described.