SM 101 - Managed Lanes Project (MLP)

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Getting More Passengers though the Busy Corridor

Silicon Valley produces between 20- 25% of California's annual gross domestic product. While this economic juggernaut has fueled revenue and job growth, it has also created overcrowding on San Mateo Highway 101, the major commute route between San Francisco and Silicon Valley.

The rush hour starts earlier and ends later. Travel times have increased while predictablity has decreased. A diabled vehicle at peak hour can create a ripple effect can last for minutes or hours, depending on the speed in which a tow truck can weave throught the backup.

The impacts are economic as well as social. More time commuting means less time being productive at work and fewer hours relaxing at home.

Getting people out of their cars and onto transit has helped, but it’s difficult to promote bus riding when a major incentive is lacking. Highway 101 in San Mateo County has no carpool lane. Buses and carpoolers must ply the same congested lanes as solo drivers.

Shifting traffic patterns have exaserbated congestion. More workers are choosing to live in San Francisco, making a long trip to work and back each day. When motorists drive longer distances, it adds traffic to each bottleneck along the way.

A Solution for an Urban Corridor

Widening projects in urban corridors are fraught with expensive and time-consuming right of way problems. Anyone living on the peninsula for a long time knows that Highway 101 has been widened many times. The question is whether there is any more space for a widening project? It’s an important question because acquiring large swaths of property for freeway expansion is out of the question. The price of real estate in San Mateo County is far too expensive and the process of eminent domain is far too time consuming.

Caltrans engineers found a solution by shifting centerline of the freeway, threading it through the right of way and keeping the shoulders within Caltrans-owned land. A six-foot strips of frontage road will need to be acquired, but that’s all.

The widening won’t be typical. The plans require removing striping and reconfiguring lanes. But the time savings of eliminating right of way issues will be enormous, taking years off the project. Construction is due to begin in May 2019 with the project finishing two year later.


How will this be done?
  • Connect all auxiliary lanes in San Mateo County, converting them into through-lanes.
  • Construct new auxiliary lanes where they are needed.
  • Convert the HOV lanes from Whipple Avenue to Matadero Creek into Express Lanes
  • Build a tolling system that uses FasTrak to collect tolls
Why an Express Lane

One of the best solutions to congestion is to focus on passenger throughput, not vehicle throughput. That would involve HOV or HOT Lanes, collectively known as managed lanes.

Traffic engineers decided that the best solution for this corridor would be an express lane, where the toll operators could adjusting the price of travel according to congestion and the number of occupants per vehicle.

Managing the Express Lane

Traffic engineers have guidelines* for predicting congestion based on traffic volumes. Caltrans looks for a traffic volume of between 1600-1650 vehicles per hour to keep congestion from occurring in the managed lane.

Proposed hours of operations are 5 am – 8 pm.

Tolls will be adjusted as if by a dial. When congestion occurs, tolls will be “dialed up” which would mean that Single Occupant Vehicles (SOV) pay a toll and HOVs with 2 persons pay a reduced toll

Carpoolers with 3 or more persons will be exempt from tolls. SOVs will always pay a higher toll than a carpooler with one passenger. But tolls will vary according to the congestion level. The point is to keep traffic flowing at 45 mph or faster within the express lanes

*Other factors besides traffic volumes can create congestion: weather, accidents, debris in the road, etc.

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Related Reading:

Silicon Valley Express Lanes:

San Francisco Transportation Authority Study of Carpool and Express Lanes:

Project Links

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