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Task Analysis of Rail-Highway Grade Crossings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14-2 Driver Information Needs at Passive Rail-Highway Grade Crossings . . . . . . . . . . . . . . . . . .14-4 Timing of Active Traffic Control Devices at Rail-Highway Grade Crossings . . . . . . . . . . . . .14-6 Four-Quadrant Gate Timing at Rail-Highway Grade Crossings . . . . . . . . . . . . . . . . . . . . . . .14-8 Countermeasures to Reduce Gate-Rushing at Crossings with Two-Quadrant Gates . . . . .14-10 Human Factors Considerations in Traffic Control Device Selection at Rail-Highway Grade Crossings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14-12 14-1 C H A P T E R 14 Rail-Highway Grade Crossings
T AS K A NA LY SI S OF R AI L -H IG HW AY G RA DE C RO SSI NG S In tr od uc ti on This guideline addresses the key factors found to affect driver decisions regarding whether to obey traffic control devices at rail-highway grade crossings. Most crossings have traffic control devices (TCDs) installed and yet vehicle-train crashes still occur. From 1998 to 2007, 24,609 crashes occurred at pub lic crossings that had warning devices installed ( 1 ). One reason that crashes occur is that individual factors cause drivers to disregard traffic control devices and put themselves into situations where there is a conflict risk. Although these factors are unique to each driver, the inform ation provided by the crossing warnings can support safe decision-ma king. De si gn Gu id e lin es The following table provides inform ation and guidelines for addressing fa ctors that a ffect com pliance with traffic control devi ces at rail-highway grade crossings. The following guidelines should be considered in order to im pr ove stopping/yielding behavior and reduce vehicl e-train crashes. Factor Guideline Driver Fam iliarity Consider active devices if warranted. Expectations Alert drivers that the crossing is operational (if it is). Credibility Only use active warning devices in environm ents where they can provide warnings of a predictable, constant length. Reliability Use reliable warning devices. TCD Design/ Roadway TCD ti mi ng Balance active warning tim ing so that it is long enough to provide enough ti me for driver s to ma ke a go/no-go response, but not so long as to decrease co mp liance. Guideline: Ti mi ng of Active TCDs at Rail-Highway Grade Crossings (p. 14-6) TCD selection TCD selection should support the time available for the driver to ma ke a go/no-go decision given the sight lines at the crossing. Guideline: Human Factors Considerations in TCD Selection at Rail-Highway Grade Crossings (p. 14-12) Train speed perception When drivers mu st judge the speed of an approaching train head-on (as from a Stop Sign at the crossing), train speed perception cues should be provided. Guideline: Human Factors Considerations in TCD Selection at Rail-Highway Grade Crossings (p. 14-12) Sight lines Support driver decision-m aking by providing sight lines consistent with the requir em ents of the TCD. Guideline: Human Factors Considerations in TCD Selection at Rail-Highway Grade Crossings (p. 14-12) T AS K A NA LY SI S FO R R AI L -H IG HW AY G RA DE C RO SS IN GS Based Primarily on Expert Ju d g ment Based Equally on Expert Judgment and Empirical Dat a Based Primarily on Empirical Dat a Compliance Issue HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0 14-2
Discussion Many of the driver factors that are incorporated into this guideline are covered in more detail in subsequent guidelines. It is important to consider these factors when planning a crossing because ultimately drivers decide whether they will comply with a warning device. Familiarity: Abraham, Datta, and Datta (2) observed vehicles at train crossings and mailed surveys to the violators. They found that, of the drivers who violated the warning device, 68% traversed the specific crossing at least four times per week and 19% crossed two to four times per week. Expectations: Raslear (3) performed an analysis of train detection at rail crossings using signal detection theory and compared the results to those found using crash data. Both analyses confirmed that if drivers expected to see a train at the crossing (and/or trains passed through more frequently), they were less likely to get in an accident. Credibility: The level of trust that a driver has in the timing of the warning device is affected by the length of time that the driver has to wait, and the consistency of this time. Generally, as the warning time increases, the number of violations increases (4). Drivers expect a train to arrive within a certain amount of time after the activation of the warning devices. Additionally, constant warning-time systems (rather than fixed-distance systems) have been shown to decrease mean warning times and increase compliance (4). Reliability: Reliability is characterized by the accuracy with which an active warning device indicates that a train is approaching every time a train is coming and only when a train is coming. Gil, Multer, and Yeh (5) used a simulator to test participant responses at a crossing with a single-quadrant automatic gate, after participants were primed on the reliability of the traffic control device. Gil et al. found that as the probability that a warning device actually indicated the presence of a train decreased, the frequency of gate violations increased (5). Although in the simulator, participants were biased towards proceeding regardless of the warning reliability (perhaps due to time-based completion incentives), indicating the possibility of the influence of other motivational factors. Design Issues Gate-rushing is a specific type of violation that has been observed where drivers drive around gates that are closed or gates that are in the process of closing when trains are near the rail-highway grade crossing (6). There is no indication as to why drivers choose such a risky maneuver; they may be in a hurry, think they have enough time to pass, or have found the gate to be unreliable in the past. This behavior may be explained by some of the driver factors described in this guideline, or it may be related to other additional factors. Countermeasures regarding gate-rushing are discussed in âCountermeasures to Reduce Gate-Rushing at Crossings with Two-Quadrant Gatesâ on page 14-10. The degree to which the driver holds the train operator accountable for the driverâs crossing safety also affects crossing compliance (7). Drivers tend to think that train operators share some of the responsibility for crossing safety, i.e., if a driver and the train reach the crossing at the same time, the driver assumes that there is a shared responsibility for collision avoidance. Advisory speed signs can be confusing to drivers if they are unaware of the reason for the reduced speed. Cross References Rail-Highway Grade Crossings Guidelines, 14-1 Key References 1. Raub, R.A. (2009). Examination of highway-rail grade crossing collisions nationally from 1998 to 2007. Transportation Research Record, 2122, 63-71. 2. Abraham, J., Datta, T.K., & Datta, S. (1998). Driver behavior at rail-highway crossings. Transportation Research Record, 1648, 28-34. 3. Raslear, T.G. (1995). Driver behavior at rail-highway grade crossings: A signal detection theory analysis. In A.A. Carroll & J.L. Helser (Eds.). Safety of Highway-Railroad Grade Crossing. Research Needs Workshop. Volume II - Appendices (DOT/FRA/ORD-95/14.2p. 46 p.). Washington, DC: U.S. Department of Transportation. 4. Yeh, M., & Multer, J. (2007). Traffic control devices and barrier systems at grade crossings: Literature review. Transportation Research Record, 2030, 69-75. 5. Gil, M., Multer, J., & Yeh, M. (2007). Effects of Active Warning Reliability on Motorist Compliance at Highway-Railroad Grade Crossings (DOT-VNTSC-FRA-09-04. DOT/FRA/ORD-09-06). Washington, DC: Federal Railroad Administration. 6. Khattak, A.J., & McKnight, G.A. (2008). Gate rushing at highway-railroad grade crossings: Drivers' response to centerline barrier. Transportation Research Record, 2056, 104-109. 7. Richards, S.H., & Heathington, K.W. (1988). Motorist understanding of railroad-highway grade crossing traffic control devices and associated traffic laws. Transportation Research Record, 1160, 52-59. 14-3 HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0
D RIVER I NFORMATION N EEDS AT P ASSIVE R AIL - H IGHWAY G RADE C ROSSINGS Introduction This guideline refers to the information that drivers need to behave safely at rail - highway grade crossings that are protected by passive devices. This is especially relevant for crossings with only passive protection since drivers carry the full responsibility of determining if a train is approaching. In the past, crossings have bee n marked by crossbucks alone; however, the crossbuck is now required to be accompanied by a Yield or Stop sign ( 1 ). Yield and Stop signs address many of the deficiencies of crossbucks by more directly and effectively fulfilling driver information needs. Design Guidelines This guideline provides recommendations regarding the type of information that should be presented at rail - highway grade crossings protec ted by passive warning devices. If the rail-highway grade crossing is protected by passive warning devices, verify the following information (2): A. Existence of a rail-grade crossing ahead. B. Passive status of the crossing, so it is the driverâs responsibility to determine if a train is at or near the crossing. C. Actions that are required of the driver (e.g., maintain speed, slow down, look for trains). D. If there are special conditions that require more driver attention (e.g., limited sight distance, skewed crossing). The following signs and plaques provide information to help meet some of the driver information needs listed above. These signs and plaques are presented in addition to traditional Stop and Yield signs, as discussed on the following page. The signs are labeled as they are in the 2009 MU TCD and include the information need(s) that they satisfy in parentheses. E XAMPLES OF P ASSIVE S IGNING TO F ULFILL D RIVER I NFORMATION N EEDS (N OT TO S CALE ) W10 - 1 ( A ) W10 - 13P ( B ) R15 - 8 ( B, C ) W10 - 15P ( D ) W10 - 12 ( D ) R15 - 2P ( D ) W10 - 9P ( D ) Source: FHWA ( 1 ) Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0 14-4
Di scu ssi on The inform ation needs described in the guideline on the previous page are not adequately addressed by crossbuck warning devices alone. The signs and plaques provided are examples of countermeasures that can be used to fill som e of these needs. However, the effectiveness of the various signs in improving driver safety is unknown. An additional, required sign element at passive crossings is the Yield or Stop sign. The following table shows ways in which Yield and Stop signs address the deficiencies of crossbucks in providing inform ation needs (adapted from Lerner, Llaneras, McGee, and Stephens ( 2 )). The information needs are labeled as listed in the table on the previous page. Information Need Crossbuck Deficiency Yield or Stop Sign Mitigation A. Existence of rail- grade crossing ahead Lacks conspicuity. Yield (or Stop) adds red color, greater retroreflective surface area, and icons with high target value. Ineffective for non-English-literate drivers. Well-understood icons for Yield and Stop. Unclear indication of th e point of intersection between the roadway and track. Understood that Yield (or Stop) is located at the intersection. B. Passive status of the crossing, so the driver has the responsibility to look for a train Fails to distinguish driver requirements for active vs. passive crossings. Presence of Yield (or Stop) indicates passive crossing. Difficult to distinguish active vs. passive crossings on approach. Well-understood distinct advance signs for Yield and Stop. Lack of a clear indication of need and responsibility to search. Yield is understood to mean search for conflicting vehicles. C. Actions that are required of the driver. Fails to induce appropriate slowing. Yield is understood to require slowing. Poor comprehension of regulatory meaning of crossbuck. Meaning of Yield (or Stop) is well understood. Stop-look-listen fallacy. Clearly distinguishes when mandatory stop is required; Yield does not imply stop. D. Special conditions that warrant attention. Coping with special demands, unusual features. Advance signing for hazards, under well-defined conditions of presentation. It is evident that Yield and Stop signs address the driverâs inform ation needs mo re thoroughly than crossbucks alone. Lerner et al. ( 2 ) suggests the use of a Yield sign unless a Stop sign is warranted to reduce the likelihood of train-vehicle conflicts. To fulfill the objective of providing clear guidance to drivers, Lerner et al. ( 2 ) supports the use of two additional plaques to be displayed below the existing Grade Crossing Advance Warning Signs. These plaques would convey the status of the upcoming warning devices, either active or passive. The passive plaque reads âNo Signals or Gates,â while the active plaque shows an icon of a flashing-light signal with the words âSignal Ahead.â The addition of the new plaques would provide information to drivers regarding the status of the upcoming traffic control devices on the approach to the crossing. The current MUTCD has a si mi lar passive warning plaque (W10-13P), which is optional, but does not support the active plaque. De si gn Is su es Olson, Dewar, and Farber ( 3 ) include another list of driver information needs: (1) something is there, (2) the item that the driver sees is a train, (3) the train will cross the road that the driver is on, (4) the distance to the train, and (5) the trainâs speed and direction. These needs would likely be difficult to meet using passive signage. However, they highlight th e significance of environmental contextual cues as an addition to engineering countermeasures to help the driver interpret their surroundings. These driver inform ation needs also highlight the limitations of Yield signs, especially under am biguous circum stances. Cr os s Re fe re nc es Human Factors Considerations in Traffic Control Device Selection at Rail-Highway Grade Crossings, 14-12 Ke y Re fe re nc es 1. FHWA (2009). Manual on Uniform Traffic Control Devices for Streets and Highways. Wash ington, DC. 2 Lerner, N.D., Llan eras, R.E., McGee, H.W., & Stephens, D.E. (2002). NCHRP Report 470: Traffic-Control Devices for Passive Railroad- Highway Grade Crossings. Washington, DC: Transportation Research Board. 3. Olson, P.L., Dewar, R., & Farber, E. (2009). Forensic Aspects of Driver Perception and Response . Tuscon, AZ: Lawyers & Judges. 14-5 HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0
TIMING OF ACTIVE TRAFFIC CONTROL DEVICES AT RAIL-HIGHWAY GRADE CROSSINGS Introduction This guideline refers to the warning time, or the time between the initiation of the flashing light traffic control devices and the arrival of the train. If the total warning time or portions of the timing are too short, drivers are at a risk of not being able either to stop in time for the gates to descend or to pass over the crossing from the dilemma zone. On the other hand, if the warning time is too long, drivers are less likely to comply with the warning devices (1). Design Guidelines The following graph of active traffic control device timings should provide adequate time for drivers to stop or to cross when appropriate (adapted from 1). WARNING TIMES FOR RAIL-HIGHWAY GRADE CROSSINGS ⢠If twin or triple tractor-trailer combinations are expected, increase the minimum and optimal times by 10%. ⢠If more than 10% of the warning times exceed the maximum times, motion sensors or train predictors should be installed to reduce warning times. Gates should be considered for flashing light crossings and four-quadrant gates should be considered for two-quadrant enforced crossings. ⢠All of the warning times for crossings with gates include gate delay/descent time. The graphic below shows in more detail the recommended signal and gate timing for two-quadrant gates. SIGNAL AND GATE TIMING FOR TWO-QUADRANT GATES Source: Richards & Heathington (1), FHWA (2) Flashing Light Signals only Flashing Light Signals and Two- Quadrant Gates 0 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 35 45 55 65 75 85 95 105 115 Crossing Width (length of hazard zone, ft) Maximum Approach Grade (%) 35 s minimum 35-40 s optimal 40 s maximum 35 s minimum 35-40 s optimal 60 s maximum 30 s minimum 30-35 s optimal 30 s minimum 30-35 s optimal 60 s maximum 25 s minimum 25-30 s optimal 40 s maximum 30 s minimum 30-35 s optimal 60 s maximum 20 s minimum 20-25 s optimal 40 s maximum 20 s minimum 20-30 s optimal 60 s maximum Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data Time (s) 0 10 20 30 50 60 7040 Gate delay Gate descent Train delay Train passing Gate ascent Optimal range Maximum range Absolute maximum HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0 14-6
Di scu ssi on Warning times: Richards and Heathington ( 1 ) conducted field observations and a laboratory study to deter mi ne the expectations of drivers for warning ti me s at rail-highway grade crossings. Driver observations were made using video tape at three crossings that had relatively high volumes of train a nd vehicle traffic as well as so me past accidents. The crossings had flashing light signals or flashing light signals and standard gates. At the crossings with only flashing light signals, mo st drivers crossed without stopping if they arrived within 1 s of the warning period beginning. This proportion steadily decreased and leveled off around 4 s, when most drivers stopped. However, at the crossings with both gates and flashing light signals, most drivers did not react to the light activation and tried to beat the gate. More than 60% of the drivers crossed without stopping 9 s into the warning period. The percentage of drivers who stopped only leveled off when they could no longer beat the gates. The total warning ti me is compos ed of the gate delay, gate descent, and train delay times (for crossings with gates). Gate delay and gate descent: The gate delay is defined as the length of ti me between the start of the flashing lights and the initiation of the descent of the entry gate ( 3 ). The percentage of drivers who cross without stopping increases with increasing gate delay/descent time ( 1 ) . As the co mb ined time increased fro m 10-14 s, the percentage of drivers who did not stop increased dramatically to level off at around 50% at a 15-s combined time. Thus, the authors recommend that the combined gate delay and descent period should optim ally be between 10 s and 12 s, with an absolute maximu m of 15 s. The MUTCD ( 2 ) requires that the gate ar m start its descent at least 3 s after the start of the flashing lights. Richards and Heathington ( 1 ) give an upper lim it of 4 s to this value, except when vehicle approach speeds exceed 60 mi/h. Train delay: The train delay is the amount of time between the gate descent and the train arrival. At the crossings with only flashing light signals, 98% of drivers stopped and remained stopped for warning ti me s of 20-25 s, 73% for tim es of 25-30 s, and 90% for tim es of 30-35 s. Beyond 35 s, driver stopping behavior declined rapidly and when warning times exceeded 80 s, less than 20% of drivers stopped. At the gate d crossing, 90% of drivers stopped and remained stopped for warning times of 20-25 s, 70% for times of 25-30 s, and 60% for ti me s of 30-35 s. Beyond 35 s, the percentage stopped re ma ined constant around 60%, with a sharp drop after 80 s. At the crossing with only flashing light signals but no predictors, generally long warning ti me s led to compliance percentages below 30% for all warning times. Even when the warning times matched those at signalized crossings with predictors, compliance was mu ch lower, perhaps due to a holdover effect that long and variable warning ti me s have on general driver behavior at specific crossings. Within this warning ti me , the MUTCD ( 2 ) requires that the gate ar m reach a horizontal position at least 5 s before the train arrives at the crossing and remain down for the duration of the time that the train is at the crossing. Additionally, the MUTCD provides the standard that flashing-light signals should operate for at least 20 s before the arrival of a train under mo st circumstances. In a follow-up laboratory study ( 1) , drivers viewed videos of train crossings and noted when they expected the train to arrive and when the elapsed ti me without a train arrival had become too long. When comparing flashing-light-only crossings to those with gates, the expected train arrival times are approximately the same (14.5 s to 13.2 s) when gate delay and descent are not included. The me an train delay to be considered excessive was 66.2 s for the gated crossing (including gate delay and descent) and 48.8 s without gate delay and descent times. This time was significantly longer than that for the flashing-light-only cr ossing at which a 39.7-s delay was considered excessive. Gate ascent : The MUTCD ( 2 ) provides the guidance that the gate ar m should ascend to the vertical position in 12 s or less after the train clears the crossing (if no other train traffic is detected). After the gate ar m ascends, the flashing light si g nals and lights on the gate arms should extinguish. De si gn Is su es A caveat of this research is that few observations occurred when large vehicles were present. The times presented are based upon driver behavior rather than stopping distance calculations, which vary based on vehicle size. Also, only one gated crossing was included in the study done by Richards and Heathington ( 1 ). Cr os s Re fe re nc es Task Analysis of Rail-Highway Grade Crossings, 14-2 Human Factors Considerations in Traffic Control Device Selection at Rail-Highway Grade Crossings, 14-12 Ke y Re fe re nc es 1. Richards, S.H. & Heathington, K.W. (1990). Assess me nt of warning tim e needs at railroad-highway grade crossings with active traffic control. Transportation Research Record, 1254, 78-84. 2. FHWA (2009). Manual on Uniform Traffic Control Devices for Streets and Highways . Wash ington, DC. 3. Colem an, F., III. & Moon, Y.J. (1996). Design of gate delay and gate interval tim e for four-quadrant gate system at railroa d -highway grade crossings. Transportation Research Record, 1553, 124-131. 14-7 HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0
FOUR-QUADRANT GATE TIMING AT RAIL-HIGHWAY GRADE CROSSINGS Introduction This guideline refers to the gate interval time, which is the length of time between the initiation of the descent of the entry gate and the initiation of the descent of the exit gate at a crossing with a four-quadrant gate device (1). The gate interval needs to be long enough to allow even large vehicles to finish passing over the crossing before the second gate closes, but not so long that vehicles will try to bypass the first gate to beat the train through the crossing. Design Guidelines The following equations can be used to calculate gate delay and gate interval times at four-quadrant gates (1). Gate operation time = Gate delay + Gate interval time Where: t = driver perception-reaction time (PRT, s) v = approach speed (m/s) a = deceleration level on level pavement (m/s2) G = acceleration resulting from gravity (m/s2) g = grade of approach lanes (percent/100) D = distance between stop bar and gates (m) L = length of the vehicle (m) Wght = distance between entry and exit gates (m); for calculation see below For 90Ë: For > 90Ë: Where: Wght = distance between entry and exit gates (m) Wt = width of railroad track (m) Wh = width of approaching lane of the highway (m) Wg = distance from track edge to gate (m) = crossing angle (degrees) Single Railroad Track* Multiple Railroad Tracks* *Graphics adapted from Coleman & Moon (1). Exit Gate Highway Entrance Gate Entrance Gate Railroad Track Exit Gate Stop Bar Stop Bar D L Wh Wg α Wt Exit Gate Highway Entrance Gate Entrance Gate Railroad Track Exit Gate Stop Bar Stop Bar D L Wh Wg α Wt Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0 14-8
Di scu ssi on Four-quadrant gates are desirable for their ability to restrict through traffic at grade crossings. Four-quadrant gates are more effective at controlling gate-rushing, that is passi ng around gate arm s that are already descended on two - quadrant gates (see âCountermeasures to Reduce Gate-Rushing at Crossings with Two-Quadrant Gatesâ on page 14-10). The MUTCD ( 2 ) guidance suggests that four-quadrant gate systems should only be used at crossings that are equipped with constant warning ti me detection. A critical operational element of such syste ms is the operation of the exit gate arm. The exit gate arm must be timed in such a way that it is still effective against drivers attempting to dr iv e in the opposing direction around the entry gate, yet it does not trap vehicles trying to clear the crossing in the proper lane between the two gate ar ms . The MUTCD ( 2 ) defines the exit gate clearance time as âthe am ount of tim e provided to de lay th e descent of the exit gate arm(s) after entrance gate arm(s) begin to descend,â equivalent to the gate interval time in this guideline. The MUTCD ( 2 ) also describes two operating m odes for the exit gate arm s. The Timed Exit Gate Operating Mode has a predetermined gate interval time, while The Dynamic Exit Gate Operating Mode bases the gate operation on the presence of vehicles within the mi ni mu m track clearance area. For either operating mo de, the exit gate clearance time, or gate interval time, should be considered when determining the warning time. The timing guidance provided by the MUTC D ( 2 ) states that the gate ar ms blocking the entrance lanes should begin their descent no less than 3 s after the flashing lights begin flashing and reach the down position no less than 5 s before the train arrives. Exit arm timing should be based upon detection or ti mi ng requirem ents as deter min ed by an engineering study. The design of this timing concept is based on the concept of the dilemma zone, similar to that at signalized intersections ( 1 ). When the flashing signal lights begin flashing at a grade crossing, the driver mu st decide if he/she needs to stop or can proceed through the crossing before the gates descend. There are three relevant distances involved in the decision: the distance between the driver and the crossing, the distance that the vehicle travels prior to the descent of the entry gates (continuation distance), and the stopping distance before the crossing. If the stopping distance and continuation distance are equal, the driver is at a âsafe decision locationâ where he/she may either stop or clear the crossing safely. This location is used to simplify the model. Although this model is based upon a single study, the met hodology was validated using six crossings under consideration for four-quadrant gates. Coleman and Moon ( 1 ) use perception-reaction tim es (t) of 1.0 s and 2.5 s in the model. Additionally, they cite a deceleration level (a) of 3.04 m/s 2 as found in intersection studies with approach speeds of 35 mi /h. The MUTCD guide states that, where possible, a safety zone able to accommodate at least one design vehicle should exist between the exit gate and the nearest rail (distance W g in this guideline). De si gn Is su es A dynamic dilemma zone has been defined in reference to intersections as âa road segment on approach to an intersection which varies in length based on fluctuations in vehicle speeds and the number of vehicles within a road segm entâ ( 3 ). The model is highly similar to the static dilemma zone model discussed in this guideline, but can account for vehicle accelerations/decelerations near the crossing and vehi cle platoon behavior. Cr os s Re fe re nc es Task Analysis of Rail-Highway Grade Crossings, 14-2 Tim ing of Active Traffic Control Devices at Rail-Highway Grade Crossings, 14-6 Countermeasures to Reduce Gate-Rushing at Crossings with Two-Quadrant Gates, 14-10 Ke y Re fe re nc es 1. Colem an, F., III. & Moon, Y.J. (1996). Design of gate delay and gate interval tim e for four-quadrant gate system at railroa d -highway grade crossings. Transportation Research Record, 1553, 124-131. 2. FHWA. (2009). Manual on Uniform Traffic Control Devices for Streets and Highways . Wash ington, DC. 3. Moon, Y. J., & Co lem an, F., III. (2003). Dynam ic dilem ma zone based on driver behavior and car-following model at highway-r a il intersections. Transportation Research Part B: Methodological, 37 (4), 323-344. 14-9 HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0
COUNTERMEASURES TO R ED UC E GATE -R US HI NG AT CROSS IN GS WI TH T WO -Q UA DR AN T G AT ES In tr od uc ti on Gate-rushi ng is a type of violation that occurs when drivers drive under gate arm s as they are descending or around gate arm s that are already in the lowered position. Although gates are so me of the mo st restrictive crossing control devices, 9.1 crashes per 1 mil lion trains are still occurring at crossings with two-quadrant gates ( 1 ). Additionally, vehicle crashes at gated crossings were significantly mo re likely to occur when a train struck a vehicle than when a vehicle struck a train ( 1 ). This is likely occurring because a driver ha s mi sjudged the speed of the train and rushed the gate(s) in an attempt to beat the train through the crossing. De si gn Gu id e lin es Use one or mo re of the counterm easures below to reduce gate-rushing at rail-highway grade crossings with two- quadrant gates. Co unte rm ea su re Ex am pl e Install centerline barriers (flexible barriers to separate traffic ( 2 )) Install a four-quadrant gate ( 3 ) Based Primarily on Expert Judgmen t Based Equally on Expert Judgment and Empirical Dat a Based Primarily on Empirical Da ta HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0 14-10
Discussion Centerline barriers: The two unsafe behaviors that were examined with centerline barriers were gate-rushing and driver U-turns while waiting for trains to pass through the crossing. When tested at two sites, centerline barriers reduced gate-rushing by 35% on average and U-turns at gates by 82% on average (2). The results showed that drivers were more likely to rush the gates in clear weather and when the gate malfunctioned (i.e., activated without a train present). Drivers were also more likely to bypass the gate when more than one train was crossing with little delay between them as many drivers used the gap between successive trains to go around the gate and cross. Drivers were also more likely to make U-turns with longer gate closures, gate malfunctions, in clear weather, on weekends, and when trains stopped on the tracks. The median treatment was only tested at two crossings; however, although the frequency of unsafe behaviors varied between the crossings (likely due to site-specific characteristics), driversâ responses to the barrier countermeasure were similar in magnitude between the two different crossings. Four-quadrant gates: Four-quadrant gates reduce gate-rushing by physically restricting drivers from driving around lowered gate arms. In a before-and-after study performed with a transition from two-quadrant to four-quadrant gates with skirts, the average number of drivers per train arrival who drove around the gate arms dropped from 2.6 to 0.0 (3). Driver approach speed was found to be about 10 mi/h faster with the installation of four-quadrant gates. This was likely due, however, to drivers not having to slow to follow a queue of vehicles that were bypassing the lowered gate arms. The authors recommend that four-quadrant gates be considered for crossings with one or more of the following characteristics: (1) crossings on four-lane undivided roads, (2) multitrack crossings at which the distance between tracks is greater than the vehicle length, (3) crossings without train predictors that have long and variable warning times, (4) crossings that are frequently crossed by trucks carrying hazardous materials, school buses, or high-speed passenger trains, and (5) crossings with consistent gate-rushing or crashes. Design Issues Engineering changes: There are engineering changes that can be made to reduce gate-rushing without the installation of additional physical roadway countermeasures. Constant warning time train predictors have been shown to reduce violations of flashing light signals and reduce the occurrence of very short clearance times at crossings with flashing lights only (4). Also, decreased warning times have been shown to reduce violations in general (5). For exact guidance, see the guideline on Timing of Active Traffic Control Devices at Rail-Highway Grade Crossings. These constant and decreased warning times improve the credibility of warning devices, thereby increasing driver trust in the system and compliance with warning devices. Wayside horns: In a study at three crossings in a residential suburb, Raub and Lucke (6) found that after the transition from train horns to automated wayside horns, gate violations decreased by 68%. Additionally, residential sound levels decreased by over 10 dB in most locations within the vicinity of the crossings. Although these are both great advantages for the wayside horn systems, the horns can have false activations (i.e., activated when a commuter train stopped at a station within the warning zone) and are often sounded for longer periods of time than train horns (from the time that the gate activates to the train arrival). There is the possibility that the horns may startle drivers as evidenced by 12 drivers that stopped on the tracks. Overall, the main purpose of this countermeasure is not to reduce gate-rushing, but rather to replace locomotive horns with an auditory notification that pollutes surrounding areas to a lesser degree. Cross References Task Analysis of Rail-Highway Grade Crossings, 14-2 Timing of Active Traffic Control Devices at Rail-Highway Grade Crossings, 14-6 Four-Quadrant Gate Timing at Rail-Highway Grade Crossings, 14-8 Key References 1. Raub, R.A. (2009). Examination of highway-rail grade crossing collisions nationally from 1998 to 2007. Transportation Research Record, 2122, 63-71. 2. Khattak, A.J., & McKnight, G. A. (2008). Gate rushing at highway-railroad grade crossings: Driversâ response to centerline barrier. Transportation Research Record, 2056, 104-109. 3. Heathington, K.W., Fambro, D.B., & Richards, S.H. (1989). Field evaluation of a four-quadrant gate system for use at railroad-highway grade crossings. Transportation Research Record, 1244, 39-51. 4. Richards, S.H., Heathington, K.W., & Fambro, D.B. (1990). Evaluation of constant warning times using train predictors at a grade crossing with flashing light signals. Transportation Research Record, 1254, 60-71. 5. Richards, S.H. & Heathington, K.W. (1990). Assessment of warning time needs at railroad-highway grade crossings with active traffic control. Transportation Research Record, 1254, 78-84. 6. Raub, R.A., & Lucke, R.E. (2004). Use of automated wayside horns for improving highway-rail grade crossing safety. ITE 2004 Annual Meeting and Exhibit. 14-11 HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0
HUMAN FACTORS CONSIDERATIONS IN TRAFFIC CONTROL DEVICE SELECTION AT RAIL-HIGHWAY GRADE CROSSINGS In tr od uc ti on This guideline refers to the human factors that apply to three different levels of control at rail-highway grade crossings: Yield signs, Stop signs, and automatic gates. The MUTCD ( 1 ) states that a Yield or Stop sign should be part of the crossbuck assem bly. The Yield sign is the de fault choice, however Stop si gns are currently the more prevalent traffic control device used at grade crossings ( 2 ). Interest in the use of Yield signs at passive crossings is increasing. Also, under certain conditions, the use of active control devices may be the most suitable solution. The following factors can be used when deter mi ning th e appropriate level of control. De si gn Gu id e lin es The table below outlines the human factors issues to consider when installing a Yield sign, Stop sign, or active control devic e . Driver Factor Yield Sign Stop Sign Active Control Sight lines ⢠Provide a large sight triangle ⢠Provide at minimum a sight triangle along the track ⢠Few requirements for sight lines Decision factors ⢠Low â driver needs information to ma ke a gap acceptance decis ion ⢠Medium â driver needs information to make a go/no-go decision ⢠High â driver needs little additional information Timing elements ⢠Provide enough time to decide to stop or continue while moving ⢠Provide clearance time for large vehicles that are stopped at the crossing ⢠Provide appropriate light timing to allow vehicles to stop or cross after flashing lights activate Workload ⢠High ⢠Medium ⢠Low Train speed perception ⢠Visual expansion and translational cues are provided ⢠Provide speed perception cues along the track â only visual expansion cues provided ⢠Not necessary for decision Decision zones (Graphics not to scale) Direction of traffic flow De ci si on Zo ne R AI L R O A D C R O S S I N G (Width of sight triangle only limited by roadside objects.) De ci si on Z one RA I L RO A D C R O SS I N G R AI L RO AD CR O S SI N G Based Primarily on Expert Ju d g men t Based Equally on Expert Judgment and Empirical Dat a Based Primarily on Empirical Da ta HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0 14-12
Discussion Compliance issues are not addressed in this discussion since they are covered in âTask Analysis of Rail-Highway Grade Crossingsâ on page 14-2 as well as the design issues section below. Exact guidance regarding when to install each control device can be found in the Highway/Rail Grade Crossing Technical Working Group document (3) and the MUTCD (1). Yield sign: The Yield sign provides the lowest level of control discussed in this guideline. The MUTCD standard states that a Yield sign should be the minimum additional level of control at passive grade crossings with crossbucks. The amount of information provided by a Yield sign is minimal since the location of the train (if present) and the appropriate driver action are not provided. As drivers are approaching the crossing, the decision they need to make is similar to a gap acceptance decision; they need to judge the gap between their vehicle and the train (if present) to determine if yielding is required. To make this judgment, a large clear zone is necessary in the approach area to enable drivers to see the train from a distance that allows them to stop or proceed. However, this means that drivers will have better speed perception cues than they do at Stop signs, since they observe the train from a greater distance from the crossing. They receive not only the visual expansion cues, but also translational cues from the trainsâ forward motion. Because a stop is not required at Yield signs, all of the decision making occurs farther before the crossing than it does for the Stop sign. Additionally, drivers have greater latitude in their decision making than they do at crossings with a greater level of control. This puts a demand on drivers to judge their speed relative to a moving train and decide the safe action. Stop sign: The Stop sign provides an intermediate level of control between the Yield sign and active gates. The sign requires drivers to stop and then to make a go/no-go decision based upon the presence of a train. Since drivers are making the go/no-go decision while stopped at the tracks (at a later point than they do for the Yield sign), the demands for sight lines are less significant and occur along the track. However, while looking almost straight down the tracks, drivers have poor speed perception of the oncoming train. Additionally, from the stopped position, larger vehicles take longer to accelerate over the tracks, which they need plenty of time to do before the train arrives. This puts a demand on the sight distance of the train to give drivers time to make a go decision and then cross the tracks. Active Gates: Active traffic control devices with gates provide a high level of control, thus removing most of the decision-making demands from drivers. Drivers have few requirements in the way of sight lines because they know if a train is approaching by the status of the device. Train speed perception cues are not necessary since the active device warns that a train is approaching. In terms of vehicle kinematics, the timing of the gate should give drivers enough time to stop or proceed as appropriate before the gate descends. A related device is flashing lights without gates. This device also removes most of the decision-making demands from the driver but does not provide a physical barrier between the vehicle and the crossing. Design Issues Compliance and other internal factors can largely affect driver decision-making at traffic control devices in various ways. At Yield signs, low train expectancy and/or high familiarity with the crossing can lessen the degree of visual search performed on the approach. At Stop signs, low train expectancy and/or high familiarity can push for a âgoâ decision or decrease stopping occurrences. Additionally, Sanders, McGee, and Yoo (4) state that the driver should be able to perceive that a stop is necessary and enforcement should equal that of a Stop sign at a highway intersection. If a Stop sign is present, the driver should not be able to detect a train without stopping at the sign. For active control devices, low credibility or reliability, as discussed in âTask Analysis of Rail-Highway Grade Crossingsâ on page 14-2, can contribute to gate-rushing. Cross References Task Analysis of Rail-Highway Grade Crossings, 14-2 Timing of Active Traffic Control Devices at Rail-Highway Grade Crossings, 14-6 Four-Quadrant Gate Timing at Rail-Highway Grade Crossings, 14-8 Key References 1. FHWA. (2009). Manual on Uniform Traffic Control Devices for Streets and Highways. Washington, DC. 2. Lerner, N. D., Llaneras, R. E., McGee, H. W., & Stephens, D. E. (2002). NCHRP Report 470: Traffic-Control Devices for Passive Railroad-Highway Grade Crossings. Washington, DC: Transportation Research Board. 3. Highway/Rail Grade Crossing Technical Working Group (TWG) (2002). Guidance on Traffic Control Devices at Highway-Rail Grade Crossings. FHWA. Retrieved July 2011 from http://safety.fhwa.dot.gov/xings/collision/. 4. Sanders, J.H., McGee, H.W., & Yoo, C.S. (1978). Safety Features of Stop Signs at Rail-Highway Grade Crossings. Volume II. Technical Report (FHWA-RD-78- 41). Washington, DC: FHWA. 14-13 HFG RAIL-HIGHWAY GRADE CROSSINGS Version 2.0
