sloRecent U.S. Highway 101 upgrades in SLO County bring corridor needs into focus

February 26, 2011

By RICHARD KRUMHOLZ

Caltrans has received some questions lately regarding a recently completed project in the south county. Meanwhile, motorists throughout the county are experiencing more frequent and often unpredictable delays along the US 101 corridor. While addressing this issue, it is important for me to also highlight an underlying and growing need facing the central coast.

Specifically, I’ve been asked why the climbing lane on southbound US 101 from Avila Beach Drive does not extend all the way to the Spyglass Drive exit in Shell Beach. The purpose of this third lane is to allow slower moving traffic going uphill to move right so that other traffic can pass while maintaining speed. This reduces conflicts between slower and faster moving vehicles. As a result of this climbing lane project, we have seen fewer collisions involving vehicles traveling at different speeds since its completion in the spring of 2009.

The new lane ends just beyond the crest of the roadway and before the Spyglass Drive exit. Ending the lane before the exit follows a key principle of roadway design:  provide enough space for drivers to make one decision at a time. On the flatter area over the crest, slower moving traffic has time to get back up to prevailing speeds and safely merge into the flow. This merge happens before drivers make another decision and eliminates any competition between vehicles merging and exiting.

This decision sequence differs from what drivers experience with auxiliary lanes, also known as merge or weaving lanes. Last year, we completed construction on a series of these lanes on US 101 between several interchanges in Pismo Beach and Arroyo Grande. These lanes work by alleviating conflicts between vehicles entering and exiting the freeway, which allow drivers to equalize speeds and then exchange places between on/off-ramps.

Still, drivers are becoming increasingly frustrated as US 101 reaches its service capacity. We have all experienced travel delays during morning and evening peak commute times throughout the county.

Unfortunately, more congestion not only slows us down, it increases the probability for traffic incidents. With increasing frequency, these incidents cause significant delays affecting the daily commute. While bottleneck areas at certain times of the day are predictable, incidents cause delays that are very unpredictable. All of this threatens the reliability of our main transportation corridor, which undeniably serves as the backbone for this county and the entire central coast region from Santa Barbara through Monterey County.

It is clear that we must continue investing in the right projects throughout San Luis Obispo County and elsewhere on the central coast to keep the Highway 101 corridor vital and healthy.

So, with an opportunity to address the intermittent bottleneck near Avila Beach Drive, we constructed a climbing lane. In order to reduce conflicts created with closely spaced on/off-ramps, we built auxiliary lanes. These types of projects address problems at spot locations but cannot alleviate the underlying demand that continues to grow in this corridor.

This fall, Caltrans will begin construction on a long-awaited project to widen the bridges over the Santa Maria River at the county line. This $50 million project will improve traffic flow for all vehicles with a third lane in each direction and it will provide safe connectivity for bicycles and pedestrians with a separated two-way path on the western side of 101.

We also recently improved the interchange and freeway merge at Highways 41/101 in Atascadero and are working with the City of Paso Robles to make spot improvements along US 101 between Highways 46 West and East.

However, answering the demand does not always mean adding freeway lanes. A variety of solutions may include frontage roads, interchange modifications and elimination of intersection crossing movements as well as efforts that make transit and passenger rail more viable. We need meaningful, comprehensive upgrades that meet the future needs of the central coast community.

We’re working with our partners, the San Luis Obispo Council of Governments (SLOCOG), to focus on US 101 as a top regional transportation priority. Furthermore, this partnership is expanding with our neighboring central coast counties of Santa Barbara, Monterey and San Benito on a newly- formed coalition to address the critical needs along the corridor, our central coast lifeline.

If we value our coastal quality of life and hope to preserve our economic vitality, we need to face this issue head on by identifying and investing in the best projects for the greatest benefits. A good place to focus our energy is in regional transportation planning and SLOCOG is in an important position to shape our future. They need our input and support them in this role.

Richard Krumholz is Caltrans’ District 5 Director.