3.2 Driver Assistance Systems

ITS technologies that assist driving tasks continue to gain interest in the marketplace. Several applications are currently available, while others are in various phases of operational tests:

• In-vehicle navigation and route guidance systems with Global Positioning System (GPS) technology may reduce driver error, increase safety, and save time by improving driver decisions in unfamiliar areas.
• Integrated communication systems that enable drivers and dispatchers to coordinate re-routing decisions on-the-fly can also save time, money, and improve productivity.
• In-vehicle vision enhancement improves visibility for driving conditions involving reduced sight distance due to night driving, inadequate lighting, fog, drifting snow, or other inclement weather conditions.
• Object detection systems, such as parking aids for passenger vehicles, warn the driver of an object (front, side, or back) that is in the path or adjacent to the path of the vehicle.
• Adaptive cruise control, intelligent speed control, and lane-keeping assistance assist drivers with safe vehicle operation.
• Roll stability control systems take corrective action, such as throttle control or braking, when sensors detect that a vehicle is in a potential rollover situation.
• Drowsy driver warning alerts the driver that he or she is fatigued, which may lead to lane departure or road departure.
• Precision docking systems automate precise positioning of vehicles at loading/unloading areas.
• Coupling/decoupling systems help vehicle operators link multiple vehicles, such as buses or trucks, into platoons.

Recently, real-time on-board monitoring applications have been developed to track and report cargo condition, safety and security, and the mechanical condition of vehicles equipped with in-vehicle diagnostics. This information can be presented to the driver immediately, transmitted off-board, or stored. In the event of a crash or near crash, in-vehicle event data recorders can record vehicle performance data and other input from video cameras or radar sensors to improve the post-accident processing of data.

Figure 3.2.1 summarizes the classification of benefits and costs data for driver assistance systems.

Many of the driver assistance systems discussed above have begun to emerge in mainstream markets. While system performance and safety testing has been performed by vehicle manufacturers, the impacts of deployment of these technologies on the operation of the transportation system will continue to be evaluated as deployment becomes more widespread. Cost data are not readily available for systems that remain in development stages or even for those systems in the commercial market. Furthermore, many reports and studies on driver assistance systems contain little or no cost data, or are based on estimates and/or market analysis of the public's willingness to pay for a specific in-vehicle feature. Also, some of these features are available as factory-installed options, as standard items included in the base cost of a vehicle, or as a component of an upgrade package. Hence, this section contains few examples of system cost data.

Table 3.2.1 provides information on the benefits and costs of driver assistance systems. An assessment of the impact of these systems is indicated by using the symbols in the Impact Legend at the bottom of each page.

Table 3.2.1 – Benefits and Costs of Driver Assistance Systems

Navigation/Route Guidance

Benefits
Goal Area	# of Studies	Impact	Example
Safety	2	?	Safety impacts of in-vehicle navigation systems were estimated using simulation models and field data collected from the TravTek project. Results indicated users could decrease their crash risk by up to 4%.[164]
Mobility	4	+	The City Laboratories Enabling Organization of Particularly Advanced Telematics Research and Assessments (CLEOPATRA) project in Turin, Italy, demonstrated a time savings of more than 10% for cars equipped with in-vehicle navigation devices.[12]
Capacity/ Throughput	2	?	Capacity improvements from in-vehicle navigation systems were estimated using simulation models and field data from the TravTek project. Using a market penetration rate of 30%, and overall average trip duration as a surrogate for a given level of service, dynamic route guidance enabled the system to handle a 10% increase in demand.[164]
Customer Satisfaction	3	+	In-vehicle navigation units were distributed to public agencies in the San Antonio, Texas, area as part of the San Antonio Metropolitan Model Deployment Initiative (MMDI). Focus groups composing drivers of vehicles equipped with the units indicated that the drivers most satisfied with the system were those who frequently drove different routes each day, particularly paratransit drivers and police investigators.[10]
Costs
Unit Costs Database	Vehicle On-Board subsystem		See Appendix A
System Cost	In-vehicle navigation units were distributed to public agencies in the San Antonio, Texas, area as part of the San Antonio MMDI. The units provided route guidance and real-time traffic conditions. The cost of the units (590 at approximately $2,800 each) was the most significant cost driver for the project. Most of the operations and maintenance (O&M) cost is attributed to database updates.[10]		Total project cost: $2,388,691 (1998) Annual O&M cost: $102,330 (1998)

Driver Communication with Carrier/Dispatch

Benefits
Goal Area	# of Studies	Impact	Example
Productivity	2	+	An advanced routing and decision-making software communications program for commercial vehicles helped dispatchers organize and route time-sensitive delivery orders. The system increased the number of deliveries per driver-hour by 24%.[165]
Costs
Unit Costs Database	Emergency Vehicle On-Board subsystem Transit Vehicle On-Board subsystem Commercial Vehicle On-Board subsystem Vehicle On-Board subsystem		See Appendix A
System Cost	The automated vehicle location (AVL) system installed by the Regional Transit District (RTD) in Denver, Colorado, included the capability for voice and data communication between fleet vehicles and the dispatch center. The GPS/in-vehicle logic unit/transit control head was approximately $3,517 per bus.[92]		AVL system cost: $10.4 million

Adaptive Cruise Control

Benefits
Goal Area	# of Studies	Impact	Example
Safety	1	+/-	Ten vehicles were equipped with adaptive cruise control, including automatic throttle modulation and down shifting (but not braking) to maintain preset headways during a NHTSA field test. The performance of the system was compared to conventional cruise control and manually operated vehicles. Results indicated that vehicles equipped with adaptive cruise control made the fewest number of risky lane changes in response to slower traffic. Manually operated vehicles, however, had the quickest average response time to lead vehicle brake lights.[26]
Capacity/ Throughput	3	+	In the Netherlands, a simulation model investigated the impact of an automated braking system capable of automatically resetting itself after activation in the operational speed range of 30 to 150 km/hr. With a market penetration of 20%, and a headway setting of 0.8 seconds, the system increased capacity by 3.2%. However, if headway was set at 1.2 seconds, capacity increased by only 1.0%.[166]
Customer Satisfaction	2	+	The adaptive cruise control system deployed in the NHTSA field test generally had a very high level of acceptance by the participants. Participants overwhelmingly ranked adaptive cruise control over the manual and conventional cruise control-equipped vehicles for convenience, comfort, and enjoyment. Participants indicated they would most likely use the system on freeways.[26]
Energy/ Environment	3	+	Driver response and vehicle dynamics were recorded for one adaptive cruise control vehicle and two manually operated vehicles in a single lane of freeway traffic. The adaptive cruise control vehicle attempted to smooth traffic flow by minimizing the variance between acceleration and deceleration extremes. Simulation models based on collected field data estimated a fuel savings of 3.6% during scenarios with frequent acceleration and deceleration.[167]
Costs
Unit Costs Database	Vehicle On-Board subsystem		See Appendix A
System Cost	A Florida-based trucking company has installed a collision warning system to reduce the number of rear-end incidents. The company installed the collision warning system on 1,682 tractors with plans to outfit the entire fleet of about 4,000. Adaptive cruise control, at an additional cost of $350–$400, can be added to further reduce rear-end collisions.[162, 163]		Average cost for a collision warning system with forward-looking and side sensor: $2,500

Intelligent Speed Control

Benefits
Goal Area	# of Studies	Impact	Example
Customer Satisfaction	1	?	In the southern Swedish town of Eslov, 25 personal vehicles were equipped with governors activated by wireless beacons at city points-of-entry to limit inner city vehicle speeds to 50 km/hr. The vast majority of participants preferred this adaptive speed control over other physical countermeasures such as speed humps, chicanes, or mini-roundabouts.[168]
Costs
Unit Costs Database	Vehicle On-Board subsystem		See Appendix A
System Cost	No data to report.

Coupling/Decoupling

Benefits
Goal Area	# of Studies	Impact	Example
Energy/Environment	1	?	An electronic towbar system coupled two heavy-duty trucks without the aid of a mechanical towbar. The system enabled a trailing truck to autonomously follow a lead truck by a distance of approximately 10 meters. Track testing showed the lead truck and the trailing truck reduced fuel consumption by about 7% and 15–21%, respectively, when traveling at 80 km/hr.[169]
Costs
Unit Costs Database	Vehicle On-Board subsystem		See Appendix A
System Cost	No data to report.

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