1. Technical Field
This invention relates to traffic control devices, and in particular to portable devices for selectively hindering the movement of vehicles in two opposing directions through a control point.
2. Related Art
Regulating the flow of vehicular traffic through particular areas is often required to prevent unauthorized ingress to or egress from restricted areas. For example, access to a toll road or parking lot may be blocked unless and until a payment is made, a ticket is obtained, or proper credentials are displayed. Alternatively, departure from these areas may be blocked unless and until a payment is made or proper credentials are displayed. Law enforcement personnel may also block vehicular access to or through certain areas for specific purposes, such as the establishment of a road block to apprehend a suspect.
All of these methods of traffic control typically involve the use of a physical barrier placed at a certain control point that blocks the flow of traffic through the control point so long as the conditions for access through the control point are not met. For example, a toll booth may be placed along an access ramp leading to a toll road such that anyone desiring access to the toll road must drive up to the toll booth. At the toll booth, a gate arm may block the access ramp until a toll is paid, at which time the gate arm raises and permits access to the toll road.
It is often desirable to use a traffic control device that damages the tires of an unauthorized vehicle as it drives through a control point. U.S. Pat. No. 5,733,063 granted to Bailey et al. discloses an example of one such device. This device has a plurality of rotationally mounted levers extending upwardly from a base housing permanently embedded flush with the road surface. The levers rotate into the base housing below the road surface when contacted by a vehicle tire moving in one direction, thus permitting traffic flow in that direction. When contacted by a vehicle tire moving in the opposite direction, however, the levers rotate a hidden blade upward into the tire. The device is therefore uni-directional, permitting traffic flow in one direction and obstructing traffic flow in the opposite direction. A hydraulic system may additionally be actuated to retract the levers underneath the road surface, thereby permitting traffic flow in both directions. The Bailey device is not designed to allow for the selective obstruction of the flow of traffic. That is, the Bailey device cannot be controlled to dynamically change the direction of allowed traffic flow—it only works for one pre-determined direction. Likewise, the Bailey device cannot allow traffic flow in both directions, nor can it simultaneously prohibit the flow of traffic in both directions. In order to achieve such versatility, two such devices must be installed adjacent to one another, back-to-back, as suggested by Bailey et al. The cost and/or space needed for installing two devices rather than one may make installation of a means for multidirectional traffic control infeasible for certain applications. This device also is designed to be permanently embedded in the roadway. Any modification to such a permanently installed traffic control device, such as a lengthening of the effective area covered by the device, might be time-consuming and cost-prohibitive.
Therefore, there is a need for a multidirectional traffic control device housed in a single unit. There is also a need for a portable traffic control device that is not designed to be permanently embedded within a roadway. Additionally, there is a need for a traffic control device that is easy to use and is modular to permit easy and inexpensive extension of the effective area covered by the device.