Driving_Sim_SOW_010213.docx

STATEMENT OF WORK

Driving Simulator for Highway-Rail Grade Crossing Research

1 Purpose The Volpe National Transportation Systems Center (Volpe Center) of the U.S. Department of Transportation supports the Federal Railroad Administration (FRA) in their mission to reduce and prevent accidents at highway-rail grade crossings. The Volpe Center requires a driving simulator to evaluate human factor issues and countermeasures directed to promote drivers’ safety at highway-rail grade crossings.

This document sets forth the requirements for the driving simulator system for the design and presentation of virtual scenarios for the evaluation of driving behavior and performance at highway-rail grade intersections.

2 Background Volpe Center’s Human Factors Research Division will focus on driving behavior at highway-rail grade crossings. Driver behavior at highway-rail grade crossings depends on several factors including: 1) seeing and comprehending warning devices, 2) detecting the presence of a highway-rail crossing, 3) detecting the presence of a train, 4) judging time-to-collision, and 5) deciding what to do. There are several benefits associated with the use of driving simulators for highway-rail grade crossing research. One benefit is the ability to create traffic events (e.g., train approach , signal activation) based on the position or speed of the motorist, which allows for examination of critical events where limited time is available to the motorist for detecting cues, making decisions, and responding. Another benefit of using a simulator is the type and amount of driving performance data that can be collected, when compared to other data collection methods, such as on-road video imaging analysis. The driving simulator system shall provide the Government with the ability to create and modify experimental scenarios in a simple, relatively easy way without requiring expertise in programming code writing, thus, reducing the development time.

3 Hardware Requirements and Physical Configuration The driving simulator system shall be configured to fit in the floor space shown in the following diagram. The overall dimensions of the room are 18 feet by 19 feet with a 10-foot ceiling height. Because of the structural column near the center of the room and the other simulator, the floor space occupied by the driving simulator can be no more than 10.5 feet wide if the depth is greater than 7.5 feet, or no more than 13 feet wide if the depth is less than 7.5 feet.

The opening through the double doors measures 90 inches by 80 inches.

Full vehicle or half-cab simulators are not within the scope of this Statement of Work. The physical configuration shall include:

3.1 A unit that combines the visual display(s), an adjustable driver seat, steering wheel, instrument panel, accelerator and brake pedals.

3.2 The visual display shall provide a 180 degree field of view and at least 25” high, adequate to examine driver eye and head movements as the driver approaches an intersection (i.e., highway-railroad grade crossing). Third party visual systems (ex, cylindrical, domed or blended projector) will be considered if value and effective integration with the simulator can be demonstrated. Distortion of a visual object (ex. Vehicles, signs, marking, etc.) near the visual limit of the display (70 – 90 degrees from center) not to exceed 15%.

3.3 Greater than 30 frames per second graphical display update rate when 10 or greater vehicle objects and locomotive are in view.

3.4 Computer processing power adequate to meet the above requirements.

3.5 A full-size steering wheel with active force feedback.

3.6 Active force pedals for accelerator and brake.

3.7 Diagrams and description of the physical configuration, computer connections, and wiring diagrams.

4 Software Requirements

A. Features The system shall allow the user to create, assemble, and modify scenarios and scenery elements with minimal programming knowledge or area of expertise. The term scenario is used to describe the combination of the visual scene and dynamics of interest. The visual scene refers to the static elements in the environment such as roads and rail tracks, terrain, roadside elements (e.g., traffic signs, buildings). Dynamics refers to the coordination and interactions between different entities in the simulation including the driver, train(s), and warning systems, such as automatic gates, auditory alerts, and flashing lights. Thus the software shall fulfill these requirements for scenario authoring with the tools available to the experimenter to create, define, and arrange the static and dynamic elements in the simulation.

The software shall include a library consisting of roadside and railroad scenes and elements for scenario authoring by the user. The following items must be included:

4.1 Scenes that include all basic highway-rail intersection geometries found in Appendix A (Figures A-2 to A-7).

4.2 Regulatory, warning and guide signs found in the U.S. Department of Transportation (2009) Federal Highway Administration Manual of Uniform Traffic Control Devices (MUTCD) and all grade crossing signs found in Appendix B (Table B-1 and Figure B-2).

4.3 Post-mounted and overhead-structure traffic signals and all flashing light signals for highway-rail grade crossing found in Appendix B (Figure B-2).

4.4 At minimum, all grade crossing gates found in Appendix B (Figure B-2)

4.5 Gate arms shall display alternative red/white retro-reflectorized vertical pattern

4.6 Gate arms shall include three red lights

4.7 Gate arms should include functionality to display:

4.7.1 Flashing lights + 2 quadrant gates

4.7.2 Flashing lights + 4 quadrant gates (where gate arms extend individually across the entrance and exit lanes of highway traffic, on both sides of the grade crossing).

4.8 Scenes of road that include local roads, highways, and intersections in rural, urban, residential, industrial and commercial areas including typical structures (e.g., buildings, facilities, and signage typical of residential, industrial, and commercial areas).

4.9 A minimum of 5 different structures for each of the following types of scenes: rural, urban, residential, industrial, and commercial.

4.10 Pavement markings for roads, highways, intersections, and highway-rail grade crossings, as applicable. These include, at a minimum, the following markings:

4.10.1 Solid longitudinal line (white)

4.10.2 Broken longitudinal line (white)

4.10.3 One direction no-passing zone marking (yellow)

4.10.4 Two-direction no-passing zone marking (yellow)

4.10.5 Stop lines (white)

4.10.6 Crosswalk

4.11 Pavement markings to be placed, as needed, in advance of a highway-rail grade crossing, including an X, the letters RR, a no-passing marking, and transverse lines (see Appendix B, Figure B-3)

4.12 A minimum of 2 locomotive types, 2 freight rail car types, and 2 passenger rail car types.

4.13 A minimum of 5 different pedestrian types.

4.14 A minimum of 2 animal types

The software must also meet all requirements found in Section 4, Part B, Experimental Capabilities (below).

B. Experimental Capabilities See Reference Material in Appendix A and B.

4.15 Scenery

4.15.1 Allow for the configuration of scenes that depict rural and urban areas including structures typical for residential, industrial, and commercial in both rural and urban areas.

4.15.2 Functionality to simulate daytime and nighttime lighting conditions, time of day, and reduced visibility conditions (e.g., fog, rain, snow) of selectable intensity.

4.15.3 Functionality to add simulated reflection for signs and pavement markings.

4.16 Vehicle Lights

4.16.1 Functionality to display and control (turn on or off) turn signals and headlights for subject vehicle. Headlights should illuminate scenery per typical headlight specifications.

4.16.2 Functionality to display headlights that illuminate scenery for other moving vehicles in the virtual environment.

4.17 Own Vehicle Dynamics

4.17.1 Functionality to select type of vehicle (ex. Car, truck, large truck) and/or set acceleration, braking, and turning rates.

4.18 Roads

4.18.1 Functionality to display, choose from, and arrange a variety of road types such as intersections, local roads and highways

4.18.1.1 Provide 3-leg and 4-leg intersections with a variety number of lanes.

4.18.1.2 Provide transitions for roadway sections with varying number of lanes to be placed between intersections.

4.19 Railroad Tracks

4.19.1 Functionality to display, choose from, and arrange a variety of track types to configure a variety of highway-rail grade crossings (see examples in Appendix A; Figures A-2 to A-7).

4.19.1.1 Railroad tracks are perpendicular to the roadway.

4.19.1.2 Single and multiple railroad tracks at the same crossing.

4.19.1.3 Railroad tracks at intersections with and without median (traffic island).

4.19.1.4 Tracks near straight and curved sections of roadway.

4.19.2 Functionality to display railroad tracks in rural and urban areas.

4.19.3 Crossing surface (where the road and the railroad tracks intersect) must be at the same level as the roadway +/- 2 ft. from the centerline road (see Appendix A, Figure A-1 for reference).

4.19.4 Functionality to add vehicles, stationary and in motion, to the railroad tracks.

4.20 Traffic Signs and Signals

4.20.1 Functionality to display, choose from, and arrange traffic signs which include regulatory, warning, and guide signs. This includes signs required at highway-rail grade crossing as documented in the MUTCD (see Appendix B, Table B-1).

4.20.2 Sign dimensions should adhere to standards for visibility distance (i.e., signs may be oversized relative to standard size to ensure legibility).

4.20.3 Functionality to display post-mounted and overhead-structure traffic signals for a variety of lane numbers and lane group configurations.

4.20.4 Functionality to display signs with continuous or blinking (LED) lights.

4.20.5 Ability to specify the position of signs and signals relative to the highway-rail grade crossing.

4.20.6 Provide tools and documentation to create and import new signs/objects, including traffic signs.

4.21 Flashing Light Signal for Highway-Rail Crossings

4.21.1 Provide flashing light signals (two light units mounted in a horizontal line) and functionality to modify its placement relative to grade crossing (Appendix B Figure B-2).

4.21.1.1 Flashing-light signal shall display toward approaching highway traffic and consist of two red lights mounted in a horizontal line flashing alternately.

4.21.1.2 Flashing-light signal is to be placed on the approach side of the highway-rail grade crossing on the right-hand side. User must have the option for placement on both sides (right and left) of the roadway.

4.21.1.3 Provide post-mounted and overhead flashing light signal structures.

4.21.1.4 Flashing-light signal assembly on the side of the highway shall include a standard Crossbuck sign (see Table B-1 in Appendix B for signs).

4.21.1.5 Provide functionality to display a supplemental “Number of Tracks” sign to the Crossbuck sign in the flashing-light signal assembly to be used with the a standard Crossbuck sign at crossing with two or more tracks (see Table B-1 in Appendix B for signs).

4.21.2 Functionality to control onset of flashing-light signal activation contingent on subject driver’s (and other vehicles’) actions and optionally by the experimenter.

4.21.3 Functionality to vary the flashing rate of the lights. At minimum they must be able to vary from 35 to 65 flashes per minute.

4.21.4 Provide functionality to specify color of the light units on the flashing-light signal. Minimum of two colors: red and amber.

4.22 Pavement Markings

4.22.1 Functionality to display typical pavement markings in advance of a highway-rail grade crossing (as shown in Appendix B, Figure B-3 and described below) and functionality to turn these ‘on’ or ‘off’ as applicable.

4.22.1.1 Typical pavement markings in advance of a highway-rail grade crossing consist of an X, the letters RR, a no-passing marking, and transverse lines

4.22.1.2 The user shall have the option to place these markings in each approach lane close to highway-rail grade crossings where signals or automatic gates are located, at other highway-rail grade crossings where the posted highway speed is 60 km/h (40 mph) or greater, or to not include these markings at all.

4.22.2 Functionality to modify pavement markings by the user/operator.

4.22.3 Functionality to create new pavement marking by the user/operator.

4.22.4 Functionality to modify the position of typical pavement markings for highway-railroad grade crossings (described above) relative to the crossing.

4.23 Automatic Gates

4.23.1 Functionality to specify the color of the lights for automatic gates (Figure B-2), at a minimum two colors shall be provided, red and amber. The default color is red.

4.23.2 Functionality to specify the length of the gate (in ft.).

4.23.3 Functionality to control the operation of automatic gates including the location, movement, activation time and timing of its movement (i.e., upright-downward motion). The list below include guidelines on standard gate operation:

4.23.3.1 In its normal upright position (when no train is approaching or present) the gate arm should be vertical or nearly so.

4.23.3.2 When in the down position, the gate arm shall extend across the approaching lanes of highway traffic.

4.23.3.3 When active, the gate arm light nearest the tip shall be illuminated continuously and the other lights shall flash alternately in unison with the flashing–light signal.

4.23.3.4 The gate arm shall start its downward motion not less than 3 seconds after the flashing-light signal starts to operate, shall reach its horizontal position at least 5 seconds before the arrival of the train and shall remain in the down position as long as the train occupies the highway-rail grade crossing.

4.23.4 Functionality to specify when a train clears the highway-rail grade crossing, and if no other train is approaching, the gate arm shall ascend to its upright position, following which the flashing lights and the lights on the gate arm shall cease operation.

4.23.5 Provide ability to modify placement of automatic gates relative to crossing (distance away from roadside/intersection).

4.23.6 Provide functionality to control the motion of the gate arms (time --in seconds-- to descend to horizontal position/ascend to vertical position).

4.23.7 Functionality to control onset of gate activation contingent on subject driver’s (and other vehicles’) actions and optionally by the experimenter.

4.24 Trains vehicles, other objects

4.24.1 Ability to display locomotives, freight and passenger trains cars.

4.24.2 Freight cars and locomotive should include simulated retro-reflective patterns or provide ability to include simulated reflective signage/markings for placement on trains. The amount and placement of retro-reflective sheeting required is dependent on the size of the car or locomotive, as well as the car type.

4.24.3 Ability to control and modify the properties of the trains including initial position, trajectory, and velocity.

4.24.4 Ability to display headlights (on/off) for all trains.

4.24.5 Functionality to control onset of train events contingent to subject drivers’ (and other vehicles’) actions (e.g., location, speed, time-to-crossing) with train arrival at the crossing approximately 15 seconds after the actuation of flashing lights or gates.

4.24.6 Functionality to display moving vehicles to represent vehicular traffic traveling in the same direction as the subject driver; oncoming traffic; and crossing traffic at intersections.

4.24.7 Functionality to control and modify the properties of vehicular traffic including initial position, trajectory, and velocity (independent and contingent on participant vehicle actions). This includes functionality to specify when and where traffic (including trains) is added to the scene.

4.24.8 Functionality to control and modify the properties of pedestrians and animals including initial position, trajectory, and speed (independent and contingent on participant vehicle actions).

4.24.9 Ability to control train manually by the experimenter or other driver in real-time.

4.24.10 Ability to control > 3 driving vehicles by the experimenter or other driver in real-time.

4.25 User-System Interface

4.25.1 Provide navigation and visualization tools for scene definition, scenario definition, and scenario review.

4.25.2 Provide tools to save and reuse scenarios

4.25.3 Provide tools to randomize the order in which scenarios (i.e., events) are presented to the driver.

4.25.4 Provide functionality to create conditional activated events based on the behavior of the driver (subject vehicle).

4.26 Audio Capabilities and Control

4.26.1 Provide audio speakers to reproduce sounds approaching from the left and right relative to driver seating position.

4.26.2 Provide auditory cues (sounds) that reproduce typical engine sounds associated with changes in vehicle speed /acceleration, sounds of vehicles passing by, etc.

4.26.3 Provide audio recordings/files to reproduce typical sounds found in grade-crossing and roadway environments. At minimum these should include (1) locomotive horn, (2) locomotive bell, (3) grade-crossing bells, (4) car horn and (5) truck horn. Locomotive sounds should include realistic sounding Doppler shift as simulated train approaches the grade crossing.

4.26.4 Provide functionality to control the volume of sound files presented.

4.26.5 Provide functionality to upload new audio recordings/files to the audio library and to insert them into the simulation as needed.

4.26.6 Provide functionality to simulate interior noise of motor vehicles. Fan noise shall be constant at levels controllable by experimenter. Engine noise shall vary with vehicle speed as well as level chosen by experimenter.

4.26.7 Include information about how to upload, playback and control sounds onset and volume as part of simulator documentation.

4.26.8 Provide the capability and functionality to control the onset of audio files contingent to the action of the subject vehicle (and other dynamic elements). It should be possible to have the sound trigger be based on time, location within the simulation, or in response to participant behavior.

4.26.9 Possible to play, at a minimum, two sounds simultaneously such as train horn and grade-crossing bells.

4.27 Data Acquisition and Output Files

4.27.1 Functionality to collect data elements in the simulation with a resolution of at least 30 Hz with ability to specify a resolution of 60 Hz including time-stamps.

4.27.2 Provide output in real-time and saved in a file(s) that can be exported via Ethernet, CANbus or USB ports and used in commercially available statistical software for later examination.

4.27.3 Provide real-time driver position and state output. Provide real-time train position and state output.

4.27.4 Functionality to create video recording of driver simulation session for visual analysis and demonstrations. Video recording are to by in-sync with simulator time to within 200ms.

4.27.5 Functionality to record driver response (e.g. to a visual or auditory stimuli) by providing two response buttons at or near the steering wheel for driver response inputs.

4.27.6 Provide capability for us to use the simulator with an eye-tracker system to collect eye movement data during a simulation session. Ability to sync time of the simulator with an external eye tracking PC computer or other external devices. (Eye-tracker and video recording equipment is not required as part of this procurement).

4.27.7 At a minimum, the following data elements shall be available for collection and recording:

4.27.7.1 Initial conditions (ex. weather, visibility, vehicle(s) type, positions, etc.)

4.27.7.2 Lane position

4.27.7.3 Lane deviation

4.27.7.4 Steering angle deviation

4.27.7.5 Velocity

4.27.7.6 Accelerator release time

4.27.7.7 Deceleration/Acceleration rate (pedal displacement) in response to presentation of stimuli (e.g., appearance of signals or crossings, sound of a trains horns, etc.)

4.27.7.8 Brake onset time

4.27.7.9 Brake pressure (pedal displacement) in response to presentation of stimuli (e.g., appearance of signals or crossings, sound of a trains horns, etc.)

4.27.7.10 Brake release time

4.27.7.11 Headway (distance and time) from subject vehicle to vehicle traveling ahead

4.27.7.12 Occurrence collisions or incidents

4.27.7.13 Time from the beginning of simulation

4.27.7.14 Time when a trigger is activated

4.27.7.15 Time when stimulus is presented (e.g., appearance of signals or crossings, sound of a train horn, etc.)

4.27.7.16 Time when stimulus disappears from view or earshot

4.27.7.17 Time to collision (lead vehicle and other vehicles in the simulator)

4.27.7.18 Time from stimulus onset to take evasive action

4.27.8 Data output should be a single file with each trial logged with data elements (including those elements listed above) in separate columns and samples for a given trial in the rows.

4.27.9 The vendor will provide a list of all information logged in the data output file and provide a clear explanation for each item (i.e. a key clarifying what is meant by each column name).

4.27.10 Columns in data output files must be labeled with titles that fit the following requirements:

4.27.10.1 No longer than 8 characters

4.27.10.2 One word (no spaces)

4.27.10.3 Must start with a letter. The remaining characters may be any letter, digit, a period or the symbols #, @, _, or $. No other special characters can be used

4.27.10.4 Cannot end with a period

4.27.10.5 Each name must be unique and indicative of the data it is representing.

4.28 The software and simulator must remain fully functional after support activities have concluded; use must not be contingent upon purchase of extended of support and maintenance.

5 Installation The Contractor shall provide on-site installation at the Volpe Center, Cambridge, MA. On-site installation shall include:

5.1 Place monitors, driver seat, steering wheel and pedals in intended position

5.2 Connect all components (monitors, driver seat ,steering wheel and pedals, computers and power sources) Ensure that all cables are protected and away from walking paths

5.3 Install and synchronize software as needed

5.4 Two copies of a user guide shall be provided with delivery of the system: a hard copy in 3-ring binders and a digital copy via CD or other mobile media. The user guide shall be written in English and include instructions for all requirements found in Section 4B entitled “Experimental Capabilities.”

5.5 The contractor shall submit warranty documentation, via CD or other mobile media, for all components delivered (contractor proprietary components as well as any third party hardware, software).

6 Demonstration and Government Acceptance

The Government considers the demonstration to be the basis for acceptance. Government acceptance is considered completed when the requirements in this section are met.

The contractor shall:

6.1 Demonstrate that volume can be controlled, sounds can be uploaded, and that the sounds from the ‘right’ (e.g., train approaching from the right side) are emitted through the ‘right-side’ speaker and that sounds from the ‘left’ are emitted through the ‘left-side’ speaker.

6.2 Demonstrate that all visual channels are displaying correct input (left, center, right).

6.3 Demonstrate that steering wheel and pedals reflect drivers input.

6.4 Demonstrate that driver inputs are recorded in data acquisition system.

6.5 Demonstrate user interface for the functionality requirements for highway-rail grade crossing applications (e.g., gates, lights, signs, pavement markings).

6.6 Be prepared to demonstrate that the simulator performs all the functions described in section 3 (Hardware Requirements and Physical Configuration). The Government may select all or random functions to be demonstrated.

6.7 Be prepared to demonstrate that the simulator performs all the functions described in section 4 (Software Requirements). The Government may select all or random functions to be demonstrated.

6.8 Be prepared to demonstrate that the provided documentation describes proper configuration, and use of all operations. The Government may select all or random operations to demonstrate.

7 Training

7.1 The contractor shall develop and provide a 5-day Driving Simulator training class to be conducted at the Volpe Center, Cambridge, MA. Training shall be completed within 30 days of Government acceptance. The Volpe Center will provide access to a projector, monitor, and training room. The contractor should provide a laptop computer and wireless internet card. The Contractor shall provide handouts of the training materials for 15 people. Training will be scheduled during regular business hours (i.e., 9 AM to 5 PM) at Government discretion. . Training shall cover, at a minimum, the following topics:

7.1.1 How to add objects and vehicles to the simulator;

7.1.2 How to create and import new traffic signs;

7.1.3 How to create events and coordinate the interaction between various elements in the simulation;

7.1.4 How to add and play sound files;

7.1.5 How to collect, record, and export data for analysis; and

7.1.6 How to specify data elements to be recorded (e.g. lane position, time when a trigger is activated, etc.).

7.1.7 Review system architecture, hardware. and computer connections for Volpe technical staff.

8 Technical Support and Software Maintenance

8.1 The contractor shall provide software and hardware technical support. Support shall be provided during regular business hours (i.e., 9 AM to 5 PM) via phone and e-mail. An initial response to technical issues shall be provided within 2 business days. A one year period of software and hardware support shall commence upon completion of training class.

8.2 The contractor shall provide software maintenance that includes all software updates (to be provided via CD or other mobile media), A one-year period of software maintenance shall commence upon completion of training class.

9 Option Year(s): Up to Two One-Year Options The contractor shall perform continued technical support and software maintenance as described in Section 8, Technical Support and Software Maintenance, when exercised by the government.

10 Schedule of Deliverables

DRAFT

Appendix A: Basic Highway-Rail Intersection Geometries (pavement marking and signs not shown)

Figure A-1. Highway-Grade Crossing Cross-Section. Source: A Policy on Geometric Design of Highway and Streets, 2004, by the American Association of State Highway and Transportation Officials, Washington, DC.

Figure A- 2. Highway-Railroad Crossing in Median

Figure A- 3. Highway-Railroad crossing near Horizontal Curve (single train track; two lane/two-way roadway)

Figure A-4. Single Train Tracks Intersecting a Two Lane/Two-Way Roadway

Figure A-5. Two Train Tracks Intersecting a Two Lane/Two-Way Roadway

Figure A-6. Diagonal Grade Crossing

Figure A-7 Diagonal Grade Crossing with Median Island between Crossings

Appendix B: Traffic Signs, Pavement Markings, and Signals for Highway-Rail Intersections Table B- 1. Grade Crossing Signs (Source: Manual on Uniform Traffic Control Devices, 2009 Edition. Washington, DC: Federal Highway Administration, 2009. Ch 8)

R10-6a May be used at locations where vehicles frequently violate the stop line or where it is not obvious to road users where to stop

Light Rail Only Right Lane Light Rail Only Left Lane Light Rail Only Center Lane R15-4a R15-4b R15-4c For multilane operations where roadway users might need additional guidance on lane use and/or restrictions.

Do Not Drive On Tracks Light Rail Symbol

Do Not Drive On Tracks R15-6 R15-6a Used where there are adjacent vehicle lanes separated from the LRT lane by a curb or pavement markings.

Light Rail Divided Highway Symbol

Light Rail Divided Highway Symbol (T-Intersection) R15-7 R15-7a

For Use with appropriate geometric conditions.

For Use with appropriate geometric conditions.

Collision experience Pedestrian presence

Low Ground Clearange Highway-Rail Crossing

As indicated by MUTCD guidelines, incident history, or local knowledge.

Shall be used only for crossings in FRA-authorized quiet zones

Storage Space XX Meters (Feet) Between Tracks & Highway Storage Space XX Meters (Feet) Between Highway & Tracks Behind You W 10-11a W10-11b Where the parallel highway is close to the crossing, particularly with limited storage space between the highway intersection and tracks.

Used where there is a highway intersection in close proximity to the highway-rail grade crossing and an engineering study determines that adequate space is not available to store a design vehicle(s) between the highway intersection and the train dynamic envelope.

Next Crossing

Use Next Crossing

Placed below the W10-5 sign at the nearest intersecting highway where a vehicle can detour or at a point on the highway wide enough to permit a U-turn.

Rough Crossing

If the highway-rail grade crossing is rough.

Figure B-1. Highway-Railroad Grade Crossing Sign (Crossbuck) and STOP or YIELD Sign on the Same Pole Source: Guidance for Use of YIELD or STOP Signs with the Crossbuck Sign at Passive Highway-Rail Grade Crossings. Memo issued by Jeffrey P. Paniati, Associate Administrator for Operations, and John R. Baxter, Acting Associate Administrator for Safety, Federal Highway Administration, Washington, DC, March 2006).

Figure B-2. Post-mounted flashing-light signal (two light units mounted in a horizontal line), a flashing-light signal mounted on an overhead structure, and an automatic gate assembly (strips on gate arms shall be vertical).

Figure B-3. Example of Placement of Pavement Markings and Advance Warning Signs image2.gif image3.png image4.png image5.gif image6.emf image7.emf image8.emf image9.emf image10.emf image11.emf image12.emf image13.emf image14.emf image15.emf image16.emf image17.emf image18.emf image19.emf image20.gif image21.emf image22.emf image23.emf image24.emf image25.emf image26.emf image27.emf image1.png