Colorado I-70 Eastbound Peak Period Shoulder Lane (PPSL):
Summary of project, including design and operational elements
Revised December 15, 2014
Project summary
Overview - The I-70 Eastbound Peak Period Shoulder Lane (PPSL) involves the repurposing of the left freeway shoulder, minor widening, ramp realignments, two bridge replacements, recreational path and park improvements, and related design and operational elements to implement peak period use of the left shoulder as a managed lane under a variable tolling arrangement. The PPSL is intended to provide immediate congestion relief – increased capacity and reduced delays – at a comparatively low cost for the traveling public.
Context – While the PPSL is expected to be in place for many years, it is not the “permanent” solution for the corridor and is categorized as an interim, operational improvement by FWHA. The temporary nature of the project enables the use of less than “ideal” design characteristics, and the result is accelerated relief for travelers, less environmental and community impacts, and substantially lower project costs.
Existing traffic – During congested periods, existing delays can reach up to 2.5 hours to travel 8 miles. Around 90% of travelers have a recreational trip purpose; this PPSL located west of Denver, CO is not a typical commuting relief solution.
Environmental review – The project is entirely within the existing right-of-way for I-70, and the operational nature of the project fit into FHWA’s Categorical EXclusion (“CatEx” or “CE”); which was completed in approximately 9 months.
Expected operational and safety impacts - Vehicle-miles traveled (VMT) will increase slightly as a result of the additional capacity, while vehicle-hours traveled will drop significantly due to the reduction in congestion. A time savings for PPSL users of approximately 30 minutes during peak periods is expected; general purpose lane users will also experience (smaller) time savings due to overall increased capacity. Frontage road users will get their local roadway back as “rat running” behavior decreases. Safety is expected to be the same or better than with the current configuration.
Construction timetable – Construction of the PPSL along I-70 EB began during summer 2014. It is expected to be complete in fall 2015.
Project cost - $70 million.
Termination of operational improvement – As noted above, FHWA treats this peak period shoulder lane as an interim, operational treatment, and this managed lane will cease operation by 2035, per a Memorandum of Understanding (MOU) between CDOT and FHWA, unless modified by a different project. This means that there is an anticipated 20 year operational life for the PPSL.
Colorado I-70 PPSL, continued
Design characteristics
Corridor length – The PPSL itself is about 9.5 miles long. However, the project limits extend beyond the distance of the proposed PPSL for signage and tie-ins.
Typical section – PPSL – The peak period shoulder lane will be located on the inside (left) side. It will be 11 feet wide, with an additional 1’ paved distance between the yellow stripe to the edge of pavement. There will be no buffer to the adjacent general purpose lane, other than a single 8” solid white stripe, solid throughout the corridor, except that it will be dashed in access zones. In addition to the solid stripe, there will be a “rumble stripe” ground into the pavement to discourage crossing over it and to serve as a lateral, tactile warning for motorists who may drift out of the general purpose lanes during normal operations.
Typical section – Adjacent general purpose lanes – There will be two general purpose through lanes, of 11’ (left) and 12’ (right) width respectively, and a 4’ outside (right) shoulder. This configuration will apply whether or not the PPSL is open. Ramp tie-ins will be adjusted as necessary since part of the existing right shoulder is being modified to serve as a general purpose lane.
PPSL Access – The majority of trips in the corridor are traveling through the project area. As such, there will be no intermediate access points – users enter at the beginning and cannot exit until the end. And unlike the new I-495 Express Lanes on the Capital Beltway in Northern Virginia, there are no separate interchanges or ramps from crossing roadways to the PPSL. The PPSL ties directly into a third lane at the downstream end; this third lane was recently constructed and is a managed lane for roughly 3 miles before the restriction ends and it becomes a general purpose lane back to Denver.
Emergency pullouts – Two emergency pullouts will be installed on the outside (right) side of the roadway to compensate for the reduced right shoulder length. There will not be any pullouts installed on the left (inside) side, due to both space limitations and the fact that the PPSL functions as a shoulder outside of peak periods. Lane-use signals will be installed to allow quick closing of the PPSL.
Colorado I-70 PPSL, continued
Operational characteristics and limitations
Annual maximum PPSL operating times - FWHA and CDOT signed a Memorandum of Understanding (MOU) that defined maximum yearly times of operations due to the interim nature of the project. The facility can be open no more than 20% of the days of the year, including holidays (i.e., 73 days) and no more than 7.5% of the annual hourly time (equivalent to 73 days x 9 hours per day).
Hours of operation – The expected operating days and times for the PPSL are afternoons/early evenings on Saturday and Sunday during peak summer and winter travel seasons, but operations will be flexible and available for use beyond those days or times if traffic congestion conditions warrant, so long as the operating hours stay within the daily and annual guidelines under the MOU.
Seasonality of operation – The PPSL is not anticipated to be open every Saturday and Sunday throughout the year; instead, the expectation is weekends during July, August and December through March, along with special times (holidays and holiday weeks, spring break, special events). As with hours of operation, the PPSL could be open beyond those dates if traffic congestion conditions warrant.
Lane Use Signals (LUS) – LUS will be installed over the PPSL every 1-mile (and only over the PPSL, not the general purpose lanes). When the PPSL is blocked due to a disabled vehicle, a red “X” will be posted and the toll rate signed will indicate the lane is closed. When the PPSL is not open and the lane is a shoulder under normal, uncongested conditions, the LUS will remain blank.
PPSL use restrictions – Trucks with more than 2 axles will not be allowed to use the PPSL due to the lane width, minimum speed requirement, and because there would be no access to a truck Port of Entry within the project limits. The operational concept does permit authorized transit buses to use the PPSL, and exempts them from tolls.
Speed limits – The existing static speed limits for general purpose lanes range from 65 MPH to 55 MPH. Variable speed limit signs are being installed along the corridor. The current concept is to let the PPSL operate under the posted speed limit and adjust the speed limit if warranted by weather and traffic conditions.
Colorado I-70 PPSL, continued
Tolling characteristics and enforcement
Toll objective – The purpose for tolling the lane is to ease overall congestion while providing a reliable trip travel time for those willing to pay. The primary project focus is operations and not revenue.
Toll lane branding – CDOT brands their managed lanes as “Express Lanes” and CDOT is in the process of determining branding for the PPSL. “Express Lane” will be on the overhead guide signs.
Toll rates – Tolls will be displayed on signage electronically and will vary by time-of-day and based upon congestion. Since there are no intermediate access points, there will be only one toll segment.
Toll collection – CDOT allows for both transponder and license plate (video) toll users, though transponders are preferred as they cost less and are more accurately read. A toll surcharge will apply for video toll users.
Toll exemptions – The lane will be tolled whenever it is available for use, and there will be limited or no exceptions, other than emergency and maintenance vehicles. It is possible that the lane could be open to all traffic without toll for emergency operations or if the general purpose lanes are blocked, similar to how the shoulder would be otherwise used during incidents.
Tolling points and enforcement – There will be two toll enforcement points (gantries): one at the beginning of the PPSL when users first enter and another 3 miles downstream. State and local law enforcement will be able to enforce the PPSL. In addition, full CCTV camera coverage will be provided; TMC operators could review video and identify violation trends to aid State Patrol in enforcement, or to publish messages on the LUS to help educate the public. Enforcement during peak periods will be difficult due to the geometric constraints. We are hopeful that the adjacent congestion in the general purpose lanes and steady flow in the PPSL will deter significant crossing over. Automated enforcement is not needed since all toll users are assessed tolls (via transponders and license plates); that said there are always means of violating if the desire is strong enough.
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