CHAPTER 6
Findings and Future Research Needs

This chapter summarizes the findings of the synthesis project. It also presents suggested guidance from agencies that have implemented or operate red-tinted bus lanes and identifies future research needs.

Findings

Planning, Design, and Implementation

Several agencies implemented their first red-tinted bus lanes as pilot projects. These agencies reported that pilot projects can be useful for testing specific red-tinting materials, specific red-tinting designs, and different implementation techniques. They noted that pilot projects can also be useful in building partnerships.

Some agencies observed that an advantage of using red-tinting treatments to distinguish bus lanes is that they do not interfere with bus maneuverability. Curbs and delineators can reduce violations and call extra attention to bus lanes, but they can also be too restrictive for bus operators in the event that the bus lane is blocked (e.g., by a parked car).

Funding is a concern across the board for agencies that have implemented red-tinted bus lanes. Funding affects planning, design, implementation, operation, enforcement, and maintenance.

Some agencies have used intermittent and partial-width red-tinting designs to save on material installation and future maintenance costs. The agencies indicate that these designs have been effective in decreasing bus lane violations.

While the 11th edition of the MUTCD allows red tinting in part-time bus lanes, there are inconsistent views across agencies about the suitability of red tinting for part-time bus lanes and the red-tinting design (e.g., continuous or intermittent) appropriate for part-time bus lanes.

The method used to apply red-tinting materials can affect installation time and the quality of the resulting red-tinting treatment. Agencies that have implemented red-tinted bus lanes have reported learning lessons along the way by experimenting with equipment and application methods. One agency reported that it initially applied MMA with a sprayer but that the sprayer was not reliable for the scale of application. On later projects, the agency applied MMA by hand, which—while slower—also resulted in a higher-quality treatment.

Some agencies have found design standards and specifications for red-tinted bus lanes to be useful in implementing the lanes in a consistent manner. The standards and specifications also serve to formalize the agencyʼs experience of what red-tinting materials and designs work best in local conditions.

Materials

According to the survey described in this report, the most common red-tinting treatments currently used in North America are red MMA, red thermoplastic, and red HFSTs with color-coated glass aggregate. Factors that influence an agencyʼs choice of red-tinting treatments include:

• Applying treatments in the correct season and under the correct weather conditions (e.g., in warm and/or dry conditions),
• Contractor or agency staff familiarity with a given red-tinting treatment,
• Coordination with other jurisdictions,
• Cost of implementation (including labor and equipment),
• Cost of maintenance (including frequency as well as labor and equipment needs),
• Cost of the product,
• Durability (expressed in terms of limited fading, adequate adherence to a given pavement surface, and sustained skid resistance in the local climate),
• Effectiveness of the product (expressed in terms of lane-usage compliance and visibility in different conditions),
• Environmental impacts,
• Expected lifespan of the product (on a given pavement surface and in the local climate),
• Installer/contractor availability,
• Product availability,
• Safety (expressed in bus lane visibility and level of skid resistance),
• Short-term installation issues such as odor and fumes,
• Simplicity of implementation (as implementation of some treatments requires specialized training or equipment as well as advance pavement surface preparation), and
• Speed of implementation (as implementation can disrupt transit service, general traffic flow, and driveway access and can also require advance preparation of the pavement surface).

Speed of implementation includes installation time and curing or drying time. Some treatment options also require multiple coats.

The consensus across the case example agencies seems to be that a red-tinting treatment ought to last at least 5 years. An exception to this could be made for pilot projects and projects in corridors where near-term roadway projects would remove the red tinting within 5 years.

The survey results indicate that a number of agencies have moved away from red-paint treatments over time. The primary reason for doing so appears to be the lack of durability of red-paint treatments; the red-paint treatments wear relatively quickly and must be replaced relatively often. A secondary reason for moving away from red-paint treatments appears to be the relatively lengthy installation time required to apply multiple coats of red paint; long installation times can be accompanied by long disruptions to bus service. An advantage of using red paint is that it might be suitable for pilot implementations because it is relatively easy to remove if the agency decides the pilot red-tinted bus lane is not effective or if it wants to modify its design.

Critical influences on the durability of a given red-tinting treatment are surface preparation and the condition of underlying pavement. Driveway density (i.e., more vehicles turning across the bus lane), the types of vehicles allowed in the bus lane, and bus stops also affect the durability of the treatment.

One agency observed that estimates of the life cycle of red-tinting treatments found in literature turned out to be overly conservative for the agencyʼs climate and geography (i.e., the treatments lasted longer than predicted). It acknowledged that this might not be the case in other metro areas.

Some agencies have had inconsistent experiences related to the performance and value of specific red-tinting treatments. These inconsistencies could be the result of differences in climate, geography, material quality, application method, and bus lane usage.

Multiple agencies expressed concerns about the environmental impacts, toxicity, and odors of MMA. One case example metro area moved away from MMA for environmental reasons.

Variations in the shade of red tinting used exist across red-tinted bus lanes in North America. This does not seem to be problematic.

Operations and Enforcement

Some agencies do not have legal authority to enforce bus lane restrictions, so the actions that they can take to reduce bus lane violations may be limited. Also, enforcement technologies and policies are likely to change over time.

Agencies report that, while red-tinted lanes have improved enforcement, they do not completely solve enforcement challenges. That is, red-tinted bus lanes do not eliminate all violations. Improvements like supplemental signage and strategically placed medians and curbs may be needed to reduce violations further.

Agencies with red-tinted bus lanes report that red tinting supports self-enforcement, as does locating bus lanes away from curbs. Self-enforcement of bus lanes is an important goal of bus lane design and operation. Self-enforcement means that the design and features of the bus lane reduce the amount of active enforcement (e.g., law enforcement personnel patrols) needed to ensure that the bus lane operates as desired. Self-enforcement can reduce enforcement costs and improve safety. It can offset the common circumstance of it being difficult to get police or parking enforcement of bus lanes due to limited numbers and competing priorities of enforcement personnel. (Agencies that have influence over police and parking enforcement assignments tend to have more influence over the resources they expend on bus lane enforcement.)

Agencies observe that, where automated enforcement is in use, red tinting makes it easier to detect violations. Red tinting generally reduces the ambiguity about whether a lane violation has occurred, even where automated enforcement is not in use.

Impacts

All but one of the agencies participating in the survey deemed their red-tinted bus lanes effective overall. However, several agencies that have implemented or use red-tinted bus lanes are relatively new to them and are still building experience with different designs, materials, and implementation methods. Many red-tinting projects in North America were completed too recently to have produced quantified impact and maintenance data, and the COVID-19 pandemic limited the ability of some agencies to conduct before-and-after studies.

Lane-usage compliance data seem to be the most readily available data for quantifying impacts of existing red-tinted bus lanes in North America.

Many of the agencies that participated in the survey or case examples were not able to provide quantitative information about the impacts of red tinting specifically, as opposed to the impacts of bus lanes in general. Likewise, many of the agencies were not able to isolate the costs of enforcing and maintaining their red-tinted bus lanes from other enforcement and maintenance costs.

Simplifying enforcement of bus lane restrictions (e.g., with red tinting) could be a strategy for improving bus lane performance.

Agency Guidance

Agencies that have implemented and operate red-tinted bus lanes offer the following suggestions for agencies that are considering implementing or operating red-tinted bus lanes:

• Conduct outreach to and coordination with multiple stakeholders. These stakeholders include partner agencies, riders, law enforcement, local businesses and property owners, and the general public. Use this outreach and coordination to develop partnerships.
• Consider using intermittent or background red-tinting treatments to save costs, unless continuous red-tinting treatments are needed in particular contexts to reduce driver confusion, to maximize the effectiveness of the bus lane, or to emphasize the visibility of the transit service or services that use the bus lane.
• Consider using a double red-tinted bus lane design in the busiest corridors so that through buses can bypass stopped buses. This can also allow space for vehicle loading and separation from right-turning vehicles. (In one case example metro area, there is a red-tinted bus lane segment with a red-tinted bicycle lane adjacent to it.)
• Use durable red-tinting materials.
• Make decisions about red-tinting materials and designs based on their life-cycle costs. The up-front cost of some red-tinting treatments might be higher than the cost of other treatments, but their durability and visibility might be worth the higher cost. Less-expensive products might require maintenance—or replacement—sooner or more frequently.
• To reduce the cost of implementing red-tinted bus lanes, consider coordinating with other agencies and local governments in the region to negotiate price lists for red-tinting materials and pool procurements.
• Snow and parked vehicles can obscure red tinting and other pavement markings, so use signage to help manage bus lane usage.
• Develop a process for requiring utility companies and construction companies to restore red-tinting treatments damaged during their projects or contribute funding toward the repairs. Consider requiring a new warranty for red tinting damaged or removed by utilities.
• Allowing emergency vehicles to use red-tinted lanes can be a significant selling point to get local municipalities on board with a red-tinting project. Another incentive is upgrading local signal systems as part of transit priority projects.
• Consider that, as physical infrastructure, red-tinted bus lanes can demonstrate to the public that transit is being prioritized.

Future Research Needs

Potential topics for future research about red-tinted bus lanes are discussed in the following:

• Collection of red-tinting treatment life-cycle data that reflect different climates, different operating environments (e.g., level of traffic), different materials, different application methods, and the effect of underlying pavement condition would be of value to agencies that are considering implementing red-tinted bus lanes or modifying their current approach to implementing them. Such data would help agencies select and implement the treatments that are most effective for their circumstances. Currently available data do not necessarily represent all application contexts; for example, some agencies have reported that specific treatments have lasted longer in their metro area than predicted by manufacturer specifications and the literature. If field data are not obtainable, laboratory testing may be needed to develop some of the data for this effort.
• Quantified performance data (including skid resistance and rate of wear) for different climates, operating environments, application methods, and underlying pavement conditions would be useful for agencies that are considering implementing red-tinted bus lanes or modifying

• their current approach to implementing them. Current reporting on these topics reveals some inconsistencies in different metro areasʼ experiences and expectations.
• Some agencies have expressed concerns about the environmental and health impacts of different red-tinting treatments. Research could explore these impacts as they pertain to manufacture, installation, usage, maintenance, and removal of red-tinting treatments. Research could also document how agencies are managing potential health risks to personnel involved in installing, maintaining, and removing red-tinting treatments.
• Research could document and evaluate methods that are available for discouraging illegal vehicle turns from or across a bus lane (e.g., use of curbs or delineators) and that might supplement red tinting. This research should consider contraflow and bidirectional bus lanes as well as more-conventional bus lanes.
• Research could develop guidelines for maximizing the extent to which a bus lane is self-enforcing. This research could cover red-tinted bus lanes as well as bus lane placement (curbside, floating, or center-running), signage (content, design, and location), and the role of automated enforcement. The research should account for whether a bus lane is a full-time bus lane or a part-time bus lane.
• Research could document and evaluate methods for accommodating legal vehicle movements in and out of bus lanes (e.g., use of broken-pattern red tinting) and for managing other conflict points.
• Documentation of strategies that have been effective in providing information about red-tinted bus lanes to the public and other stakeholders might be of value to agencies. The research could cover acclimating tourists and other visitors to navigating red-tinted bus lanes. It could discuss data needs and how red tinting has been included in state-level driver education materials (including driver handbooks and driver education courses). It could also attempt to draw conclusions about whether efforts to achieve consistency in design across a region, state, province, and so forth have benefits.
• Research could document and evaluate strategies that agencies have used to make installation and maintenance of red-tinting treatments cheaper or more cost-effective. Different partial-width red-tinting designs and different intermittent red-tinting designs could be part of this research. (The research could also consider challenges associated with the sizing of preformed thermoplastic panels.) The research could analyze the impacts of the lower-cost options on enforcement, safety, and transit service performance and develop guidelines for effective use of such options.
• Documentation of when and how bicyclists are accommodated in red-tinted bus lanes might be of value to agencies. The research could include the development of guidelines based on best practices.
• Research could document the criteria and guidelines that agencies are using for signing and installing supplemental pavement markings in red-tinted bus lanes. The research could document impacts on crash rates and transit performance.
• Research could document the conditions under which agencies choose to remove red tinting from a bus lane, bus stop, or queue jump lane (e.g., maintenance costs or a conversion from a full-time bus lane to a part-time bus lane).
• International experience in the use of red tinting for transit could be documented. Such research might result in recommendations for changes to North American practice.
• Additional research questions asked by the agencies involved in this study are the following:
  • To what extent do fines for violating red-tinted bus lanes fund bus lane maintenance?
  • Does red tinting create side friction that has a traffic-calming effect?
  • Are red-tinted bus lanes more or less effective in suburban areas than in urban areas? Is there a connection between congestion or density and the need for or value of red tinting?