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Crash Prevention & Safety > Road Geometry Warning, Crash Prevention & Safety > Road Geometry Warning


Road geometry warning systems warn drivers, typically those in commercial trucks and other heavy vehicles, of potentially dangerous conditions that may cause rollovers or other crashes on ramps, curves, or downgrades. , Rollover warning systems notify drivers when they are traveling too fast for an approaching curve, given their vehicles operating characteristics. This has been primarily a focus of heavy trucks.


Obtain working prototypes of CV applications from the USDOT’s Open Source Application Data Portal (OSADP) to prevent time spent doing duplicative software development(11/01/2017)

Include technical, operations, and legal personnel in stakeholder meetings to address the requirements of the CV deployment and ensure that participants' privacy is being maintained(11/01/2017)

Separately deploying mileage-based user fee and in-vehicle safety alert functions helps ensure each technology has the best opportunity for user acceptance.(02/01/2013)

Use speed warning signs on dangerous curves to reduce speeds of trucks.(November 2001)

Use speed warning signs on dangerous curves to reduce speeds of trucks.(November 2001)

During system testing, CV Pilot sites discover the importance of having expertise in detecting and mitigating interferences with radio frequency and GPS signals(12/13/2018)

Refine institutional arrangements when deploying connected vehicle technology to outline the expectations of partners in terms of service, outcomes and reporting.(12/13/2018)

Refine proper antenna placement on connected vehicles (particularly commercial vehicles) to reduce DSRC ‘shadow’ areas where DSRC signal is degraded.(12/13/2018)

Connected vehicle deployers are encouraged to utilize multi-vendor outsourcing and to source suppliers early to create a collaborative environment that enables as much parallel work as possible.(12/13/2018)

Connected vehicle deployers should assess field equipment and organizational capabilities that will be needed to support core CV components.(12/13/2018)

Use local student mechanics where possible to perform CV equipment installations to provide students with required trainee experience and to contain costs(11/01/2017)

Allow for increased coordination with the Interdepartmental Radio Advisory Committee (IRAC) early on in the DSRC licensing process to help reduce what is traditionally a very lengthy process.(11/01/2017)

Incorporate standardized over-the-air update procedures to permit efficient firmware updates for connected vehicle devices.(11/01/2017)

Use on-board connected vehicle (CV) technology and SPaT / MAP infrastructure messages to prevent wrong way entries on reversible express lanes.(11/01/2017)

Publish all CV planning documentation to serve as an example for other early deployers to follow(11/01/2017)

Specify interoperability testing requirements and steps as part of the connected vehicle device requirements prior to starting multiple rounds of testing, feedback, reset, and retesting.(September 2015)

Use a modular project structure and focus on high priority objectives and project components when deploying complex ITS projects such as those with connected vehicle technologies. (September 2015)

Clearly communicate requirements and testing procedures to connected vehicle device developers, and allow for industry input and iteration for less mature devices. (September 2015)

Conduct a data collection pilot test to validate end-to-end data acquisition, transfer, processing, and quality assessment processes.(September 2015)

Recognize staffing and communication needs for Advanced Traveler Information Systems (ATIS) projects.(April 2006)

Recognize integration issues in Advanced Traveler Information Systems (ATIS) Projects, and follow the systems engineering approach to establish a project's foundation.(April 2006)

Assess needs and communication infrastructure capabilities for the design of an Advanced Traveler Information System (ATIS).(April 2006)

Passive safety treatments were found to be more reliable and affordable than active safety treatments on two-lane rural roads with dangerous horizontal curves in Virginia.(June 2018)

Sequential Dynamic Curve Warning System reduces the number of vehicles exceeding the speed limit by 10 mph or more by 27.8 percent(January, 2014)

Approximately 75 percent of drivers in a large-scale field operational test felt that curve speed warning systems increased safety.(11/21/2012)

A Benefit Cost analysis shows that dynamic curve speed warning signs have 30 percent effectiveness and an incremental B/C ratio between 2.79 to 5.57 for curves that already have static curve warnings.(December 2009)

Simulated Rural Highway Driver Warning Systems (RHDWS) showed a potential reduction of critical events by 21 percent, a decrease of 71 percent for runoff-road crashes, and contributed to smoother driving on the curvy highway.(May 2009)

In Myrtle Creek, Oregon, an advanced curve speed warning system installed on I-5 reduced the speed of 76 percent of drivers surveyed.(June 2006)

In Colorado, a downhill truck speed warning system installed on a curved section of I-70 reduced 85th percentile truck speeds by 27 percent.(November 2001)

An advanced curve warning system on an interstate route in northern California caused over 68 percent of drivers to reduce their speed. (April 2000)

More than 76 percent of drivers on an interstate route in northern California indicated that messages displayed by an advanced curve warning system were useful.(April 2000)

In Oregon and Colorado, downhill speed warning systems decreased truck crashes up to 13 percent at problem sites.(31 October 2006)

In Colorado, a downhill truck speed warning system installed on a curved section of I-70 reduced 85th percentile truck speeds by 27 percent.(November 2001)

A dynamic truck down hill speed warning system installed on I-70 in Colorado reduced the average speed of passing trucks by approximately 5.2 mi/hr. (15 December 1999)

A small-scale study of truck drivers who experienced a dynamic truck down hill speed warning system in Colorado indicated that most drivers thought it was helpful.(15 December 1999)

In Colorado, a dynamic truck downhill speed warning system (DSWS) installed on I-70 decreased the number of accidents by 13 percent.(15 December 1997)

In Colorado, a down hill truck speed warning system installed on I-70 reduced runaway ramp usage by 24 percent and contributed to a 13 percent drop in crashes involving trucks and excessive speeds.(May 1997)

Overheight vehicle detection systems on I-10 in Houston reduced bridge hits by 66 percent.( July/August 2018 )

Overheight vehicle detection systems on I-10 in Houston contributed to 20 fewer bridge hits per year, saving TxDOT more than $2 million in annual bridge repair costs.( July/August 2018 )

The cost to purchase and install an overheight vehicle detection system (OHVDS) was estimated at $100,000 per location.( July/August 2018 )

Most professional truck drivers interviewed in Ohio and California expressed favorable views of on-board connected vehicle safety applications installed on Class 8 commercial vehicles.(01/31/2014)

At a tunnel in Pennsylvania, an overheight/overwidth warning system improved safety; occasional crashes demonstrate value of system and importance of maintenance.(31 October 2006)

A nationwide survey evaluating overheight/oversize warning systems found that eight states that deployed active infrared light or laser activated warning systems had fewer overheight load strikes on infrastructure components.(12-16 January 2003)

At the Breezewood Interchange on the Pennsylvania Turnpike, installation of a truck rollover warning system immediately reduced the occurrence of truck rollover crashes.(April 2006)

Evaluation Results of Three Prototype Automatic Truck Rollover Warning Systems(11-15 January 1998)

After a ramp rollover warning system was installed at three curved exit ramps on the beltway around Washington, DC, there were no accidents at any of these sites during the three year post deployment test period evaluated.(15 December 1997)

In Colorado, a down hill truck speed warning system installed on I-70 reduced runaway ramp usage by 24 percent and contributed to a 13 percent drop in crashes involving trucks and excessive speeds.(May 1997)

Rapid deployment of DSRC for connected vehicles can save thousands of lives, regardless of whether a later transition to C-V2X proves advantageous.(12/12/2017)

Dynamic Speed Feedback Signs on Curves cuts number of single-vehicle crashes nearly in half.(January 2015)

Simulated Rural Highway Driver Warning Systems (RHDWS) showed a potential reduction of critical events by 21 percent, a decrease of 71 percent for runoff-road crashes, and contributed to smoother driving on the curvy highway.(May 2009)

Through use of the Roll Stability Control (RSC) systems, it was estimated that between 1,422 and 2,037 combination vehicle rollover crashes in curves could be prevented, resulting in effectiveness rates of 37 percent and 53 percent, respectively.(February 2009)

An analysis of benefits and costs of Roll Stability Control (RSC) Systems for the trucking industry found benefits per dollar spent values of $1.66 to $5.34 with varying estimates of efficiency and annual VMT.(February 2009)

Forward collision warning systems have potential to prevent 23.8 percent of crashes involving large trucks.(2009)

An evaluation of electronic stability control (ESC) and crash data from the Institute for Traffic Accident Research and Data Analysis indicated that the crash rate for single-car crashes and head-on crashes decreased by about 36 percent where ESC was expected to be effective.(18 February 2005)

In-vehicle rollover advisory control warning messages are expected to prevent 20 percent of rollover crashes caused by excessive speed in curves, based on driving data collected during a Freightliner FOT.(September 2003)

A Dynamic Curve Speed Warning Sign (with a Flashing Beacon and Radar Detection) system ranges from $9,000 to $14,000(December 2009)

In Colorado, a Truck Tip-Over Warning System was deployed on I-70 at a cost of $446,687.(31 October 2006)

Colorado DOT deployed a truck speed warning system in Glenwood Canyon at a cost ranging from $25,000 to $30,000.(November 2001)

Colorado DOT deployed a truck speed warning system in Glenwood Canyon at a cost ranging from $25,000 to $30,000.(November 2001)

An overheight warning system in Maryland cost a total of $146,000(04/02/2011)

Based on a nationwide survey of states operating overheight detection systems, the initial costs of active laser- or infrared-based systems vary considerably, ranging from $7,000 to $70,000.(12-16 January 2003)

The Michigan Department of Transportation estimated that an ITS-based active overheight detection and warning system installed at both approaches to a bridge would cost $110,000.(24-27 March 2002)

The Pennsylvania (PA) Turnpike Commission expanded its statewide advanced traveler information system (ATIS) to better inform motorists of traffic, weather, and emergency conditions along the PA Turnpike. The overall project cost was $8.2 million.(April 2006)

The cost of an automated truck rollover warning system can vary significantly, ranging from $50,000 to $500,000.(7 December 2005)

The cost of a prototype truck rollover warning system on the Capital Beltway in Virginia and Maryland was estimated at $166,462 for a one-lane ramp and $268,507 for a two-lane ramp.(11-15 January 1998)

The cost for Roll Stability Control (RSC) systems for large trucks range from $439.99 and $1,101.39.(February 2009)

Dynamic Curve Speed Warning Sign (High) - Capital cost/unit - $14000 - Lifetime - 20 years(December 2009)

Dynamic Curve Speed Warning Sign (Low) - Capital cost/unit - $14000 - Lifetime - 20 years(December 2009)

Truck Tip Over Warning System - Capital cost/unit - $278611(31 October 2006)

Blank Out Sign (Fiber Optic) (4 Ea.x 8,788 $/ea.) - Capital cost/unit - $10457.5(31 October 2006)

Steel Sign Post (W 6x12) (39.5 lf x 23 $/lf) - Capital cost/unit - $23(31 October 2006)

Concrete Footing (Type 1) (2 ea x 941 $/ea) - Capital cost/unit - $941(31 October 2006)

Steel Sign Post (W 8x18) (33 lf x 32 $/lf) - Capital cost/unit - $32(31 October 2006)

Concrete Footing (Type 3) (3 ea x 976 $/ea) - Capital cost/unit - $976(31 October 2006)

Truck Curve Warning and High Wind Warning System for Bridge - Capital cost/unit - $572000 - Lifetime - 20 years(3/18/2006)

Truck Speed Warning System - Capital cost/unit - $35000 - O&M cost/unit - $500 - Lifetime - 7 years(8/28/2003)

Roadside message sign - Capital cost/unit - $35(01/19/2018)

Overheight vehicle detector system controller - Capital cost/unit - $35(01/19/2018)

Overheight vehicle detector - Capital cost/unit - $35(01/19/2018)

Cellular modem - Capital cost/unit - $35(01/19/2018)

Electrical conduit - Capital cost/unit - $35(01/19/2018)

Warning siren - Capital cost/unit - $35(01/19/2018)

Electrical pull box - Capital cost/unit - $35(01/19/2018)

Electrical conduit - Capital cost/unit - $35(01/19/2018)

Communications cabinet - Capital cost/unit - $35(01/19/2018)

Roadside flasher beacon - Capital cost/unit - $35(01/19/2018)

Electrical conduit - Capital cost/unit - $35(01/19/2018)

Loop Detector - Capital cost/unit - $9(01/01/2012)

Loopd Detector Lead - Capital cost/unit - $9(01/01/2012)

Overheight Detection System - Capital cost/unit - $9(01/01/2012)

Loop Detector - Capital cost/unit - $9(01/01/2012)

Loopd Detector Lead - Capital cost/unit - $9(01/01/2012)

Overheight Detection System - Capital cost/unit - $9(01/01/2012)

Overheight Detection System - Capital cost/unit - $150000 - O&M cost/unit - $500 - Lifetime - 15 years(6/19/2006)

Machine Vision Sensor on Corridor - Capital cost/unit - $3000 - O&M cost/unit - $10000 - Lifetime - 7 years(3/17/2007)

Systems Integration - Capital cost/unit - $25000 - O&M cost/unit - $4000 - Lifetime - 5 years(3/17/2007)

Roadside Probe Beacon - Capital cost/unit - $4000 - O&M cost/unit - $6000 - Lifetime - 7 years(3/17/2007)

Twisted Pair Installation - Capital cost/unit - $11000 - O&M cost/unit - $2000 - Lifetime - 10 years(3/17/2007)

Conduit Design and Installation - Corridor - Capital cost/unit - $32000 - O&M cost/unit - $4000 - Lifetime - 10 years(3/17/2007)

Roll stability control for trucks - Capital cost/unit - $2000(April 2011)