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Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways (2007)

Chapter: Chapter 5 - Traffic Control Devices

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Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
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Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
×
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Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
×
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Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
×
Page 17
Page 18
Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
×
Page 18
Page 19
Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
×
Page 19
Page 20
Suggested Citation:"Chapter 5 - Traffic Control Devices." National Academies of Sciences, Engineering, and Medicine. 2007. Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways. Washington, DC: The National Academies Press. doi: 10.17226/23171.
×
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14 Traffic control devices are essential complements to the design and operations of busway intersections. They assign right-of-way to conflicting movements of buses, motor vehi- cles, pedestrians, and bicyclists; specify permitted and pro- hibited movements; and provide other necessary information and guidance. They include traffic signals, active and passive signs, pavement markings, and gates. This chapter is based primarily on the MUTCD (10). Intersection Control General Considerations At-grade busway crossings can be classified as signalized, stop-controlled, yield-controlled, or uncontrolled intersec- tions. Most busway intersections in North America are signal controlled for all users at the intersection. However, there are a few stop-controlled intersections, including some intersec- tions along the South Miami-Dade busway, and a few uncon- trolled midblock pedestrian crossings. Signalization is the preferred method of control for busway intersections because it provides clear right-of-way assign- ment. However, for some intersections, particularly separated right-of-way busway intersections, signalization may not be warranted. The relatively low volume of buses on the busway may not be sufficient to warrant signalization based on Sec- tion 4C.01 of MUTCD. Although buses generally have a higher occupancy than motor vehicles, signalization warrants are currently based on the number of vehicles, not the num- ber of persons. A person-based warrant has been proposed to the National Committee on Uniform Traffic Control Devices (NCUTCD) for this and similar situations; however, it has not yet been accepted into the MUTCD. The development of a person-based warrant is desirable for busway intersections and should be considered further. In conducting the engineering study to determine if a signal is warranted, pedestrian volumes at the intersection and their increase once the busway is completed should be considered. Stop-Controlled Busway Intersections If an intersection cannot be signalized, stopping cross- street traffic is preferred in the interest of busway operations. The type of stop control (i.e., two way or four way) depends on the volume of the intersection, the available gaps, and sta- tion placement. In most cases, stopping the cross-street traf- fic without stopping the busway traffic is not practical because the cross-street volumes are likely much higher than the busway volumes. Conversely, because of the length and driving characteristics of most busway vehicles, finding an acceptable gap in the cross-street traffic may be difficult for bus operators at intersections where only busway traffic is stop controlled. Therefore, four-way-stop control may be necessary. Separated right-of-way busway intersections may lack some of the visual cues of an intersection including the pres- ence of cross-street traffic. At these intersections, care must be taken to ensure that the intersection control is communicated to the users and that the intersection is clearly identified. Sup- plementary traffic control devices such as flashing beacons, transverse rumble strips, advance Stop Ahead signs, or Stop Ahead pavement markings may be necessary. Because the operating characteristics of a bus on a busway are comparable to light rail operation, Section 10C.04 of the MUTCD, which provides guidance for the use of stop control at light rail crossings, should be reviewed when selecting the appropriate intersection control for busways. Notably, this section provides guidance that stop control be used when light rail transit speeds do not exceed 40 km/h (25 mph). Signal-Controlled Busway Intersections Currently two types of traffic signals are used to control buses at busway intersections: standard vehicle signals and light rail transit signals. Light rail transit signals are the pre- ferred type of control for the buses on the busway, although some agencies use standard vehicle signals. Engineering C H A P T E R 5 Traffic Control Devices

judgment that considers the surrounding environment should be used to select the appropriate signal display. The South Miami-Dade Busway is an example of a busway that uses standard vehicle signals to control buses at the inter- sections. Buses approaching the intersection are controlled by the same standard red-yellow-green signals that are used for general vehicle traffic. The agencies who use this type of sig- nal note that, because buses are also vehicles, the signal for the buses should be a standard signal. If standard traffic signals are used, care should be taken to ensure that the bus signal indications are not visible by other movements. If other movements can see the bus signal indi- cation, they may mistake the bus indication for their own. This potential is particularly a concern for median busway intersections and side-aligned busway intersections. For example, at median intersections, if left-turning vehicles on the parallel roadway mistake the busway green for their own, they may turn across the path of an approaching bus. The Richmond 98 B-Line, which uses standard signals for bus control, experienced a problem with left-turning vehi- cles when the system first opened. To mitigate this safety concern, the signals were changed to programmable signals so that the parallel general traffic could not see the bus signal indication. Guidance for the use of light rail signals to control light rail transit vehicles can be found in Section 10D.07 of the MUTCD. The light rail signal indications, which are illumi- nated white bars, are displayed in Figure 5-1. These signals are subsequently referred to as white bar signals to avoid confu- sion with light rail applications. 15 Source: MUTCD Section 10D.07 (10). Figure 5-1. Light rail transit signal indications.

The Orlando Lynx LYMMO system is an example of a busway that uses white bar signals for the busway intersec- tions. An example of a bus signal in Orlando’s system is pro- vided in Figure 5-2. If white bar signals are used, all bus operators who will travel on the busway need training in the meaning of the sig- nal indications. If an operator has not driven the route recently, he or she may need a refresher course in the signal indications. Training also may be needed for others who may use the busway, for example, emergency or maintenance vehi- cle drivers. Additionally, because pedestrians often take their cue from vehicle signals when pedestrian signals are not pres- ent at an intersection, all intersections should be equipped with functioning pedestrian signals. The following questions should be considered when select- ing the type of traffic signal to use at busway intersections: • Will other users (e.g., maintenance vehicles) of the busway have to interpret the signal indication? • Can the signal indications be viewed by other users at the intersection, particularly at night or in high-wind condi- tions when programmable visibility signals may become misaligned? • Is there a benefit to having wayward motorists or other unauthorized users be able to interpret the signal indica- tion to ensure a safe exit from the busway? • Does the use of white bar signals help to differentiate the busway from other lanes at the intersection? Intersection traffic control for general-purpose traffic at busway intersections is the same as non-busway intersections. Additional traffic controls may be installed to prohibit certain movements at busway intersections. Such controls may include dynamic right- or left-turn prohibition (e.g., bus- activated, internally illuminated signs). Pedestrian and other non-motorized users should be con- trolled by pedestrian signals, particularly if white bar signals are used as previously discussed. Pedestrian countdown dis- plays may be useful on pedestrian signal controls. These dis- plays count down the number of seconds remaining in the pedestrian change interval. Countdown signals are particu- larly beneficial at median busway intersections where transit passengers depart the intersection from a median station and may not need the entire pedestrian clearance interval to cross the remaining half of the intersection. Static and Active Signs Signs are used to convey various types of information to all users at busway intersections. Signs can be used to • Deter unauthorized entry, • Provide advance warning of the busway crossing, • Warn of approaching buses, • Identify the busway, • Deter vehicles from queuing over the busway, • Prohibit certain movements at the intersection, and • Identify the appropriate traffic signal head to the associated movement. These regulatory, informational, and warning messages are primarily communicated to intersection users with static signs. Active signs also can be helpful when it is espe- cially important to attract the attention of motorists and pedestrians. Because of the additional information that needs to be conveyed at busway intersections, more signs are needed than at traditional intersections. Care should be taken to avoid visual clutter, which contributes to motorist confusion, at busway intersections. Deterring Unauthorized Entry At the entrances to the busway for all three major types of intersections (i.e., median, side-aligned, and separated) and bus-only ramps, a Do Not Enter (MUTCD designation R5-1) sign should be used on the right-hand side of the busway to deter unauthorized entry. The MUTCD allows for a second Do Not Enter sign on the left side of the busway, particularly where traffic approaches from an intersecting roadway. The sign should be supplemented with a Transit Vehicles Exempt plaque. Some agencies have used additional signs to indicate which vehicles are authorized on the busway. A simple sup- plementary plaque accomplishes the objective of precluding transit vehicles from the Do Not Enter sign with the least amount of visual clutter. At separate-alignment intersections or at some closely spaced side-aligned intersections, turn prohibition signs are 16 Figure 5-2. Orlando LYMMO’s bus signal.

appropriate including No Turns (R3-3), No Right Turn (R3-1), and No Left Turn (R3-2). Internally illuminated signs may also be appropriate when turn prohibitions are conditional based on an approaching bus or during a certain signal phase. Some agencies also use signs that display information about the penalties associated with unauthorized entry to the busway and No Motor Vehicles signs (R5-3). The use of these signs should be considered in relation to the amount of visual clutter at the intersection. Additionally, transit vehicles are motor vehicles. To provide a clear, concise message to drivers, No Motor Vehicles signs should be placed elsewhere and should not be used at busway intersections. Warning Signs Advance warning signs that identify the presence of the busway intersection are useful at separated busway intersections and at some closely spaced, side-aligned intersections. They are not needed at median arterial busway intersections. Currently, the MUTCD has not defined an advance warn- ing sign for busway crossings. Therefore, a few agencies have developed their own advance warning signs. The Los Angeles Department of Transportation (LADOT) developed a stan- dard diamond-shaped, yellow advance busway crossing sign. This sign is displayed in Figure 5-3. The bus graphic on the sign is based on the outline of the Orange Line buses. The Florida Department of Transportation has also devel- oped a similar sign based on the South Miami-Dade buses. At separated busway intersections, advance traffic control signs may be necessary to warn of the upcoming traffic con- trol device. These signs include the Stop Ahead (W3-1), Yield Ahead (W3-2), and Signal Ahead (W3-3) signs. A warning beacon may be used with these signs to emphasize the mes- sage. At signalized intersections, a Be Prepared to Stop (W3-4) sign may be useful if sight distance is limited, particularly if supplemented by a warning beacon that is interconnected with the traffic control signal. If it is interconnected, the sup- plementary plaque When Flashing should be used. Busway Street Name Signing The busway should have a sign or symbol that clearly identifies the busway intersection. Such a sign is particularly important for independent intersections or closely spaced, side-aligned intersections where conspicuity of the crossing is a concern. Based on the experiences of the busway operators surveyed, the sign could employ the same color and design as other road or street name signs in the area, although a larger sign may be desirable for increased visibility. Using similar color and design helps to reinforce the busway intersection as a legitimate intersection, deserving the same respect as other intersections.Another school of thought is to use a busway sign or symbol that is not the same in color and design as other road or street name signs. The reasoning for using a non-standard sign is to identify the busway intersection as a different type of intersection. Agencies may want to consider a non-standard sign if there is a large concern with vehicles accidentally turn- ing into the busway. In selecting the type of street name sign that is used, the agency should consider the unique character- istics of the intersection, the collective set of traffic control devices and other visual cues at the intersection, and the poten- tial for various unsafe maneuvers by intersection users. Right Turn on Red Prohibition Prohibiting right turns on red across the busway is critical to safe operation of side-aligned busway intersections. Vehi- cles that violate the right turn prohibition may conflict with approaching buses. The right turn prohibition must be clearly communicated to the motorists. Right turns can be prohibited with a graphical No Turn on Red (R10-11) or a non-graphical sign (R10-11a or R10-11b). The sign should be installed near the appropriate signal head. In situations where the busway phase is concurrent with the parallel through-traffic phase, a separate signal head and separate lane is needed for the right turn. TCRP Report 90: Bus Rapid Transit (11) adapted three signs from the MUTCD that may be useful for busway intersections to supplement other traffic control devices aimed at deterring right turns on red. The signs have been modified to depict parallel busways intersecting with cross-street traffic. These proposed warning signs are pictured in Figure 5-4. Traffic Signal Identification Signs to identify the traffic signals associated with certain movements at the intersection may be necessary. Left Turn 17 Figure 5-3. LADOT advance busway warning sign used at Orange Line intersections.

bus pedestrian warning sign, the same size and shape as the pedestrian signal, is mounted adjacent to the pedestrian sig- nal. It is presented in Figure 5-6. An LED (light-emitting diode) indication of the front of a bus flashes when a bus is approaching the crossing. The effectiveness of this device is unknown; however, one author expressed concern that pedestrians may confuse the flashing bus sign with the flash- ing raised hand of the pedestrian signal. A steady bus indica- 18 Figure 5-5. Bus signal sign mounted next to bus signal at intersection of Orange Line busway, Los Angeles. Source: TCRP Report 90, Volume 2 (11). Figure 5-4. Three proposed traffic signs for busway intersections based on light rail signs. Figure 5-6. Bus-activated warning sign (black with orange symbol) for pedestrian midblock crossings of Orange Line busway, Los Angeles. Signal signs (R-10L) are useful at median busway intersec- tions for the left-turn movements across the busway from the general-purpose lanes. Right Turn Signal signs (R-10R) are useful for right turns from parallel roadways at side-aligned busway intersections. At median arterial intersections, the busway signal also may need to be identified with a Bus Sig- nal sign. An example of a bus signal sign at an Orange Line intersection in Los Angeles is presented in Figure 5-5. Signs Directed at Pedestrians, Bicyclists, and Other Non-Motorized Users The signs directed at non-motorized users that deter pedestrians from crossing at inappropriate locations, identify designated crossing locations, and provide information on the use of pedestrian push buttons (e.g., R9-3a, R9-3, and R10-3b) are the same at busway intersections as at traditional intersections. The LADOT developed a special warning sign for use at pedestrian midblock crossings of busways. The approaching-

tion, or a sign that flashes and then becomes steady, may be more appropriate. Pavement Markings Pavement markings with the words “BUS ONLY”should be used at the entrance to the exclusive busway (Figure 5-7). This marking will help to deter unauthorized entry into the busway as a supplement to signs. Some agencies in North America use other, similar messages on the pavement to identify the busway lanes; however, the words “BUS ONLY” convey the message in a simple and concise manner. It may be beneficial to use pavement markings in the actual intersection to deter vehicles from queuing over the busway intersections. Such queuing is particularly a concern at side- aligned intersections. Some intersections along the Orange Line busway in Los Angeles have pavement markings with the words “KEEP CLEAR.” Cross-hatching in the intersection may produce the same effect. As noted previously, median arterial busway intersections are wider than traditional intersections. In such intersections, pavement markings can be used to guide left-turning motorists through their turns, will help to keep them from turning into the busway. Cleveland plans to use raised, red pavement reflectors to deter motorists from turning left into their median busway from the cross streets. The reflectors will be placed on a 45-degree diagonal across the entrance to the busway. Motorists turning left will see the red indication of the reflectors during their turn. This application of pavement reflectors is potentially useful for other median arterial busway intersections. Other Traffic Control Devices Automatic Gating Considerations Automatic crossing gates such as those used at some light rail transit (LRT) at-grade crossings have been discussed as a potential traffic control device to separate conflicting move- ments at busway intersections. Crossing gates are currently not used at busway intersections in North America. Section 10D.03 of the MUTCD provides guidance that, on highway-LRT at-grade crossings, automatic crossing gates should be used together with flashing-light signals where light rail vehicle speeds exceed 60 km/h (35 mph). If used for busway intersections, gates would be placed across the path of cross- street traffic in advance of the busway intersection to physically deter entry into the intersection during the busway phase at sep- arated or some side-aligned intersections.Crossing gates are not practical for cross-street traffic at median arterial intersections. Issues to be considered regarding the use of crossing gates include efficiency, placement, liability, maintenance costs, con- sistency in use,and motorist and pedestrian compliance.Cross- ing gates will reduce the overall efficiency of the intersection. The time required to raise and lower the gates adds lost-time to the cycle length at signalized intersection and increases inter- section delay at both signalized and unsignalized intersections. For some busway intersection alignments, the placement of crossing gates would not be useful. For example, the cross- street traffic entering the median busway intersection does not need further deterrent than that provided by parallel traf- fic at traditional intersections because the busway operates in the median of the general-purpose lanes. At side-aligned busway intersections, right-turning vehicles from the parallel mainline is the primary concern rather than cross-street traf- fic, which crossing gates control. The following concerns regarding automatic gates were expressed by the agencies interviewed: • Liability for damages could arise from the failure of the automatic gates. • If the gates were used at one intersection, they would need to be used at all intersections. • The cost to install and maintain these devices would be prohibitive. • Pedestrians and some motorists may not comply with the gates if they were used for a busway instead of a light rail crossing. Agencies may be held liable for any damages that arise from the failure of automatic gates. If crossing gates are used at one intersection, they may need to be used al all intersections. The cost to install and maintain these devices would be prohibi- tive. Also, pedestrians and some motorists may not comply with the gates if they are used for a busway instead of a light rail crossing. 19 Figure 5-7. “BUS ONLY” pavement markings at LYMMO intersection, Orlando, Florida.

Gates may be appropriate at bus-only ramps to deter unau- thorized entry. This application is different from the crossing gate applications that would prevent vehicles from traveling across the busway. Instead, the gates would be placed at the entrance to the ramp and would remain down until an approaching bus activates them and would close shortly after the bus enters. In summary, automatic gates diminish the efficiency of intersection operations and may be a liability or maintenance issue. They may be applicable at bus-only ramp entrances where there are intrusion issues. Their application should be evaluated on a case-by-case basis. Colored Pavement Colored pavement may be an effective traffic control device to deter unauthorized entry into busways and increase the visibility of busway intersections. Many busway agencies in North America indicated they would like to use colored pave- ment but cited cost as the leading reason it was not used. Some busway agencies used other methods to differenti- ate the busway pavement from the side or cross-street pave- ment. The Orlando LYMMO system uses a distinctive gray, textured pavement to differentiate the bus lanes. The Los Angeles Orange Line has installed concrete pavement at intersections. The contrast in color from the concrete of the intersection and the asphalt concrete of the travel lanes increases the visibility of the busway intersections. Although not a busway, the San Francisco LRT uses red pavement for the first 50 feet on a median alignment. The rest is standard concrete. Summary Table 5-1 presents suggested traffic control devices by type of busway intersections. Additional traffic control devices that may be useful are presented in italics. 20 Table 5-1. Suggested traffic control devices at busway intersections by type of busway. Purpose of Traffic Control Device Median Busways Separate Right-of-Way Busways Side-Aligned Busways Bus-Only Ramps Control Basic Movements White bar signals Standard or white bar signals White bar signals Uncontrolled Prohibit Unauthorized Entry Dual Do Not Enter (R5-1) signs with supplementary Transit Vehicles Exempt plaque Bus Only pavement markings Diagonal red reflectors Keep Clear sign or similar in intersection Dual Do Not Enter (R5-1) signs with supplementary Transit Vehicles Exempt plaque Bus Only pavement markings No Turns (R3-3) sign No Right Turn (R3-1) sign No Left Turn (R3-2) sign Keep Clear sign or similar in intersection Dual Do Not Enter (R5-1) signs with supplementary Transit Vehicles Exempt plaque Bus Only pavement markings No Turns (R3-3) sign No Right Turn (R3-1) sign No Left Turn (R3-2) sign Keep Clear sign or similar in intersection Dual Do Not Enter (R5- 1) signs with supplementary Transit Vehicles Exempt plaque Bus Only pavement markings Warning N/A Advance Busway Crossing Sign (undesignated) Advance Busway Crossing Sign (undesignated) N/A Identify Intersection Color or textured pavement “Busway” using standard street signing convention Color or textured pavement “Busway” using standard street signing convention Color or textured pavement Color or textured pavement Prohibit Right Turn on Red N/A N/A No Turn on Red (R10-11 or R10-11a) sign Modified LRT (W10-2b) signs Modified LRT blank-out (R3- 1a) sign N/A Identify Traffic Signal (if used) Bus Signal sign Left Turn Signal (R-10L) sign if arrow is not used N/A Right Turn Signal (R-10R) sign if arrow is not used N/A

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TRB’s Transit Cooperative Research Program (TCRP) Report 117: Design, Operation, and Safety of At-Grade Crossings of Exclusive Busways explores planning, designing, and operating various kinds of busways through roadway intersections. The report examines at-grade intersections along busways within arterial street medians; physically separated, side-aligned busways; busways on separate rights-of-way; and bus-only ramps. The intersections highlighted include highway intersections, midblock pedestrian crossings, and bicycle crossings. Appendixes A through I of the contractor’s final report were published as TCRP Web-Only Document 36.

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