VII - Adjacent Intersections: Pre Signals and Preemption

VII - Adjacent Intersections: Pre Signals and Preemption

Module Learning Outcomes
Introduction Chapter1 Module Learning Outcomes Describe Solutions for Grade Crossings with Adjacent Intersections: Pre-Signals Queue Cutters Preemption Describe Timing Calculations List Possible Traps that can occur with preemption 2

Outline Introduction Pre Signals and Queue Cutters Pre-emption

NCHRP Synthesis 271: Traffic Signal Operations Near Highway-Rail Grade Crossings

Adjacent Intersections

Adjacent Intersections: Caltrain Standards
parallel roadways near crossings frontage roads adjacent to tracks Ideally, sufficient distance Not always the case Interactivity: Say: Adjacent intersections include parallel roadways near the crossings and frontage roads adjacent to the tracks. Ideally, there should be sufficient distance between the tracks and the adjacent roadway intersections to enable roadway traffic in all directions to move expeditiously. Notes: source - Caltrain Design Criteria Chapter 7 – Grade Crossings September 30, 2011

physically restricted areas Interconnection enables vehicles to clear Do Not Stop on Track No Left Turn traffic signal or signage Interactivity: Say: Where physically restricted areas make it impossible to obtain adequate vehicle queuing distance between the tracks and an intersection, the following should be considered: Interconnection of the roadway traffic signals with the grade crossing signals to enable vehicles to clear the grade crossing when trains approach, Placement of a “Do Not Stop on Track” signage on the roadway approach to the grade crossing, ‘No Left Turn’ traffic signal or signage on the frontage roadways

When a roadway intersection is located near a grade crossing special considerations include: A minimum of 75 feet Space for vehicles to escape if trapped Raised median islands Appropriate length for left and right-turn lanes Preemption time for both grade crossings pay attention to parallel streets, especially allowing left turn across tracks Interactivity: Say: When a roadway intersection is located near a grade crossing, such as when the railroad diagonally crosses one or two approaches, or crosses in the median of an intersection, special considerations should be considered in regards to roadway intersection geometry. A minimum space of 75 feet is required between the grade crossing gate and the roadway intersection to prevent large trucks from being trapped on the tracks that had advanced to the intersection, Space requirement for vehicles to escape on the far side of any grade crossing for vehicles that might be potentially trapped on the crossing when a train approaches the crossing. Use of raised median islands to prevent motorists from driving around the crossing gates. Evaluation of the appropriate length for left and right-turn lanes in order to avoid blockage of adjacent through lanes when the crossing gate arms are lowered for passing trains. Determination of preemption time for both grade crossings. The preemption time may have to be substantially lengthened. The designers shall pay particular attention to parallel streets, especially to those allowing a left turn across the tracks.

Pre Signals and Queue Cutters

Pre- Signals Separate Phasing/ Overlaps to Prevent Queuing
Across Tracks Located on Near Side of Tracks Mounted on Separate Mast Arm or Span Wire Used with “Stop Here on Red” Signs Pre- Signals Interactivity: Say: This graphics illustrates the location of pre-signals and passive signing supporting the intersection warning system. Note that two-quadrant gates, mast mounted, and the cantilevered standard traffic control signal. Also note that the roadway intersection control devices are located across from the parallel roadway. Signal faces operated as a part of the highway intersection traffic signals, located in a position that controls traffic approaching the railroad crossing and intersection supplemental highway traffic

Pre-Signal Location Upstream or downstream
Don’t interfere w/flashing lights Upstream pre-signals on cantilever, if permitted Minimum of two pre-signal faces at the crossing Traffic signals centered over each lane One set of pre-signals mounted on right side In median, minimum of 4ft 6in (but below flashing lights) Interactivity: Do: Carefully note each of the topics listed. Pre-signals may be a new concept to most of the class participants. Say: Located upstream or downstream from the railroad crossing Not to interfere with visibility of railroad flashing lights Upstream pre-signals mounted on cantilever, if present and permitted by the railroad and/or regulatory agency A minimum of two pre-signal faces at the crossing When mounted on traffic signal mast arms should be centered over each lane One set pre-signal faces mounted on right side of road In median mounted at a minimum of 4ft 6in above median island but below railroad flashing lights

Application of Pre-Signals with Gates
Interactivity: Say: The traffic engineer responsible for this intersection has attempted to aid the motorist, navigating through this maze of signals, by locating standard traffic signal at strategic points. Pre-signals, additional railroad signal heads, signing and pavement striping are all a part of the system. Even the pedestrian is given assistance by the gate arm at the sidewalk.

Application of Pre-Signals with Gates
Interactivity: Do: Discuss the type of mast or cantilevers needed, pros and cons Say: The standard traffic control signal is mounted over the inside traffic lane. Also note that the railroad signals are mast mounted. The cost of cantilever mounted railroad signals is substantial. The maintenance cost is excessive. Where possible standard traffic pre-signal signals, mounted over the approaching lanes should be considered.

Pre-Signals with Four Quadrant Gates
Interactivity: Say: The placement of these pre-signals, at or upon the railroad traffic control devices, may have been the result of a lack of space in the roadway approach. Note the horizontal curve suggesting a reduced traffic storage area near the track crossing.

Pre-Signals with Long Arm Gates
Interactivity: Say: At this intersection a single long arm gate is installed. Gate lengths exceeding 30 feet are difficult to keep in proper working order. The diagnostic team must pay particular attention to the need for median mounted gate systems as an alternative to excessive longer gate arms extending across all traffic lanes.

Pre-Signals and a Stop Bar
Interactivity: Say: Note the close proximity of the pre-signals to the railroad signals. Also point out the striped pavement area between the pavement STOP BAR and the track structure. The raised median discourages traffic from driving around the gates when in their down position. The traffic is stopped by the roadway traffic control system even though a train is not on the approach. (Gates are in the up position. Note the close proximity of the standard traffic signals to the track structure.

Middle of Street Crossing for Light Rail
Interactivity: Say: Tracks in the middle of the street present some unusual opportunities for the use of engineering judgment. With increased emphasis upon light rail and commuter rail this issue will become a major factor in traffic management systems in urbanized area. As shown here, the first step is to provide the motorist with a visual distinction between roadway and railroad operating ways. Different color an texture of the railroad structure is one option available.

Application of Pre-Signals
Interactivity: Do: Use this slide as a summary discussion of the pre-signal application. Note location of signal heads, pavement markings, signing and signal mounting.

Suggested customization: replace with local pics
Notes: Sample local pics from Missouri Course

Pre-Signals with Turning Lane
Interactivity: Say: Note that both the pre-signal and the railroad signal are cantilevered over the traffic lanes. Discuss location of RR pavement markings.

8C.09 Traffic Control Signals at or Near Highway-Rail Grade Crossings
STANDARD, GUIDANCE, and OPTION statements for the application of pre-signals Notes: The FHWA made the following changes: The FHWA adds additional GUIDANCE, STANDARD, GUIDANCE, and OPTION statements to better describe the use of pre-signals to improve safety at highway-rail grade crossings at locations in proximity to intersections controlled by traffic control signals. Additionally, the FHWA adds to the last OPTION statement that at locations where a highway-rail grade crossing is located more than 15m (50 ft) (or more that 23 m (75 ft) for a highway regularly used by multi-unit vehicles) from an intersection controlled by a traffic control signal, a pre-signal may be used if an engineering study determines a need. The FHWA feels that this addition may improve safety for this type of highway-rail grade crossing. The FHWA establishes a phase-in target compliance date of 10 years for existing installations to minimize any impact on State or local governments.

Queue-Cutter Signal Placement
SCRRA Highway-Rail Grade Crossings Recommended Design Practices and Standards Manual June 30, 2009

Indiana DOT Standards for Pre-Signals and Queue Cutters
Use Pre-Signals: Use Queue-Cutters: If Clear Storage distances are: 50 ft or less Up to 75 ft w/ high truck volume 50 to 120 ft with queuing analysis If Clear storage distances greater than 120 ft: VIDEO Interactivity: Do: Play the video Ask: Why do we need a queuing analysis to determine if pre-signal is the right application? Cue-cutter.wmv

Pre-signals and queue cutters with flashing red only (no gates)
Can use if only flashing lights are used But can result in conflicting signal indications On track clearance green Gates may be necessary Interactivity: Say: Pre-signals or queue-cutter signals can also be used wherever railroad warning devices consist only of flashing light signals. However, this can result in conflicting signal indications between the flashing red lights at the crossing and a display of track clearance green beyond the crossing. To eliminate this conflict, the installation of gates may be necessary. Notes: source: Institute of Transportation Engineers (ITE)

Queue Cutter Flashing-light Beacon
An alternative Can be used with signs Induction loop More effective than flashing continuously Interactivity: Say: An alternative to interconnecting two traffic control devices. Can be used in conjunction with DO NOT STOP ON TRACKS signs. Can be activated by an induction loop. Can be more effective as opposed to flashing continuously.

Pre-emption

Preemption - video Preemption.wmv Interactivity:
Do: Play video and discuss Ask: What is traffic signal preemption? Say: The transfer of normal operation of traffic signals to a special control mode (NEMA TS-2) Ask: Why pre-empt traffic signals close to railroad crossings? Say: To clear any vehicles that may be in danger of being hit by the train before the train arrives at the crossing.

Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See: Good Reference

Interactivity: Say: These are the four phases of preemption. Do: Go through each phase. The amount of warning time needed will be calculated in later slides. Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Preemption: Benefits Federal Railroad Administration:
Only? Notes: Traffic Signal Preemption Percent Impact = only 1.82, Percent Reduction 0.0 Limited data was available for this factor. Incidents at crossings with warning devices connected to highway traffic signals were queried from the RAIRS Grade Crossing database. The number of crossings with traffic signal preemption was available from the Crossing Inventory database, but it was not possible to distinguish the number of crossings equipped with traffic signal preemption by year. Therefore, the effectiveness of traffic signal preemption could not be analyzed sufficiently. Another approach was taken involving the position of the highway vehicle during an incident at a crossing equipped with traffic signal preemption. The position of interest was trapped. A vehicle could become trapped on a grade crossing by stopped traffic due to a red traffic signal ahead. Traffic signal preemption could reduce the risk of traffic queuing onto a crossing. However, no data was available to determine the reason the vehicle became trapped. Since the number of preempted crossings makes up less than 2 percent of overall crossings, and the percentage of incidents at preempted crossings did not change over the 10-year period, it was decided not to further pursue this factor. Percent impact is the percent of all incidents that the factor is attempting to address. Percent reduction is a percentage of the percent impact. Federal Railroad Administration: Success Factors in the Reduction of Highway-Rail Grade Crossing Incidents from 1994 to 2003

Preemption: Inspection
Federal Railroad Admin: Technical Bulletin S-12-01: Guidance Regarding the Appropriate Process for Inspection of Highway-Rail Grade Crossing Warning System Preemption Interconnections with Highway Traffic Signals Notes: source:

Types of Preemption Simultaneous Advanced
Notification of train to highway and railroad signal/warning devices Advanced Notification to highway signal controller prior to activating railroad devices. Difference in max preemption time for highway signal and min warning time needed for railroad. Interactivity: Say: Stress the difference between Simultaneous and advanced preemption. Simultaneous Notification of an approaching train is forwarded to the highway traffic signal controller unit and railroad active warning device at the same time. Advanced Notification of an approaching train is forwarded to the highway traffic signal controller unit or assembly by railroad equipment for a period of time prior to activating the railroad active warning devices. The period of time is the difference in the maximum preemption time required for highway traffic signal operation and the minimum warning time needed for railroad operations and is called the advance preemption time. CAt the end of the discussion of this slide ask a class member to briefly explain the two systems and how they differ.

Preemption Design Elements
Distance between the tracks and signal Intersection and crossing geometry Approach speed of trains and vehicles Train frequency Vehicle flow rates Vehicle size and classification Operation of the traffic signal control unit Interactivity: Stress: the factors to be considered in the selection of preemption control circuitry.

The Traffic Engineer Designing the Preemption Must:
Understand how controller operates in response to call Consult with railroad personnel Establish continuous cooperation to ensure compatibility Interactivity: Say: The Traffic Engineer Designing the Preemption Must: Understand how the traffic signal controller unit operates in response to a call for a preemption sequence Consult with railroad personnel responsible for railroad signal design Establish continuous cooperation with railroad personnel to ensure full compatibility between highway and railroad traffic control devices Note: This slide to be discussed in detail only when there are specific questions regarding engineering design.

Establish continuous cooperation …
Interactivity: Say: This is a label to be placed inside the signal control cabinet to warn signal technicians/engineers of potential hazard in re-programming the controller

Traffic Control Preemption
Within 200 feet of crossing Preempt to avoid entrapment First priority: train Second priority: emergency vehicle Interactivity: Say: Except under unusual circumstances, preemption should be limited to the highway intersection traffic signals within 60 m (200 feet) of the grade crossing. When the grade crossing is equipped with an active traffic control system, the normal sequence of highway intersection signal indications should be preempted upon approach of trains to avoid entrapment of vehicles on the crossing by conflicting aspects of the highway traffic signals and the grade crossing signals. This preemption feature requires an electrical circuit between the control relay of the grade crossing warning system and the traffic controller. The circuit shall be of the closed circuit principle, that is, the traffic signal controller is normally energized and the circuit is wired through the grade crossing warning system. This is to establish and maintain the preemption condition during the time that the grade crossing signals are in operation. Where multiple or successive preemption may occur from differing modes, train actuation should receive first priority and emergency vehicles second priority.

Crossing Signed for No Preemption
Interactivity: Say: While reconstruction, or maintenance, of the intersection is in process it may be necessary to disconnect the preemption attribute. Where signal preemption has been temporarily discontinued due to maintenance or construction, the motorist should be advised of the lack of preemption for train movements. Although this sign may not have much meaning to the average motorist this may be one of those instances where “good engineering judgment” should prevail.

Additional Considerations for Preemption
Upgrade from passive to active control High speed trains Tracks in medians Steep geometry Hazmat or buses Upgrade from stop to signal Interactivity: Say: A review of factors to be considered in conducting an engineering study to determine the need for, and the type of, preemption to be implemented. A crossing equipped with passive control devices only, may need to be upgraded to active warning systems. Where; near signalized intersection; high speed train operates; tracks in highway medians; steep grade geometry or where special vehicles such as hazardous material haulers or school buses operate. Where a crossing with active devices is in close proximity to an intersection with STOP-sign control it may be necessary to install traffic signals to clear queues from the crossing.

Preemption Design References
MUTCD Communications & Signal Manual, AREMA Traffic Control Devices Handbook Preemption of Traffic Signal Near Railroad Crossings, Institute of Transportation Engineers (ITE) Guidance on Traffic Control Devices at Highway-Rail Grade Crossings FHWA Guide for Traffic Signal Preemption near railroad grade crossings Timing Issues for Traffic Signals Interconnected with Highway‐Railroad Grade Crossings Success Factors in the Reduction of Highway-Rail Grade Crossing Incidents from 1994 to 2003 Interactivity: Say: It is important that both the roadway traffic engineer and the railroad signal engineer (signal maintainer) understand the significance of coordination between the two traffic control system. These are a few of the references that include technical information regarding the installation and operation of preemption systems. Manual on Uniform Traffic Control Devices U.S. Department of Transportation, Federal Highway Administration, Millennium Edition Communications & Signal Manual AREMA Communication and Signal Division, Highway Grade Crossing Warning Systems, Section 3, American Railway Engineering & maintenance of Way Association Traffic Control Devices Handbook Institute of Transportation Engineers, 2001 Preemption of Traffic Signal Near Railroad Crossings Institute of Transportation Engineers, 2003 Guidance on Traffic Control Devices at Highway-Rail Grade Crossings Federal Highway Administration Working Group, November, 2002 Guide for Traffic Signal Preemption near railroad grade crossings- Timing Issues for Traffic Signals Interconnected with Highway‐Railroad Grade Crossings - Success Factors in the Reduction of Highway-Rail Grade Crossing Incidents from 1994 to

Upstream Intersection Controlled by Passive Device
Interactivity: Discuss: the design of the traffic control system for this intersection. Note that there is an entry road in advance of the track crossing. That intersection is controlled by a passive device.

Illustration of narrow space for vehicle storage beyond the crossing
Interactivity: Say: This illustrates the narrow space for storing vehicles beyond the track and before entry into the intersecting roadway. Ask: What is wrong and what could be done to improve this situation (change stop sign to yield, provide warning sign of limited storage space, …)

Standard Traffic Signals in Lieu of Flashing Lights?
Interactivity: Say: Highway traffic control signals shall not be used on mainline railroad crossings in lieu of flashing light signals. However, at industrial track crossings and other places where train movements are very slow (as in switching operations), highway traffic control signals may be used in lieu of conventional flashing light signals to warn vehicle operators of the approach or presence of a train.

Interactivity: Say: Where train speeds are less than 32 km/h (20 mph). A switching operation. Signals can be controlled by “key operation.”

Interactivity: Say: To supplement railroad traffic control devices. On separate support. To provide positive green indication when train is not approaching or occupying the intersection.

Cantilevered Traffic Signal, without Gate
Interactivity: Say: Major roadway facility. Secondary railroad facility. Supplement railroad traffic control devices. Positive green when railroad signals are not activated.

Masthead Mounted Traffic Signals
Interactivity: Say: The Mast Method for Locating Signals over the Travel Lanes.

Interactivity: Say: The Cantilever Method for Locating Signals over the Travel Lanes.

Tutorial Interactivity:
Do: Go through each step of the tutorial with the students. This would make an excellent exercise if the instructor would bring copies of the paper and supplemental materials for designing the preemption timing. Notes: Source: Gary Long, Transportation Research Record p239 Paper No

Preemption Sequence Prior to train arrival
Call registered for Railroad; Entry into preemption Controller lag time or programmed delay Right-of-way transfer interval (RTT) Track clearance interval (TCG) Train present on crossing Call remains Preemption hold interval (dwell) or limited service Train departs crossing Exit from preemption Interactivity: Say: Source: Gary Long, Transportation Research Record Paper No

ROW Transfer Time Interval (RTT)
RTT: time required to terminate any phase(s) conflicting with track clearing phase TCG Includes: Controller lag time or programmed delay required clearance times per MUTCD Policy decisions for truncating: Minimum Green Walk and Pedestrian clearance times (if present) Shortening Red Revert (Amber back to Green)

Determining the Time Needed to Clear a Queue
(1) Determine whether the signalized intersection is within 200 ft of the railroad crossing, as specified in the MUTCD, or whether expected maximum queues are likely to extend back as far as the track such that traffic signal preemption for queue clearance is needed.

(2) Identify the appropriate design vehicle in compliance with MUTCD.

(3) Obtain the design length and acceleration category of the design vehicle by consulting Table 1. Interactivity: Say: Table 1 from the paper

(4) Determine the minimum track clearance distance in compliance with MUTCD. Interactivity: Say: Figure 1 from the paper ’ for perpendicular tracks

(5) Determine the clear storage distance in compliance with MUTCD.

(6) Add the minimum track clearance distance and the clear storage distance to get the critical queue length.

(7) Enter Figure 2 with the critical queue length and get the expected progressive startup delay.

(8) Add any needed special adjustments for non-ideal factors such as… conflicting left-turn stragglers intersection turning-vehicles inhibited by sharp corner radii or obtuse turning angles or pedestrians drivers distracted or inattentive interferences by vehicles turning at adjacent driveways other Interactivity: Say: conflicting left-turn stragglers that deter the startup of lead vehicles, intersection turning-vehicles inhibited by sharp corner radii or obtuse turning angles or pedestrians, drivers distracted by surrounding activities, inattentive drivers, interferences by vehicles either turning in or out of adjacent driveways, or other factors. Limited information on departures from ideal conditions is presented elsewhere.

(9) Add the design vehicle length and the minimum track clearance distance to get the repositioning distance.

(10) Enter Figure 3 with the repositioning distance, the design vehicle type and acceleration category (and grade if the design vehicle is a combination truck) and get the expected maximum repositioning time.

(11) Add the expected maximum startup delay and expected maximum repositioning time to get the expected safe track-clearance time. + Interactivity: Say: The total time needed to clear the queue is 50 seconds. The track signal system must be able to provide at least this much warning.

(12) Add the train-detection equipment-delay time, pedestrian minimum truncation time, yellow change interval time, train separation time and other necessary time adjustments to the expected safe track-clearance time

See also … Texas Method, Appendix I of the Grade Crossing Handbook

Preemption Traps #1 Failed Preempt Trap #2 Advance Preempt Trap
#3 Second Train Trap #4 Yellow Trap Interactivity: Say: There are several ways a vehicle may become trapped on the tracks if there is faulty preemption. Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Preemption Trap #1 Failed Preempt Trap
See “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems Preemption Trap #1 Failed Preempt Trap Line is cut Signals Preempted Railroad Controls and Warning Devices Functional Worse than No Preemption Appears Normal, so there is no notification of a problem! Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

How do we avoid Failed Preempt Trap?
Detect Failure (Supervised Circuit) Add Special Preemption Sequence for Failed Condition to Ensure Safe Operations Make Failed Preempt Higher Priority Automatically Notify of Failure Immediately Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Preemption Trap #2 Advance Preempt Trap
Occurs with Advance Preemption Preempt May Occur When Signal is already in TCG or When RTT is less than maximum TCG expires prior to warning lights begin to flash Vehicles begin queueing onto tracks Track clear has expired and now dwells in Preemption Hold, potentially with vehicles on tracks! No better than having no preemption at all… Notes: – Right-of-way transfer interval (RTT) – Track clearance interval (TCG) Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Preemption Trap #2 Advance Preempt Trap
Occurs with Advance Preemption Preempt May Occur When Signal is already in TCG or When RTT is less than maximum TCG expires prior to warning lights begin to flash Vehicles begin queueing onto tracks Track clear has expired and now dwells in Preemption Hold, potentially with vehicles on tracks! Notes: – Right-of-way transfer interval (RTT) – Track clearance interval Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See: (TCG)

Potential Solutions for Advance Preempt Trap:
Truncate pedestrian clearance to reduce Max RTT Request two preempt inputs to the signal controller for each train arrival and Incorporate “gate down” signal from railroad warning device into preemption sequence (extend track clearance phase until gates are down) Use a special phase for track clearance to control Minimum RTT Make Track Clear Green time greater than the APT Notes: – Right-of-way transfer interval (RTT) – Track clearance interval (TCG) Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Preemption Trap #3 Second Train Trap
First train clears crossing Gates rise, motorists begin crossing Signal remains preempted for 2nd train Preempt Hold Vehicles Trapped on Crossing 2nd Train Arrives Solution: Signal controller must recognize second preempt call and restart preemption- RTT, TCG Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Preemption Trap #4 Yellow Trap
Occurs with pre-signals with trailing overlaps Controller ends pre-signal & opposing approach phase simultaneously; the signals for the same direction as the pre-signals change 3-4 seconds later Left-Turning Driver assumes opposing traffic’s phase is ending as well; opposing traffic has green for 3-4 seconds longer Driver makes left turn into opposing traffic. Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Solution: Run phase for approach opposite the track crossing on a trailing overlap using dummy phases (never displayed) so the signal heads at the intersection end together. Notes: From “Traffic Signal Advance Pre-emption Design within 200 Feet of Active Railroad Crossings” INDOT Division of Traffic Control Systems See:

Module Learning Outcomes
Introduction Chapter1 Module Learning Outcomes Describe Solutions for Grade Crossings with Adjacent Intersections: Pre-Signals Queue Cutters Preemption Describe Timing Calculations List Possible Traps that can occur with preemption Photo source: 85

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VII - Adjacent Intersections: Pre Signals and Preemption

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