Integrated Corridor Management, Transit, and Mobility on Demand
INTEGRATED CORRIDOR MANAGEMENT AND PUBLIC TRANSIT
PUBLIC TRANSPORTATION STAKEHOLDERS
Institutional integration involves coordination and collaboration between various agencies and stakeholder groups in support of integrated corridor management (ICM), including distributing specific operational responsibilities and sharing control functions in a manner that transcends institutional boundaries. Understanding who public transportation stakeholders are is the first step in identifying the appropriate participants to engage in ICM.
Public transportation includes government-run passenger services for shared use by the general public. An ICM corridor might contain multiple types of transit services and provider agencies, all of which should be included in initial planning discussions. Public transit services that may exist on an ICM corridor include:
When engaging transit stakeholders in an ICM project, it is important to recruit executive level support, as this will trickle down to the management and engineering levels. There should also be a day-to-day contact from each transit agency for technical issues and coordination meetings.
PUBLIC TRANSPORTATION TRENDS
Public transportation use in the United States is growing. According to a study by the American Public Transportation Association (APTA), public transportation use in 2013 was the highest it has been in 57 years. From 1995 to 2013, "public transportation ridership grew 37.2 percent, almost double the amount of population growth."3 This trend is likely to continue as attitudes about transportation are shifting. Young Americans (16 to 34-year-olds) are driving less; according to the National Household Travel Survey, the annual number of vehicle miles traveled by young people decreased 23 percent from 2001 to 2009. During the same timeframe, the number of passenger-miles traveled on public transportation by this age group increased 40 percent per capita.4 This generation is also factoring proximity to public transit into their housing decisions, driving urbanization and driving the demand for other situational mobility choices such as bike share, ride share. Together, these factors point to the continued growth in demand for and use of public transportation.
Meeting this demand may prove challenging for public transit agencies due to a lack of financial resources. Fare revenue typically does not cover agencies' operating costs, which rely significantly on government subsidies. This means that many agencies struggle to maintain their existing systems, much less invest in new technologies and upgrades.
The emphasis on public transit in Federal legislation reinforces its importance in the Nation's transportation system. As such, regions pursuing initiatives such as ICM should increasingly look for innovative ways to incorporate transit or other mobility services and models into their approaches.
BENEFITS OF INTEGRATION
The integration of public transportation and other mobility services into ICM planning and implementation offers a number of potential benefits to operators and users of the transport system:
The benefits noted above can support transit agencies' goals and objectives (see table below). In order to gain buy-in and support from public transit agencies, ICM project leaders should be prepared to effectively articulate how ICM could help achieve these transit-specific goals (i.e., what's in it for them?).
STRATEGIES FOR INTEGRATED CORRIDOR MANAGEMENT INTEGRATION
There are numerous strategies that agencies implementing ICM can consider to further integrate public transit into corridor operations. These strategies can both improve transit operations and enhance overall corridor performance and user experience by optimizing throughput. While not all of these strategies will be appropriate for every corridor implementing ICM, they offer a range of strategies which agencies can consider before narrowing down to those approaches that work best based on resources available and corridor travel patterns.
Transit Priority Treatments
Figure 4. Photo. Example of a transit/high-occupancy vehicle priority on-ramp in California.
Source: Federal Highway Administration.
One strategy to incorporate transit into ICM is transit priority or preferential treatments, which can enhance the efficiency of transit operations, reduce delays and congestion, and improve overall mobility and user satisfaction. Transit signal priority (TSP) and dedicated transit vehicle facilities are the most common preferential treatments for transit in an ICM environment.
Transit Signal Priority
TSP strategies adjust signal timing at intersections to better accommodate transit vehicles. Typically, a bus approaching a traffic signal will request priority. This request is often transmitted directly from an approaching bus to a traffic signal, but may also be originated by a centralized transit priority management system. When a request is received, the traffic signal controller applies logical rules to decide whether or not to provide priority to the bus. These rules typically include consideration of whether the bus is behind schedule, the length of time since the last priority was awarded to a bus, the state of the traffic signals along the route, and the time of day. In most cases, the form of priority given is to extend an existing green phase to serve the bus or to shorten other phases to start the next green phase for the bus earlier.
In simple TSP systems, each signal controller operates independently. It detects the bus directly and does not receive priority requests from any external source. It makes a decision about providing priority without reference to any external system or consideration of the state of any other signal controller. In more complex systems, a central priority management system may determine when to request priority at various intersections and employ more complex rules that include feedback from the traffic signal system. This type of system could potentially be integrated into larger ICM system.
Dedicated Transit Vehicle Facilities
A second common form of transit priority treatments include dedicated transit vehicle facilities, such as exclusive busways and high-occupancy vehicle (HOV) lanes. Because of their scale, such facilities would generally be implemented as stand-alone projects; however, a number of other smaller-scale treatments and strategies could be implemented as part of an ICM project.
For example, on arterials where transit vehicles generally operate within a shared lane environment, queue jump lanes may be used at isolated delay points. The queue jump lane may take the form of a separate lane developed for buses only, or may involve allowing buses to use a right-turn lane as a through lane. A separate lane is essential where there are heavy right turns that move on special phases. If an existing right-turn lane is used, the queue jump operation may be limited to peak periods only. In either case, the queue jump lane should be of sufficient length to allow the buses to bypass the general traffic queue at the intersection most of the time. On a roadway with existing shoulders, a queue jump or bypass lane treatment can be developed assuming shoulder width (10 feet minimum) and pavement design can accommodate bus traffic.
If there is no receiving lane on the downstream side of the intersection, a separate, short bus signal phase (3 to 4 seconds) would need to be provided that gives the bus an early green to move into the through lane ahead of general traffic. Typically, green time for the parallel general traffic movement is reduced to accommodate the special bus signal phase. To detect buses in the queue jump lane, an in-pavement loop sensor in the queue jump lane on the near side of the intersection (just short of the stop bar or crosswalk) or video detection can be used. In cases where there is a downstream receiving lane, the bus would not have a separate signal phase but would continue through the intersection into a far-side stop before pulling back into general traffic.
On freeways, an example of a smaller-scale transit priority treatment is a transit/HOV priority lane on a metered on-ramp. These priority lanes can be unmetered, but more typically are metered to provide preferential treatment to transit vehicles/HOVs (e.g. serve vehicles in the priority lane first or more frequently). In the latter case, this priority treatment needs to be incorporated into the ramp metering algorithm.
Bus queue jump lanes are relatively uncommon in the United States. While on-ramp transit/HOV priority lanes are common in some areas of the country such as California, they have not been widely implemented in most areas. Within the context of ICM and transit integration, it may be possible to define the applicable priority rules, construct the dedicated facilities, and implement the necessary technology (e.g. transit vehicle detection or location systems, signal or meter hardware and software upgrades, etc.) as part of an ICM project.
Shared Communication Infrastructure
The transmission of data and information between facilities, in-field equipment, and vehicles is vital to effective monitoring and management of every transportation system. For roadways, this may include the flow of data from detectors and other surveillance equipment to a central operating center, and the flow of operating commands from the operations center to electronic signs and controllers. On the transit side, there is the flow of location and operating status information from vehicles to an operations center, and the flow of schedule status information to electronic signs at stops and stations. While many agencies are shifting to wireless systems, communication networks often still involve significant wireline infrastructure involving conduit, pullboxes, cables and end equipment. Often times, individual agencies implement their own networks or infrastructure, creating redundancies, overlaps, and cost inefficiencies.
Because most ICM and system management projects involve implementation of a supporting communication network, the integration of transit into an ICM project provides the opportunity to incorporate transit agency needs into the communication network and infrastructure. Coordinated implementation can help reduce overall costs, support compatibility between equipment, and minimize disruption caused by infrastructure construction. It also facilitates information sharing and coordination (see "Interagency Information Sharing and Coordination" below).
Information Sharing and Communication
In addition to supporting individual agency decision-making, information sharing can facilitate coordination between different modal agencies, between transit agencies, and between agencies and travelers. Having common and comprehensive information about current transportation system conditions can also lead to consistent and compatible operating decisions across the various system managers.
Roadway-Transit Information Sharing and Communication
A critical element in the management of transportation facilities and services is knowledge of current conditions and operations. To this end, roadway managers often deploy monitoring devices such as roadway detectors and video cameras to track traffic flows and speeds. Similarly, transit operators use AVL systems and other means to monitor the movement and status of their vehicles. However, this information is often not shared between roadway managers and transit operators.
The integration of transit into an ICM system requires the implementation of protocols and systems to share pertinent information and data. As noted above, this can be greatly facilitated by the implementation of shared communication infrastructure. The ICM project development process can also provide a forum for developing or enhancing interagency communication and coordination. In the case of a severe or major incident, interagency coordination in a region may already occur through an emergency operations center; however, this is limited in application. Under an ICM approach, information is shared more routinely. This provides roadway and transit managers with a more complete understanding of system conditions, which supports more informed and coordinated operations and management decisions.
For example, transit system data can not only provide roadway managers with additional information about traffic conditions (see "Use of Transit Vehicles as Probes" below), but can also alert them to transit-related incidents that impact traffic operations, such as a bus breakdown that blocks a travel lane or a rail line breakdown that causes a shift in demand from transit to auto travel. This information may then be used to adjust roadway management and control strategies accordingly. From the transit operators' perspective, roadway or traffic data could be used to re-route service around congested areas or make other service adjustments in response to major roadway traffic incidents that may impact (increase) transit service demand in a corridor.
Transit-Transit Information Sharing and Communication
In addition to improving communication between transit and roadway agencies, ICM provides an opportunity to enhance coordination between public transportation operators, transit agencies, and metropolitan planning organizations (MPO) in regions with multiple providers. This could include sharing information about system status and delays to improve transfer timing, or possibly sharing data, virtual operations, assets or dispatch centers.
Coordinated services allow travelers a seamless transfer between modes and providers. One potential strategy to better integrate transit services is through joint fare payment systems, which can be rolled into a broader ICM project. In regions with multiple transit providers, this would allow users to easily shift between transit services without having to purchase and keep track of individual fare cards. For example, in Chicago, Chicago Transit Authority (CTA) owns Ventra, which is "one card and one system that does everything."5 Users can pay fare for CTA or Pace – the two major transit providers in Chicago – using a Ventra card, tickets, a contactless credit or debit card issued by their bank, or a smartphone. A Ventra smartphone app is also under development, which will incorporate information for transit trip planning.
Another potential model for transit agency coordination is the U.S. Department of Transportation's Mobility Services for All Americans (MSAA) initiative. This program aims "to improve transportation services and simplify access to employment, healthcare, education and other community activities"6 by improving coordination between transportation providers for older adults, people with disabilities, and the economically disadvantaged. This is achieved through development of a virtual or physical travel management coordination center (TMCC) that networks all parties together and uses proven ITS technologies to provide:7
Using the TMCC, agencies are able to schedule trips more efficiently and better match capacity to trip requests. In an ICM corridor, this approach could be considered on a daily basis or to address traveler needs when there is an incident on a particular transit route or line.
Transit-Traveler Information Sharing and Communication
Figure 5. Photo. Comparative freeway and transit travel times on a dynamic message sign in California.
Source: A. Mortazavi et al., Travel Times on Changeable Message Signs Volume II – Evaluation of Transit Signs, UCB-ITS- CWP-2009-2 (CCIT, 2009)
In today's connected world, travelers have many sources for traffic and transit information, such as various public agency internet and phone systems (e.g. 511); roadside dynamic message signs (DMS); arrival/departure signage at transit stops and stations; television and radio reports; third-party services (e.g., websites and smartphone apps such as Inrix and Waze); and newer in-vehicle navigation systems. For traffic conditions, information typically includes congestion levels, travel times, and incidents. On the transit side, information includes schedules, next arrival, and service disruptions.
These information sources have a number of common shortcomings. First, they are often mode- specific and most often focused on traffic conditions. Second, transit information is typically static or schedule-based, not real-time. When real-time transit information is provided, oftentimes it is only to report a significant incident or delay.
ICM-transit integration can provide the opportunity to incorporate real-time or predictive transit information into traffic information and to better disseminate this information in a coordinated manner. This equips travelers with the ability to make informed decisions about travel options, leading to more efficient utilization of corridor assets.
Diverting single occupant vehicle drivers to transit or other modes can be an effective way of relieving congestion during traffic incidents on the roadway. However, convincing drivers to shift to transit can be challenging unless they are familiar with and comfortable switching between modes. To encourage mode shift, agencies can provide incentives to try transit, such as discounts for low-income riders and frequent user rewards. These incentives could potentially be offered during the early stages of an ICM deployment so that travelers become more aware of the transit options available to them.
It could also be part of an ICM approach to reduce or eliminate transit fares during major incidents based upon predefined conditions of traffic delays (i.e., during incidents of a certain level of severity). In combination with temporary park-and-ride lots or transit "bridges" to access primary line-haul transit (see box on p. 29), this can be a very cost-effective strategy for diverting travelers. Use of an automated fare payment system facilitates easy reduction or refunding of transit fares and transfer of funds among partner agencies.
Use of Transit Vehicles as Probes
Real-time information on current conditions and operations is a critical element in transportation management. To this end, ICM projects typically include the implementation of monitoring devices such as roadway detectors and video cameras where they are not already installed. The integration of transit into an ICM system can provide additional monitoring capabilities.
In cases where transit vehicles are equipped with an AVL system, speed and travel time information can be shared with roadway managers. This may be most appropriate for long-haul or express services where the transit vehicles have few or no stops, and thus their travel speeds or times are generally reflective of other vehicles on the roadway. However, even data from local transit services may be useful where post-processing procedures recognize and account for scheduled stops when computing travel times. In either case, monitoring programs may be set up to identify when travel speeds or times fall outside acceptable parameters or excessive delay occurs at non-stop locations.
Another possibility for gathering real-time data is video feeds from cameras installed on transit vehicles. While such cameras are typically used to monitor activities within transit vehicles, there is a growing trend of installing front-facing cameras to view conditions ahead. This "driver's view" has the advantage of covering the entire route and can supplement roadway video monitoring systems.
A third opportunity is to use the transit vehicle driver as another "set of eyes" in the field. Drivers could report on incidents through their dispatchers or directly to the applicable roadway managers. Again, this would be a supplement to other video monitoring systems, with the possible advantage that drivers could provide additional details from the field. This concept would be facilitated by the increased level of agency coordination and communication arising from the joint implementation of an ICM project. Recognizing that most transit agencies may be hesitant to add to the responsibilities of their drivers, this may only be applied to the reporting of significant incidents.
A fourth opportunity involves using bus sensors, particularly the telematics, to survey the physical condition of the road and system behaviors. For example, a record of the vertical accelerometer can be used to identify the location of potholes. A record of braking force can be used to map common bottlenecks and the propagation of their congestion as well as be used as a criteria in a pavement management plan (a heavy vehicle stopping every day at the same place will probably lead to premature pavement buckling.)
Challenges to Integration
Although strategies for integrating transit into corridor operations show great potential, there are still challenges associated with this process. While none of the challenges described below are insurmountable, ICM teams should take them into consideration to be sure that they are addressed during the planning and development stages of the ICM project.
Resistance to Roadway-Transit Coordination
Most transit agencies operate independently of highway departments and other modes. Federal funding sources are also typically separated into modal "silos" (Urban Mass Transit Act/Federal Transit Administration and Federal Highway Administration, respectively). In more recent years, the USDOT has adopted a "One DOT" policy as a multimodal approach; however, it takes time for industry to react, and organizational inertia drives transportation agencies to continue to operate in their familiar way of doing business.
In many cases, there is a history of less than amicable relationships between highway and transit interests, which can lead to a mutual lack of trust. With ICM, transit providers may perceive that they are being asked to hand over control of transit services to roadway agencies. They may fear that the roadway operators will overreact and commandeer transit assets in response to relatively minor incidents on the network.
In addition, some agencies may fear jeopardizing their transit operations by participating in ICM. Diverting drivers from the freeway to transit as part of an ICM response could be viewed as disruptive to regular transit riders. Why should they suffer delays and overcrowding on "their" buses or trains? As loyal transit riders, they may be feel they are being penalized when the roadway experiences an incident. Also, fixed guideway transit systems (rail and bus) can benefit from traffic delays on the primary freeway in a corridor; with exclusive rights-of-way, transit can deliver more reliable travel times, whereas highway travel times can vary greatly. Recent research has shown that travel time reliability is of greater importance to commuters than travel speeds. Some transit operators may worry that their reputation for reliability will be jeopardized if they change their operations to benefit overall corridor performance.
It is understandable that transit agencies may question "what's in it for them" when considering ICM, but careful communication in a forum that allows transit agencies to express their concerns may help mitigate this response. The challenge lies in effectively conveying the benefits of ICM to the traveling public as a whole.
Lack of Resources
Fare box revenue covers only a portion of total costs for most transit agencies. Many agencies struggle to provide basic services and may not have resources to take advantage of new systems and other changes in operations. Even if an ICM program were to provide capital costs, transit agencies may not have staff resources to actively monitor additional information or to maintain any new equipment. In addition, transit services may not have spare capacity at peak periods when ICM scenarios commonly would kick in, and they may not have the budget to make a major capital investment to add capacity. In these situations, ICM implementers will need to think carefully about under which circumstances they are able to use transit, as well as potential strategies to increase transit capacity without adding significant new infrastructure.
Transit providers may also feel that they have little or no flexibility in adjusting service to accommodate ICM applications. During peak periods, transit agency assets (bus and rail capacity, park and ride lots, drivers) may be in full use already, especially in congested urban areas. Rail lines in many metro areas are packed at peak commuting periods, as are buses during special events and incidents when ICM scenarios are most likely. In addition, providers may not have the ability to re-route their buses, as they are required to hit every stop. Negative impacts on bus operations may affect lower-income residents along the corridor in favor of more affluent travelers from the suburbs (particularly for auto-centric metropolitan areas in the Southern and Western United States), which could trigger environmental justice concerns.
Competition among Transit Providers
Transit agencies may not be interested in coordinating services, because multiple providers within a corridor may see themselves as serving "different markets." They may be focused on their operations only, serving their tax district with the services that they are dedicated to provide. On the same corridor, one agency may provide a pass-through, commuter-based service, while another agency may serve a more local community. For example, Bay Area Rapid Transit (BART) and San Francisco Muni operate heavy rail, light rail, trolley, and bus service all along essentially the same corridor within San Francisco city limits, but they serve different commuter and local needs. Agencies may also view each other as competitors, and to may be territorial with regard to their geographic "turf." There can be very strict adherence to crossing county lines or other boundaries that inhibit full corridor efficiency.
Despite the fact that agencies may see themselves as having different interests, their customers – passengers – often transfer between multiple public transportation services (i.e., take one bus route for part of their trip, then transfer to another bus or to rail). Therefore, it is important for agencies to realize that they share the end goal of supporting common customer needs, and the best way to do that is to provide as coordinated services as possible in order to facilitate seamless travel along the corridor. In Florida, Dade and Broward Counties have recently come together to provide "one-seat" service along I-95, whereas in the past, commuters would need to transfer buses in the middle of the corridor.
Another obstacle to implementing a number of the transit-specific ICM strategies is a potential conflict with the objectives of roadway managers and the needs of other transportation system users. For example, while implementing TSP can reduce delays for transit vehicles and passengers, as well as other vehicles traveling in the same direction, it can result in added delay to vehicles making conflicting movements. This may oppose the roadway system manager's objective to minimize vehicular delay and maximize vehicular throughput, rather than person delay and throughput.
Likewise, implementing a transit priority facility, such as a queue jump lane at an intersection or a transit or HOV priority lane on an on-ramp, may mean taking right-of-way that could be used for other purposes, such as a general-purpose traffic lane, parking, or a bicycle lane. A common argument against shoulder use by transit vehicles is that this space is needed for vehicles to pull over in case of a breakdown or incident.
Overcoming the challenge of conflicting objectives begins with acknowledging the different interests and needs of corridor agencies, while recognizing the importance of a balanced, multimodal transportation system. This should be followed by analysis to determine the actual benefits and impacts of transit-based strategies. For example, in the case of TSP, analysis may show that priority requests are so infrequent that the impact to conflicting movements is limited and even offset by the reduced delay for concurrent movements. Lastly, measures to address any impacts should be explored. For example, when allowing shoulder use by buses, monitoring systems can be implemented to detect when the shoulder is occupied by another vehicle and alert the bus driver to use the adjacent travel lane.
Shared Use/Access Restrictions
While integrated strategies can lead to cost-savings and operational benefits, they can raise institutional issues regarding access to and maintenance of equipment. Most TSP-related functionality is located within traffic signal controllers, which are typically managed by local departments of transportation. If a TSP operation fails or needs fine-tuning, agencies will need to coordinate to fix the issue. The roadway agency may not want to allow the transit agency to access the controller, and the transit agency may not trust that the roadway agency will fix the issue in a timely fashion, especially if the signal is otherwise operating fine. Similarly, in the case of a shared communication network, agencies will need to determine who is responsible for maintenance an establish protocols to ensure that disruptions are repaired promptly, without impacts to any mode's operations. These and related issues need to be addressed in the planning stages of an ICM project. This includes clearly defining roles and responsibilities, as well as performance requirements and contingency plans where appropriate.
ICM implementers will also need to account for practical equipment limitations when considering strategies. For example, although one strategy to encourage mode shift may be to display transit travel times on DMS, the Manual on Uniform Traffic Control Devices (MUTCD) limits the number of signs and the quantity of information that can displayed for safety and traffic operations reasons. In addition, agencies may need to update their equipment to apply certain strategies; for example, TSP requires more sophisticated signal controllers, which an agency may not have the resources to purchase and install. As part of the ICM planning process, implementers should be aware of these constraints and discuss opportunities for funding technology upgrades.
Counterproductive Traveler Information
Providing real-time traveler information is central to an ICM approach, but in some cases, this can be counterproductive to transit ridership. Many riders choose to take transit for reliability. Transit services that have exclusive (or priority) right-of-way are less prone to disruptions due to unpredictable events such as incidents than are freeway commutes. However, transit riders may overestimate their time savings or make their mode choice based upon the worst-case incident that they have experienced on the freeway. With real-time travel times provided for transit and roadway options, transit riders may realize that driving is typically a quicker option than transit and switch modes. Given this, some transit providers may prefer to only provide transit-specific information, such as "next bus," park and ride availability, directions to stations, and route maps, rather than comparative travel times across modes.
3 American Public Transportation Association, "Public Transportation Use is Growing – Here Are the Facts" web page. Available at: http://www.apta.com/mediacenter/ptbenefits/Pages/Public-Transportation-Use-is-Growing-.aspx. [ Return to footnote 3. ]
4 B. Davis, T. Dutzik, and P. Baxandall, Transportation and the New Generation: Why Young People Are Driving Less and What It Means for Transportation Policy, (The Frontier Group, April 2012). Available at: http://www.frontiergroup.org/reports/fg/transportation-and-new-generation. [ Return to footnote 4. ]
6 USDOT, Intelligent Transportation Systems Joint Program Office, "Success Stories: Mobility Services for All Americans (MSAA)" web page. Available at: http://www.its.dot.gov/msaa/. [ Return to footnote 6. ]
7 USDOT, Intelligent Transportation Systems Joint Program Office, "Success Stories: Mobility Services for All Americans (MSAA)" web page. Available at: http://www.its.dot.gov/msaa/. [ Return to footnote 7. ]
United States Department of Transportation - Federal Highway Administration