BACKGROUND

In many major cities around the world, trip durations during peak traffic hours can be 5 to 10 times what they are in uncongested traffic. This results in significant additional costs in fuel, personal time, business productivity, and pollution. Congestion relief measures often take one of three forms:1) increase system capacity by building more roads,2) improve flows by adjusting signal timing, entry/exit controls, etc., or3) improve flows by reducing the number of vehicles in any given region, road, or lane.

The focus of the present disclosure is method 3—to increase flows by reducing the number of vehicles on the road (vehicle density). To understand the advantages of reducing vehicle density it's useful to look at the general relationship between vehicle density and overall traffic flow. The curve in the graph shown inFIG. 1is representative of how traffic density (vehicles per mile along a road) effects vehicle flow (vehicles per hour passing a point).

The intersecting straight lines show vehicle speed at the intersection with the curve (flow divided by density). The absolute numbers should not be taken too literally, but the shape generally holds true, and it shows both how inefficient highly congested traffic is at utilizing available road capacity and how drastically vehicle density must be reduced from worst case congestion levels of greater than 200 vehicles per mile per lane (26 feet per vehicle) to maximize flow.

The roughly triangular curve shows that starting from zero, as vehicles are added total flow increases because there are more vehicles travelling at a speed limited only by individual driving practices and traffic regulations. As density approaches the peak of the curve, vehicle speed starts to decline as drivers slow in response to the higher density, and total flow starts to level off. Past the peak, adding more vehicles becomes counterproductive, reducing both total flow and individual vehicle speeds. Notice that there is a wide range of densities around the peak where flow remains about the same despite significant reductions in speed. Perhaps an intuitive explanation for this is the tendency for drivers in heavy traffic to space themselves approximately a fixed time apart (e.g. 1.5 seconds) to allow for reaction time and stopping distance. That fixed time spacing results in a fixed flow rate over a broad range of speeds.

Given the shape of the curve, the ideal maximum density to operate at is probably a little before the peak (point A), where flows are near optimum and vehicle speeds are still close to that of free flowing traffic. Operating in that region of the curve might require reducing vehicles on the road to a small fraction (20-30%) of worst case congestion levels, but individual vehicle speeds can be 5-10 times faster.

Many methods and systems are currently in use to reduce vehicle density. Some are very direct, such as mandating days of the week when certain vehicle license numbers cannot be on the road, while others are more indirect, such as improvements in public transportation and encouraging carpools. A very common method is to use tolls and fees to increase the cost of using the road. If the costs are high enough, a segment of the population will choose a route or transportation means that avoids that cost.

A disadvantage of existing cost-driven methods, however, is that they place an uneven burden on the driving population based upon financial status. Those that can afford to pay the toll are able to take advantage of the less congested restricted routes and lanes, while those who cannot must deal with even higher traffic densities on whatever roads or lanes are left. In this sense, they are not income neutral or fair. Also, because of this affordability constraint, their demand reduction effects help, but often fall far short of what would be necessary to maximize traffic flow efficiencies in highly oversaturated road systems.

Rather than organizing and managing the demand to actively and directly control traffic density, nearly all other congestion reduction methods in use in places like Singapore, London, and Stockholm use demand reduction (i.e., use some other transportation method, go some other time, or don't go at all) as their primary target, and do so indirectly through cost disincentives.

SUMMARY OF THE DESCRIPTION

The present disclosure generally relates to methods and systems to manage vehicle traffic density on one or more roads in a transportation system by controlling road access via one or more of: permissions, tolls, fees, and penalties. Control can be managed in real-time based upon demand, and permissions and fees are in one embodiment specific to individual vehicles requesting access. Centralized software algorithms can manage access permissions in a way, in one embodiment, that prevents excessive traffic demand from reducing traffic flows below optimum levels, thereby maximizing (or at least improving) road capacity and minimizing (or at least improving) travel times.

A traffic management system can be implemented in a variety of different embodiments using existing infrastructure (e.g. cameras on roads) or using new infrastructure or equipment (e.g. enforcement sensors mounted on one or more roads). In one embodiment, a method to operate a managed traffic system can include: receiving a request from a user to travel in a vehicle (e.g. a user's car) having a vehicle identifier (e.g. the vehicle's license plate); determining a current traffic congestion condition for the request to travel, wherein the current traffic congestion condition provides information about the traffic's density or rate of flow along one or more routes for the travel request from the user; determining a travel delay based on the request and based on the current traffic congestion condition, wherein the travel delay represents a waiting time after the request to travel; and transmitting a message to a device (e.g. smartphone or key fob of user), the message indicating when, based on the travel delay, the vehicle is authorized to begin to travel according to the request. In one embodiment, the travel delay is calculated or determined to provide a vehicle density (vehicles along a route of a known, fixed size) that is below or equal to a goal for vehicle density (e.g. a threshold value), where the goal for vehicle density is below a typical traffic density that exists during “rush hour”, or other peak driving times, when traffic control is not implemented. In another embodiment, the travel delay is calculated or determined to provide a vehicle rate of flow (e.g. average speed of vehicles along a portion of or all of a route) that is above or equal to a goal for vehicle rate of flow, where this goal is above a typical vehicle rate of flow that exists during “rush hour”, or other peak driving times, when traffic control is not implemented. The request to travel can include at least one of: (a) destination or origin; (b) a direction of travel; (c) an origin and destination; or (d) one or more routes. In one embodiment, the method also includes: recording violations for traveling on one or more roads without authorization from the traffic management system based on data received from a set of one or more sensors; and determining fines based on the recorded violations. The one or more sensors can be configured to provide information which is used to detect one or more vehicles travelling on the roads without authorization; the sensors can provide or obtain data such as: camera images of one or more license plates (which can be processed with known optical character recognition techniques to derive a license plate number); radio frequency (RF) signals identifying one or more vehicles; or one or more permission codes specifying identifiers of one or more vehicles and route information for the one or more vehicles. In one embodiment, the one or more sensors are coupled to one or more servers that can cause the fines to be enforced against the users who traveled without authorization. This method can be implemented by one or more data processing systems (e.g. a set of servers) that manage the traffic by determining the travel delay for each request from users who seek to travel on routes which have access controlled by the traffic control system. The users can send their requests to the traffic control system from any one of a variety of devices or methods such as: a phone (via voice or text message); a web browser on a computer or smartphone; an app on a smartphone; a dedicated device in a car; a dedicated device in a self-driving car; a key fob that operates like a long range text pager; the users can also receive the message (which authorizes the start of the trip) on any one of the devices, and the user device that makes the travel request can be different than the user device that receives the message (which authorizes the start of the trip).

In one or more embodiments, a traffic control system can also operate with other devices (in addition to the one or more servers that determine the travel delay and in addition to a user device such as a smartphone and app that sends the request to travel). These other devices can include one or more of: sensors for road and traffic conditions; enforcement sensors designed to detect whether vehicles are authorized to be traveling along one or more routes; one or more servers configured to provide privacy and/or to anonymize requests to travel and/or vehicle identifiers (such as license plate numbers or vehicle identification number); and one or more servers operated by or under the control of one or more government agencies that can implement and enforce fines for vehicles which are caught traveling without authorization.

The sensors for road and traffic conditions can be conventional or existing sensors, such as cameras, that provide information about one or more of: traffic density, or traffic rate of flow or road conditions such as accidents, road failures, etc.

The enforcement sensors can be fixed roadside sensors or sensors on vehicles, such as smart license plate holders, that can, in one embodiment, receive permission codes from vehicles along the one or more routes that have access controlled by a traffic control system. For example, in one embodiment, a fixed roadside enforcement sensor can receive a permission code containing the vehicle's license plate number (or an obfuscated version of that number, such as hash of that number) and then compare that license plate number (obtained from the permission code) to the license plate number captured by the enforcement sensor (which can be captured either with a camera or by an RF signal, containing the license plate number, transmitted by a device, such as a toll transponder or smart license plate holder, on the car). If the enforcement sensor determines that the two license plate numbers (or hashes of the numbers) do match, then the enforcement sensor, which is coupled to the traffic control system, does not report a violation, but if the enforcement sensor determines that the two license plate numbers do not match then the enforcement sensor does report a violation to one or more of the traffic control system or government agencies. In one embodiment, the enforcement sensor receives a salt value and the license plate number and the permission code from a device on the vehicle (such as a key fob on the vehicle or a smart license plate holder on the vehicle), and the enforcement sensor (either a fixed roadside sensor or a smart license plate holder on another vehicle) uses the salt, the permission code, and the license plate number to determine whether the license plate number (or salted hash of that number) contained in the permission code matches the license plate number (or obfuscated version of the number) on the vehicle. Other information about such enforcement sensors is described further below.

In one embodiment, a traffic control system can operate in conjunction with one or more data processing systems, such as one or more servers, that provide privacy or anonymize requests to travel and/or vehicle identifiers. These servers can be coupled to both the traffic control systems and also to the user devices that send requests to travel and receive messages authorizing the start of the traveling/trip. These servers can be referred to as permission privacy servers. In one embodiment, a permission privacy server can include a network interface (e.g. Ethernet interface) and a processing system coupled to the network interface and memory coupled to the processing system, and the network interface is configured to communicate with a traffic control system that transmits messages to user devices (such as users' smartphones or key fobs), which messages indicate when vehicles are authorized to begin to travel; the processing system is configured to receive requests to travel from the user devices, where the requests specify the vehicle identifiers (or obfuscated versions of the vehicle identifiers), and the processing system is configured to transmit anonymized identifiers, corresponding to the vehicle identifiers, to the traffic control system to permit the traffic control system to identify vehicles without using the actual vehicle identifiers.

The present disclosure includes the words “optimally” or “optimum” or similar words, and it should be appreciated that the use of such words is not intended to require that the embodiments described herein are in fact actually optimal solutions because less than actually optimal solutions can still provide significant benefits in reduced travel time. Thus, these words, such as “optimum”, should be interpreted as meaning an improved solution by reducing travel time; in other words, the travel time has been at least improved relative to what it would be without the traffic control systems described herein.

The embodiments described herein can include one or more of methods, devices, systems, and non-transitory computer readable medium that store executable program instructions which when executed by a data processing system cause the data processing system to perform the one or more methods described herein.

The above summary does not include an exhaustive list of all embodiments in this disclosure. All systems and methods can be practiced from all suitable combinations of the various aspects and embodiments summarized above, and also those disclosed in the Detailed Description below.

