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Transportation engineers are facing great challenges in meeting the mobility demands of an increasing population. As traffic demands continue to rise at many highway junctions, motorists, pedestrians, and bicyclists all experience longer delays and greater safety risks. Today's traffic problems are very complicated, and conventional intersection designs are often found to be insufficient to alleviate them. As a result, various innovative intersection designs are being investigated and implemented to mitigate or solve these complex problems.
This paper introduces and examines a new interchange configuration created by the author, referred to as the Double Offset-T Interchange (DOTI). The DOTI is an innovative geometric design and a potential solution for improving operations at highway junctions. It achieves this by eliminating one of the three traffic-signal phases of the conventional diamond interchange. Effectively, this adds more "green time" to the cycle for all vehicles by reducing the total amount of "lost time."
Although the DOTI shares some common aspects with other alternative intersection configurations, it has several novel characteristics not rendered by any other design. By using a unique configuration of offsetting the off-ramps at a distance from the on-ramps, conflicts between different left-turn movements are removed from the intersections. To mitigate the DOTI's right-of-way requirements, the tapers of the left turn lanes for traffic turning left onto the on-ramps is positioned in a way such that left turns made from the off-ramp cross it. The design could also be modified by providing indirect median turns for the left-turning vehicles on the cross road, which reduces the interchange's right-of-way requirements. No research on this particular treatment is conducted in this paper.
Description and Geometric Design
Figure 1 shows the general layout of a DOTI. Its most distinguishing design feature is the offset of the off-ramps from the on-ramps. The offset , which is 150 to 250 feet in length, removes conflicts between the paths of vehicles turning to and from the ramps. As a result, all turning movements can be made simultaneously in a single signal phase.. The distance between the terminals of the off-ramps is 400 to 500 feet.
Dual left-turn lanes are provided on both the cross road and off-ramps. The left-turn storage requirements for length are dependent upon site-specific conditions and traffic flow demands. Curve...