In-vehicle Guidance Systems

This measure was provided by Politehnica University Timisoara in 2014 under the CH4LLENGE project, financed by the European Commission.

In-vehicle route guidance systems (IVRGs) have seen great development in recent decades. They have become an important tool in alleviating congestion in the urban road transportation network. As a result of the advantages associated with navigation techniques and popularized digital maps, in-vehicle guidance systems are economical, efficient and useful at the same time. In-vehicle route guidance systems are being accepted by more and more users.

Traditional IVRG means that the system primarily select routes based on the shortest distance between a source and a destination, which is very useful in unfamiliar environments or complex networks. In the next generation, the navigation systems became capable of taking into account different criteria of optimization, not just the shortest path. Today, new advanced systems are capable of incorporating real-time congestion delays and rely on other sophisticated methodologies in order to forecast traffic, which allow the users to find the shortest travel time route instead of the standard shortest distance route, enabling users to adapt to dynamic traffic conditions and even to take into account the occurrence of incidents.

In principle, finding the optimal route and avoiding congested areas might lead to an increase in overall capacity of the network and to reduced travel time for most motorists, which could increase supply. IVRGs might have a significant positive effect on efficiency, safety and the natural environment. There are some possible negative effects on safety, because of the higher traffic volumes on secondary roads and the possible distraction caused by the usage of the system and the cognitive process generated by the new, extra information. The overall effect on safety is under debate and is the focus of the research.  IVRGs could boost the local economy as there remains more time that is productive for people living or working there and less stress caused by traffic. Liveability of some secondary roads could be decreased by the higher traffic volumes induced by rerouting from the main roads. Even for most of the non-equipped (non-informed) users IVRGs might produce gain, because they will drive in lower levels of congestion.

Introduction

In-vehicle route guidance (IVRG) systems aim to reduce traffic congestion and its associated environmental, social and financial costs by making drivers more aware of the various options available to them in making a journey and, in the same time, it is possible to increase safety.

Terminology

In-vehicle route guidance systems are often referred to as in-vehicle navigation and route guidance systems or in-vehicle route guidance and information systems.

Description

Navigation is essential to many real-world tasks, such as driving. Geographic disorientation, or getting lost, is associated with a higher risk of crash involvement and economic and ecological waste. Recent technological advances have led to the development of global positioning satellite (GPS) - based in vehicle route guidance systems (IVRGs) that can assist people with the demanding task of navigation. IVRGs are designed to accommodate the individual differences of drivers in their abilities to navigate and in their preferred navigational strategy, will assist the driver with the navigational task, thus reducing attentional demands and distraction potential and ultimately promoting increased transportation safety and efficiency.

First-generation navigation systems, offering static route guidance, primarily select routes based on the shortest distance between a defined origin and destination. More advanced systems are capable of incorporating real-time congestion delays, which allow the users to find the shortest travel time route instead of the standard shortest distance route, and enabling users to adapt to dynamic traffic conditions, through dynamic route guidance. In  in-vehicle  dynamic route  guidance,  in  order  to  provide  the  driver  with  a  fast  and  reliable  route, current and anticipated congestion have to be taken into account.

How does it work?

Static route guidance systems are based on the integration of GPS (Global Positioning System) transponders in a vehicle with electronic maps. In vehicle static navigation systems rely on both latitude and longitude of current car position and match these with a digital map inside the system. After inputting the destination node, the system will calculate a path for users to take and guide them to reach the destination point. There are digital map services on the internet even for smart phones and personal digital assistants (PDAs). As a consequence, people can use the service even when there is no navigation equipment at hand. Today, with the very high market penetration of smart-phones, IVRGs are even more at hand for almost every motorist.

In static route guidance, the possible routes are computed based on the average traffic conditions (e.g, based on historical data or on the type of roads, such as urban corridor, highway, local road, etc.). The static route guidance system is easy to implement and requires little computation time, but it does not work well when an unexpected event happens such as an accident or in a heavily congested network.

If the current traffic conditions such as traffic congestion, incidents, dynamic speed limits, and on-line predictions of travel times using real-time traffic data are taken into account while computing the route recommendations, then we have a dynamic route guidance system. Dynamic route guidance systems can improve the traffic flow, by providing route recommendations to the vehicles such that congestion is prevented from occurring or such that the effects of traffic jams are mitigated.

Dynamic route guidance includes centralized and decentralized systems. Both can provide dynamic routing decisions. The main difference is that the former exchanges information between a vehicle and an information centre, providing more reliable and accurate information at the overall level, while the latter is based on estimated link travel time to make route decisions and is operated within the vehicle unit or could be based on wireless vehicle-to-vehicle communication.

Some of the state-of-the-art route guidance systems make use of Vehicular ad hoc Network (VANET) to collect real-time traffic information to find better paths. There are two types of approaches to collecting real-time traffic information: the infrastructure-based approach and infrastructure-free approach. The infrastructure-based approach employs Vehicle-to-Roadside (v2r) communication to collect real-time traffic information. With this approach, a large number of roadside sensors and communication equipment need to be installed to monitor the traffic condition on each road. The roadside sensors and communication equipment make use of v2r links to collect the required traffic information such as flows, trip times and/or speeds, density and queues length when appropriate. If there are traffic monitoring systems in the area, they could be source for that real-time information. On the other hand, the infrastructure-free approach employs Vehicle-to-Vehicle (v2v) communication. With this approach, there is no need for roadside sensors and communication equipment, because all messages are exchanged between vehicles using v2v links.

Why introduce in-vehicle route guidance?

Navigation is an attention-demanding aspect of the driving task. In-vehicle route guidance systems have the potential to reduce the attention demands of navigating. However, they also have the potential to distract or confuse drivers.

IVRGs guide drivers along their route to any chosen destination, being especially useful in an unfamiliar network. Adding real-time traffic information about current incidents, accidents, road works and special events lets drivers change routes and save time.

Static systems are used for driving in unfamiliar environments, in order to help preventing geographic disorientation, or getting lost, which is associated with a higher risk of crash involvement and extensive economic and ecological waste.

Dynamic route guidance have the potential to reduce the level of congestion or even to prevent the appearance of it and to improve the efficiency of the network by reducing overall travel time, as it is usable even in familiar networks for the daily trips. As a consequence, the level of environmental pollution might be reduced.

Demand impacts

The benefits of the IVRG are difficult to assess and there is little clear evidence on the effect on demand. It can be expected that by using IVRGs the level of stress of the drivers should be reduced significantly. It is probable that by rerouting and avoiding or alleviating congestion, the overall capacity of the network will increase (closer to the optimal capacity), thus, demand might increase.

These impacts on demand are not expected to vary much over time.

Supply impacts

The amount of time saved under recurring congestion is greatest when traffic is near capacity, when small changes in traffic flow can make large differences in travel times. When traffic is much lower than capacity, dynamic route guidance has few opportunities to save time, while for over-saturated conditions, uncongested alternatives may not be available either. The greatest value for dynamic IVRG is with non-recurring congestion caused by incidents that cannot be anticipated.  Furthermore, IVRG reduces the variance in the travel time, making private vehicle transportation more reliable.  The natural consequence is some additional induced demand, the amount proportional to the amount of time saved.

By reducing the uncertainty in direction finding, IVRG may help to reduce inter-vehicle headways and thus induce minor improvements in link capacity.  More significantly, redirecting drivers to more direct routes and away from congested locations may increase network capacity, and offer a more balanced use of that network capacity.  The scale of such effects will depend on the proportion of drivers equipped and using IVRG, and the extent to which increased capacity attracts increased traffic. 

Financing requirements

The infrastructure-based approach of dynamic IVRG employs Vehicle-to-Roadside (v2r) communication to collect real-time traffic information. Obviously, the infrastructure based approach is a costly solution since it needs to install, manage and maintain a large number of roadside sensors, although the existence of a traffic management system could be a source of real-time information without the need for to high extra investments. In comparison, the infrastructure-free approach employs Vehicle-to-Vehicle (v2v) communication, which might have significantly lower costs. It is obvious that even mixed systems could be designed and implemented.

Widespread adoption of in-vehicle navigation systems providing real-time in-route guidance is probably inevitable as the costs of electronics and communications decline while congestion fails to abate.  To achieve this, the quality of the information used by those systems will need to be improved through some combination of public and private resources.  Whether the main source for measuring roadway speeds and detecting incidents is vehicle probes (using cellular phones, toll tag readers, cameras with license plate matching or special purpose devices), or roadway based sensors (magnetic loop detectors, cameras, lasers, or other technologies), or both is still unclear.  But the method of detection will affect the level of public involvement in collection.  Public resources to collect and disseminate real-time traffic data to travellers may help overcome the chicken-and-egg problem of IVRG not being valuable until there are many users and high quality information. However, public involvement may not be needed forever.  Plausibly, the public sector will become an information customer (for use in traffic control and emergency response) rather than producer when the market of advanced traveller information systems matures.  Many new technologies do not require directly access to the public right-of-way in the same way that older technologies such as loop detectors do (Levinson et al. 1999).

Expected impact on key policy objectives

IVRGs have the potential to contribute to almost all key objectives.

Expected impact on problems

Expected winners and losers

Barriers to implementation

The majority of problems which jeopardise the proper functioning of accessible guidance systems, are a result of ignorance and negligence. Among these problems are planning errors (e.g., tactile floor markings leading directly into lampposts or other barriers) and lack of maintenance (e.g., signs hidden by growing plants or tactile floor markings covered with autumn leaves) as well as carelessness in daily life (e.g., vehicles parked on tactile floor markings or information boards masked with stickers and advertising). Therefore it is essential that both the general public and the stakeholders involved in planning, construction and maintenance of roads and buildings, fully understand and accept the importance of accessible guidance systems.

Usually the main argument against the implementation of accessible guidance systems is the cost. Especially the implementation of tactile guidance systems in existing roads and building may be quite costly. Therefore it is essential that accessible guidance systems are included already in the planning stage of all construction and reconstruction works for roads and buildings, since the (additional) costs for accessible guidance systems are minimal when integrated in the construction process.

Although there is considerable research into IVRG, most is concerned with operational issues, rather than assessment against the kinds of objectives considered, and for many measures it is still too early to judge their effectiveness in widespread application. There are very few assessments and they are mainly based on simulations.]

Puget Sound In-Vehicle Traffic Map Demonstration

The purposes of this project were to gain a better understanding of the benefits of providing in-vehicle congestion information and to determine whether any detectable congestion level changes resulted from providing this information (Briglia et al. 2010).  The project tested an in-vehicle traffic map device (TrafficGauge, which shows real-time traffic information for most major U.S. cities) using 2,215 participants from the Puget Sound region (in the city of Bellevue near Seattle, Washington,USA).

Impact on demand

• Pattern: no change in numbers or length of journey or destinations.
• Mode: no reported modal change.
• Timing: the second most common changes were changes to time of departure (18%).
• Route: the most common changes were changes to travel route (66%). Over 46% indicated they benefited from the change, 3% indicated they did not benefit, and 51% did not reply.

Impact on supply

The corridor analysis indicated that even without arterial performance information, some travellers seek alternative routes when the freeway becomes congested.  The corridor analysis confirmed that many travellers diverted either on the basis of what they see on the roadway or what they get from en-route traffic information sources. Even the modest levels of diversion observed in this study increased  congestion on the wider road network, especially near freeway ramps. This visible arterial congestion near the freeway discouraged diversion. Consequently, providing arterial performance information on the entire corridor via in-vehicle devices is likely to increase initial diversion, thereby degrading arterial performance.

Other impacts

Survey data indicated that travellers changed their travel routine once for every 4.2 uses that they made of the Traffic Gauge information.

Over 59 percent of the participants indicated that the information provided by the device reduced their level of stress.

On half of the occasions when participants reported changing routes in the daily surveys, they reported not receiving any benefits. For the entire study, 25 percent of participants reported not benefiting at all from the device. The mean amount of time saved on those instances was a little over 30 minutes.  Thirty-two percent of participants indicated that they did not save any time by using the device.

Contribution to objectives

Contribution to objectives

Contribution to alleviation of problems

Appropriate contexts

Briglia, PM, Fishkin, E., Hallenbeck, ME, Wu, YJ. (2010) An Analysis of the Puget Sound In-Vehicle Traffic Map Demonstration. WSDOT Researh Report WA-RD 737.1

Dong, W. (2011) An overview of in-vehicle route guidance system. Australasian Transport Research Forum 2011 Proceedings

Ding, JW, CF Wang, FH Meng, TY Wu. (2010). Real-time vehicle route guidance using vehicle-to-vehicle communication. IET Commun., 2010, Vol. 4, Iss. 7, pp. 870–883

Levinson, D, Gillen, D, Chang, E. (1999) Assessing the Benefits and Costs of Intelligent Tranportation Systems: The Value of Advanced Traveler Information Systems. California PATH Research Report. UCB-ITS-PRR-99-20

Levinson, D. (2003) The value of advanced traveller information systems for route choice. Transportation Research Part C 11 (2003) 75–87

Elvik, R, Hoeye, A., Vaa, T., Soerensen M. (2009). The Handbook of Road Safety Measures. 2nd edition. Emerald.

Hu, J., Kaparis, I., Bell, MGH. (2009) Spatial econometrics models for congestion prediction with in-vehicle route guidance. IET Intelligent Transport Systems, 3(2), pp. 159-167

Links

AMITRAN project http://amitran.teamnet.ro/index.php/Dynamic_Navigation_System