Office of Operations
21st Century Operations Using 21st Century Technologies


The purpose of this chapter is to identify lessons learned from three case studies of HOV to HOT conversion projects:

  • I-15 Express Lanes (San Diego, CA)
  • MnPass (Minneapolis, MN)
  • I-25 Express Lanes (Denver, CO)

Figure 5-1: Location of Hot Lane Case Studies

Graphic. Figure 5-1. Location of Hot Lane Case Studies.

These three case studies were chosen to supplement the growing body of research exploring the relationship between program objectives, system design, concept of operations, toll collection strategies and operational requirements. Each case studies attempts to identify outcomes (intended and unintended) based on specific operational choices and address key lessons learned, or best practices in the planning, design and implementation.

5.1 Data Collection Approach

Information available form published data for each of the operational case study sites was integrated with focused interviews conducted at the project site, when possible. To provide a common baseline, or starting point for the interviews, a focused interview guide was developed to facilitate in-depth probing of key project development issues and challenges in four main areas, including:

  • Public Outreach and Communications
  • Planning and Policy
  • System Design Procurement
  • Management & Operations

5.2 Focused Interviews

The three systems were specifically chosen for the case studies because they were converted from HOV lanes to HOT lanes or were in the planning process for expanding existing facilities to HOT lanes and had been operational for at least one year.

On-site interviews with the management and operations staff were conducted at the I-15 Express Lanes in San Diego, California and MnPass in Minneapolis, Minnesota. For I-25 Express Lanes in Denver, Colorado, remote discussions were conducted with key management staff. As mentioned previously, the interviews were designed to address specific issues and challenges faced at each stage of project development to include public outreach, planning, design, implementation and operations. Tables 5-1 and 5-2 provide a comparative summary comparison of the three operational case sites key site properties and operational characteristics.

Table 5-1: List of Desirable Elements
Site Length Type Lane # Access Points Toll Points GP - ML Separation
I-394 11 mi 8 mi - SLn
3 mi - 2 Ln Rev.
Multiple - SL
Rev. Entry / Exit
7 WB 6 EB Double White, Rev. with Barrier
I-15 8 mi 2 Ln Rev. Entry / Exit 1 Rev. with Barrier
12 mi 2 Ln HOT Multiple Multiple Double Yellow, Movable Barrier
I-25 10 mi 3 mi SLn
7 mi 2 Ln Rev.
Entry / Exit 1 Double White, Rev. with Barrier

Note: I-15 HOT expansion includes four lanes (two in each direction), with movable barrier separation in southern section and double yellow strip separation in northern section between HOT and general use lanes.

Table 5-2: Operational Characteristics
Site Open Type Hours of Ops Authorized Users Tag Requirement
I-394 2005 SL HOT
AM Peak
PM Peak
Non-Peak Closed
2 axle, HOV+2 Buses Only SOV
1996 R2L HOT AM Peak
PM Peak
Non-Peak Closed
2 axle, HOV+2 Buses Only SOV
I-25 2006 SL HOT
AM Peak
PM Peak
Non-Peak Closed
Trucks, HOV+2 Buses Only SOV

The following sections briefly summarize the key findings from the focused interviews for each of the operational sites, SANDAG’s I-15 Express Lanes, MnDOT’s MnPass, and CDOT’s I-25 Express Lanes.

5.3 San Diego, CA I-15 Express Lanes

The I-15 Express Lanes (FasTrak) opened in January 1997 as a three year value pricing demonstration that has been operational since transitioning from HOV only to HOT Express Lanes in January 2000. The original facility was an 8-mile, two lane, reversible HOV facility. With over 10 years of operational experience, SANDAG will expand the existing reversible facility to four bi-directional HOT lanes with multiple intermediate access locations of over 20 miles in length.

5.3.1 Project Objectives

  • Provide additional highway capacity on what had been a largely underutilized HOV facility.
  • Provide better management and utilization of the HOV lanes.
  • Achieve and maintain LOS C or better.
  • Generate enough revenues to support ongoing operations and maintenance.
  • Support new express transit service through toll revenues.
  • Improve highway and transit in the corridor.
  • Extend the original reversible lane segment to include and additional 12 miles of converted HOV lanes into an HOT corridor.

5.3.2 Concept of Operations

  • The reversible section was operational only during the AM and PM peak periods and closed during the non-peak period.
  • As the facility expands operations for both HOV and HOT will be 24/7. System will use movable barriers on the new extension.
  • As with the existing reversible sections, HOV 2+ and transit will travel at not cost (free) while SOVs will be tolled for use of the facility. Trucks will not be permitted to use the facility.
  • Current policy only requires SOV users to have a transponder. However, transponder use for HOV users is under consideration.
  • While under consideration, there is currently no electronic enforcement, only manual enforcement provided by enforcement officers.
  • Dynamic Pricing has been employed from the initial pilot system. Toll rates vary, on average from $.50 to $4.00 with a maximum of $8.00.

5.3.3 Innovative Project Features

  • Having local and state leadership engaged in discussions early and often throughout the planning and design phases.
  • Using dynamic pricing with adjustments based on time of day, congestion levels, and travel time differential with the general purpose lanes. Rates may be adjusted every 6 minutes.
  • Sharing revenues with BRT in corridor widely accepted by transit agencies and the public.

5.3.4 Major Project Challenges/Mitigation Actions

  • Higher risk of SOV use violations with continued manual enforcement by CHP – Prior to the expansion of the I-15 Express Lanes, enforcement was easier because it was a reversible lane facility that allowed access at a single toll point, with wide shoulders and one enforcement area. With multiple access points and limited shoulder widths, mobile enforcement will be needed to effectively target toll violations.
  • The implementation of dynamic pricing required both local public and political support. Early and frequent (on-going) public awareness initiatives that included public outreach, active marketing and surveys contributed to the ready acceptance of dynamic pricing.

5.3.5 Major Lesson Learned

  • Enlist the support of a strong political champion at both state and local levels to provide advocacy for HOT lane conversion.
  • Roll out an extensive public outreach program involving stakeholder interviews, focus groups, and taskforces in parallel with early project planning efforts.
  • Conduct corridor level market research early in the project and update frequently.
  • Share information and research among other agencies, especially those involved along the corridor.
  • Recognize the need for employing ITS technology to enhance the program and for adding to regional ITS capabilities.

5.3.6 Keys to Project Success

  • The HOT program must provide viable and recognized travel options for the public.
  • For project acceptance strong stakeholder and public outreach programs are a necessity.
  • When possible it is important to develop a revenue plan that includes a transit component.

5.4 Minneapolis, MN I-394 Express Lanes

The I-394 Express Lanes, better known as MnPass, became operational in May 2005 and has nearly two years of operational lessons learned since it opened.

5.4.1 Project Objectives

  • To improve efficiency of I-394 and to increase person and vehicle carrying capabilities of the HOV lanes.
  • To maintain free flow speeds for transit and carpools.
  • To improve highway and transit operations in the corridor with the revenues generated.
  • To use electronic toll collection without toll booths.
  • To employ dynamic pricing and in-vehicle electronic enforcement.

5.4.2 Concept of Operations

  • Conversion of the existing HOV lanes to HOT lanes with concurrent travel to be operated 24/7 while operating the two-lane reversible section for HOT operations EB during the AM Peak and WB for the PM Peak.
  • Only SOVs are tolled while HOV 2+ and Transit are not tolled (free). Trucks are not permitted to use the facility.
  • For the non-reversible section there is no barrier between the HOT lanes and adjacent GP lanes. Only double white stripe is used to delineate HOT-GP separation.
  • For the HOV converted segment there are multiple mid-point access locations to the HOT facility. Access to and from the reversible lane segment is controlled by three gates that are closed manually prior to beginning reverse operations.
  • Variable dynamic tolling is used during peak travel times with an average toll rate between $1 and $4, with a maximum of $8.

5.4.3 Innovative Project Features

  • The engagement of state leadership early and often throughout the planning and design phases was instrumental in passing key legislation and project acceptance.
  • A local taskforce, the I-394 Express Lane Community Taskforce, was created to address issues, desires and design options.
  • The program received local and state support by ensuring that 50% of revenues generated were shared with transit for improvements.
  • To maintain support and to encourage continued growth, it is important to conduct continuing and comprehensive evaluations of the facility to provide to the public and for use in marketing campaigns.

5.4.4 Major Project Challenges/Mitigation Actions

  • Prior to the conversion to HOT lanes there was a high rate of HOV lane violations, over 20%. To maintain the integrity of the HOT facility a more effective enforcement presence was needed to detect and to deter violators. Mobile violation detection equipment was employed along with contracts with three law enforcements agencies along the corridor to beef up law enforcement presence. Contracts are with Minnesota Highway Patrol, Minneapolis Police Department and the Golden Valley Police Department.
  • Opposition from pro-transit constituent groups had to be convinced that HOT lanes would provide a strong benefit to transit. With the strong projections provided from the Toll and revenue studies, and the proposed sharing of the revenue generated, the pro-transit constituent groups became strong supporters.
  • The added SOV traffic on the HOT lanes created unexpected traffic backups in the downtown area that increase congestion. After opening of the HOT facility MnDOT constructed an auxiliary lane to provide additional vehicle storage capacity to mitigate the congestion created by the added SOV traffic.

5.4.5 Major Lesson Learned

  • Have a fiber backbone and communications infrastructure in place to implement an effective traffic management system.
  • The establishment of the I-394 Express Lane Community Task Force was critical to getting buy-in from the Governor, state legislators, and community groups. It provided an opportunity for the community to engage the decision makers early and often through a participatory process.
  • Don’t create new traffic problems and be prepared to add capacity to address unexpected congestion hot spots.

5.4.6 Keys to Project Success

  • Implement an effective enforcement strategy to regulate demand and to maintain the integrity and effectiveness of the facility.
  • Establish a robust public outreach and coordination framework through which to build political and public support.
  • Develop a revenue plan that featured a transit component was critical in earning the trust and support of the transit community.

5.5 Denver, CO I-25 Express Lanes

The I-25 Express Lane opened in June 2006. Like SANDAG’s I-15 Express Lanes, I-25 Express Lanes consists of two segments: a 2-mile reversible segment and a 7-mile barrier-separated HOT lane segment.

5.5.1 Project Objectives

  • Improve the efficiency and capacity of I-25 HOV/HOT lanes.
  • Expand menu of travel options to the motoring public.
  • Use the facility as a showcase congestion management tool.
  • Generate sufficient revenue to cover operating expenses.

5.5.2 Concept of Operations

  • The reversible section is operational during AM and PM peak periods. During non-peak periods the section is open outbound only.
  • The HOT section (converted HOV) is only operational during the AM and PM peak periods.
  • The entire facility is barrier separated with single entry and exit points.
  • SOV’s are tolled for use, while HOV2+ and transit travel without being tolled (free). Trucks over 3-axles using the facility are charged a premium rate of $18.00 plus the base toll rate which is per axle based.
  • All HOT users, SOV, bus and trucks are required to have transponder.
  • A fixed variable toll rate based on time of day dynamic tolling is used. Toll rates average between $.50 to a maximum of $3.25).
  • VES enforcement is automatic using license plate photo and optical character recognition technology.

5.5.3 Innovative Project Features

  • Instead of using LOS, bus travel speed is used as a performance measure on travel time. If bus speeds or time degrades by 8 min, 45 seconds then the toll rate is raised to push SOVs off of the facility. The tolls are increased on a pre-determined fixed amount based on time of day.
  • The facility has single ingress and egress points with the northern section interfacing to two distributor connections and the southern end feeding directly into downtown.
  • The facility has a single tolling point that requires traffic to divide into lanes for HOVs (free) and non-HOV (tolled) vehicles.
  • During off peak hours the reversible lanes are switched using multiple gates along the facility to restrict access from direct access ramps. All gate closing is completely automated.
  • Customer Service Center is outsourced to existing E-470 Service Center

5.5.4 Major Project Challenges/Mitigation Actions

  • HOV/HOT violations are captured automatically for undetected transponder reads using V-tolls, or video tolls.
  • Vehicle occupancy violations done by visual on-site inspection by Highway Patrol.
  • Automatic vehicle classification system is required for axle classification needed to capture trucks with more than three axles.
  • The reversible lane section in downtown required that travel through the section be safely and efficiently revered. Gates are used at the entrance and exit points as well as the direct access ramps to restrict access. Gate closing is completely automated, is done during off-peak hours is connected with traffic operations via a verifiable communication link to verify gate status.

5.5.5 Major Lesson Learned

  • Have a political champion to ensure successful project implementation.
  • Avoid justifying HOT lanes implementation as a revenue generation strategy for added capacity. Establish the primary program objective of HOT lane implementation as a congestion management tool.
  • Ensure that managed lane projects are included in MPO plans early.

5.5.6 Keys to Project Success

  • Promote future projects as “congestion relief” and promote early to the public. Don’t promote revenue enhancement; advocate use as a congestion tool.
  • An effective enforcement strategy is a must for a success.
  • A strong political champion at both state and local levels is key to successful project development and implementation.

June 2007
Publication #FHWA-HOP-08-034