Strengthening Linkages between Transportation Demand Management and Traffic Management
Context 5. Using High-Occupancy Toll and Priority Treatments for Transit Service Enhancements
Providing more reliable travel times during congested periods has become a central goal for the performance of key corridors and regional highway systems in most urban areas of the United States. Predictability in how long it will take to travel from, say, home to work or to school is of paramount interest to the traveling public. Several urban areas are providing a reliable alternative to congested lanes in the form of high-occupancy toll (HOT) lanes and dynamic priority lanes for buses (figure 17). These special lanes are a dynamic traffic management strategy that also take advantage of demand management approaches.
The three case studies under this context provide examples of how priced and other special lanes and the offer of enhanced transit and ridesharing services can be implemented to realize the benefits of this linkage.
HOT lanes provide excess capacity in carpool lanes to drive-alone travelers while maintaining free-flowing condition (generally set at level of service C or D). Single-occupancy vehicles (SOV) that wish to use the HOT lane are able to pay a variable-fee toll, which is adjusted in response to demand of the lane at a given time. The toll increases as the lane fills up and the increased toll reduces demand of the lane, allowing the lane to maintain free flow conditions.
Figure 17. Illustration. A Los Angeles County Metropolitan Transportation Authority bus traveling in a bus-only lane.(39)
(Source: Los Angeles County Metropolitan Transportation Authority).
For these alternatives to be most effective, it is important to offer travelers both a priced alternative (toll) for single-occupant travelers and free or discounted use of the special lanes for high-occupancy and transit vehicles. Public outreach to help travelers understand the options is also needed.
Special bus-only lanes allow buses to bypass congestion by operating transit priority lanes at bottlenecks. In the case of the Chicago Pace bus-on-shoulder case study, some lanes dynamically use the breakdown lane or shoulder during peak periods to improve bus travel times and schedule adherence. Special bus-only lanes in Manhattan and the Lincoln Tunnel have operated for many years.
Use of priority treatments and transit use in HOT lanes provides a clear opportunity to emphasize person throughput on a facility. As highlighted in the following case studies, early consideration of transit and high-occupancy vehicle needs in managed lanes can provide improved choices to travelers across multiple modes.
Case 10. MOPAC Improvement Project (MOPAC Express Lanes)
Reliable toll, bus, and vanpool options in a congested Austin corridor
Texas State Highway Loop 1—also known as Mopac (after the Missouri Pacific Railroad that runs down the center of the facility)—is one of the most important transportation arteries in Austin (figure 18). Serving as a key central route to downtown, Mopac is a primary north/south alternate route for I-35 and carries more than 180,000 vehicles each day, with 2030 volumes projected to be more than 320,000 vehicles. The congested corridor experiences unreliable travel times during the peak hours.
Figure 18. Photo. Vehicles traveling on the northbound Mopac Express Lane and general-purpose lanes.(40)
(Source: Central Texas Regional Mobility Authority).
The environmental study launched in 2010 to consider options for improving mobility in the corridor identified express lanes in the median with variable pricing as the preferred alternative for the corridor. The Texas Department of Transportation and the Central Texas Regional Mobility Authority signed a financial assistance agreement to support the development and construction of the Mopac Improvement Project in Travis County.
The Mopac Express Lanes, one lane in each direction, opened in 2017 and require all passenger vehicles to pay a toll. However, the facility exempts travelers in buses and vanpools operated by transit agencies from paying the toll. At this time, an overall evaluation of the project has yet to be completed. An analysis conducted in the first full month both express lanes were opened (October 2017) found that 61 percent of vehicles only used the express lane one time that month, demonstrating that most vehicles use the lane only when they need it most.(41) This same report noted that vehicles in the northbound Express Lane traveled an average 27 mph faster than vehicles traveling in the general-purpose lane.
Strategies Providing Mode Choice
The Express Lanes provide toll-exempt priority service to public transit buses and registered vanpools. To improve bus service, the Capital Metropolitan Transportation Authority, Austin's regional public transportation provider, added two new express routes (17 peak-period trips) and adjusted and increased frequency on two existing routes (from 21 to 60 trips per day) to use the special lanes. Additionally, bicycle and pedestrian improvements were made in the corridor including 4 miles of shared-use path, a bridge over the railroad tracks, four miles of sidewalks, Americans with Disabilities Act enhancements, and bike lane improvements at 13 cross streets.
Strategies Providing Lane Choice
The variable pricing component of the Express Lanes project provides drivers with an uncongested and reliable alternative to the more congested general-purpose lanes. The system use 17 high-definition cameras and vehicle detectors to monitor traffic levels in the Express Lane, adjust the toll rates, and maximize the number of vehicles that can be carried in the Express Lanes at a target speed of 45 mph for a reliable, free-flowing trip. When traffic in the Express Lanes is moving slower because demand has been high, the toll rate for vehicles entering the Express Lanes is higher to discourage use. When demand for the Express Lanes reduces, the toll rate decreases.
Noteworthy Outcome
During the first 30 days after opening, drivers traveled an average of 27 mph faster than those in the general-purpose lane during the afternoon rush hour.
Success Supportive of the Integration of Transportation Demand Management and Traffic Management
The addition of considerably more express bus service (new routes and new trips) has increased service by 50 percent. Routes were adjusted to use the Express Lanes for more reliable and faster trip times. Additionally, registered vanpools can use the lanes for free, and carpools can share the cost of the toll for more reliable travel times.
Metro Rapid Demonstration Project—Transit Priority
In response to concerns about slow and unreliable bus service, the Los Angeles Department of Transportation (LADOT) introduced a new service designed to improve transit operating speeds through a system of operating changes and priority bus treatment strategies. These included bus signal priority, level boarding/alighting with low-floor buses, headway rather than timetable-based schedules, fewer stops, far-side intersection location of stations, and joint active management of the service in the field and the Metropolitan Transportation Authority Bus Operations Control Center. Since the initial date of service, the Metro Rapid operation has achieved an overall operating speed improvement of between 20 to 31 percent. Independent research conducted by the City of Los Angeles found that the bus signal priority system accounted for approximately one-third of the speed improvement, while the other elements accounted for the remaining two-thirds of the benefit. LADOT's running time data indicate that the segments with bus signal priority operate faster than the adjacent segments, especially when ridership loads are considered.
Sources Used: Federal Transit Administration.(42)
Case 11. I-110/I-10 Expresslanes High-Occupancy Vehicle Incentives (Los Angeles County)
Giving options to encourage HOV lane use
I-10 and I-110 are two urban freeway facilities serving downtown Los Angeles that each include busway facilities (one built in 1973 and the other in 2009) and are open to vanpools and carpools (one requiring three or more occupants and the other two or more occupants). Both are highly congested, especially during peak commute periods.
To increase the effective capacity of the two facilities, the California Department of Transportation (Caltrans) and Los Angeles County Metropolitan Transportation Authority (LA Metro) received a National Congestion Reduction Demonstration program grant from USDOT to convert these two HOV lanes to HOT lanes (called ExpressLanes) in 2013. The HOT demonstration project allowed SOV commuters to pay a variable-fee toll, ranging from $0.25 to $1.40 per mile, to use the facilities while at the same time improving transit services. HOVs can use the Express Lanes and be exempt from the told during specific times if they meet the occupancy requirement (Figure 19). Drivers can indicate their vehicle's occupancy using a flex toll transponder. A unique feature of the flex toll transponder is a switch with three positions (SOV, two-or-more-person carpool, and the three-or-more-person carpool) that a driver can adjust as needed. In addition to the lane conversion, as part of this program, federal funds were used to purchase 59 new clean-fuel buses, security and lighting improvements at transit stations, new bike lockers, construction of a new transit station, expanded transit signal priority in downtown Los Angeles, and LA Express Park—Los Angeles' new intelligent parking management program that uses sensors to gather parking occupancy data.
Figure 19. Illustration. How carpools, vanpools, and solo drivers can use the ExpressLanes.(43)
(Source: LA Metro).
LA Metro cites the benefits of the ExpressLanes as "More choices for solo drivers, more rewards for carpoolers, more transit services."(44) The ExpressLanes demonstration project was widely viewed as a success for its improved service to transit, carpools, and vanpools. It has continued after the pilot period ended. Over 100 new vanpools were formed in the two corridors during the demonstration period.
Strategies Providing Route Choice
The ExpressLanes provide solo drivers with reliable travel times during peak travel periods along I-110 and I-10 to and from downtown Los Angeles. The ExpressLanes also serve as an alternative to parallel facilities, such as the 710 and 60 freeways.
Strategies Providing Facility or Lane Choice
When the regular lane is congested, the ExpressLanes provide solo drivers with an uncongested lane alternative and reliable travel times along I-110 and I-10 to and from downtown Los Angeles.
Success Supportive of the Integration of Transportation Demand Management and Traffic Management
The ultimate goal of this project was to address congestion through capacity, but this was tackled by bundling SOV traffic management strategy with improving service for transit, carpool, and vanpool modes.
Case 12. I-55 Buses on Shoulder (Chicago Region)
Dynamic coordination of transit and traffic during peak period
I-55 (the Stevenson Expressway) in Illinois serves suburban communities southwest of Chicago and their resultant long-distance commutes (15–25 miles) into downtown Chicago. Commuter rail services are limited. While the expressway is already used by Pace Suburban Bus (the public transit and vanpool provider servicing the Chicago suburbs) commuter express routes, travel times were highly unreliable due to recurring congestion on the Stevenson Expressway. Bus travel times were over one hour and varied by more than 15 minutes.
Figure 20. Photo. Bus traveling on the shoulder.(45)
(Source: Pace Suburban Bus).
To increase the reliability of bus travel times and improve the attractiveness of public transit, a partnership between Pace and the Illinois Department of Transportation (IDOT) implemented a pilot program in 2011 to test the use of the shoulder for buses during congested conditions. Costing less than $1 million, the Buses on Shoulder pilot (planned by the regional transit authority) was promoted as a cheaper and more cost-effective alternative to constructing a new bus-only lane or rail line. The State passed legislation that allowed buses to use the shoulder and dictated the conditions for the use.
The pilot program involved two Pace commuter express bus routes. Buses could use the inside (left) shoulder when travel speeds in the main lanes dropped below 35 mph (figure 20). IDOT added signs on the shoulder indicating Pace transit vehicles may use the shoulder, and the buses themselves have external signage stating "Authorized to Use the Shoulder." IDOT's Operations and Communications Center closely coordinates with the Pace bus operations center to monitor conditions and use of the lane. Coordination on traffic and bus operations occurred prior to the pilot but were brought to a new dynamic level as a result of the use of the shoulder on I-55.
As a result of the success of the pilot, service has been expanded to include three more Buses on Shoulder routes, the State legislature enabled buses on the shoulder for all expressways and tollways in the region, and a new flex lane for Pace buses is operating on the shoulder of the Illinois Tollway (I-90) as part of an active traffic management scheme.
Strategies Providing Mode Choice
Initially, bus service levels were not changed, but improved transit travel time reliability made this commuting choice more attractive. Buses traveling faster than cars in a dedicated lane likely made this option appear more attractive.
Strategies Providing Facility or Lane Choice
The use of the left shoulder, on a dynamic basis (contingent on congestion levels and travel speeds), allowed Pace commuter express buses to improve their operating speed relative to main lane traffic and improve bus schedule reliability. This strategy enabled transit, which traditionally does not have the option to find a faster route (especially in a non-toll road environment), to have a choice to use a lane that would enable the vehicle to travel at a higher speed.
Noteworthy Outcome
Bus ridership increased six-fold on Pace routes, and transit schedule reliability improved from less than 70 percent to more than 90 percent.
Success Supportive of the Integration of Transportation Demand Management and Traffic Management
A relatively simple traffic management technique (buses on the shoulder) made transit a more attractive alternative, inducing a mode shift and fostering enhanced cooperation between roadway (IDOT) and transit (Pace) operators. The Stevenson Expressway Buses on Shoulder pilot has resulted in a six-fold increase in bus ridership on Pace routes and an improvement in transit schedule reliability from less than 70 percent to more than 90 percent.
