California Department of Transportation District 1
 

Lake 29 Improvement - Purpose and Need

The need to provide a safe, reliable, and modern transportation facility along SR 29, a Federal Aid Primary Route that together with Routes 20 and 53 (around the south shore of Clear Lake) forms the Lake County portion of the SR 20 Principal Arterial Corridor from U.S. 101 to Interstate 5, has been long recognized. In 1988 the Lake County/City Area Planning Council and Caltrans joined in a cooperative effort to determine appropriate Route Concepts for state highway routes in Lake County and to establish highway development priorities. The Route Concept selected for this Principal Arterial Corridor was a 4-lane freeway/expressway within a "C" concept Level Of Service (LOS).

The development of basic industries in Lake County has been impeded by the difficulty of transporting goods in and out of the county. The 2001 Lake County Regional Transportation Plan states "the current condition of the State highway system throughout the region limits economic development activities due to poor, inefficient access to most areas within the County. It is critical to the economic future of Lake County that the Principal Arterial Corridor be improved. Widening to accommodate the ever-increasing through traffic and goods movement between Interstate 5 and U.S 101 is essential."

The SR 20 corridor is also identified as a Focus Route in the Caltrans Interregional Transportation Strategic Plan (1998), having statewide significance, and is one of ten corridors in the state to receive highest priority for completion to minimum 4-lane expressway facility standards over the next 20 years.

This project, as proposed by the California Department of Transportation, the Lake County Area Planning Council (LAPC), and the Federal Highway Administration (FHWA), will widen SR 29 to a 4-lane divided expressway with access control. The total length of the project is approximately 8.0 miles and is located between the communities of Lower Lake and Kelseyville.

The proposed project will start at the top of the Glasgow grade (Diener Drive), about 3.3 miles north of the town of Lower Lake. For northbound traffic, the top of the Glasgow grade marks the end of two lanes heading in the northbound direction and congestion increases with this loss of the second lane. For southbound traffic, this terminus is also logical as the four-mile transition length between the SR 29/281 intersection and Diener Drive will provide traffic a sufficient distance to disperse, allowing for an even flow of vehicles from the improved facility to the un-improved facility south of Diener Drive. The proposed project will end just north of the SR 29/175 intersection, which will address the "directional split" encountered at this location with traffic volumes increasing in the southbound direction caused by traffic merging onto southbound SR 29 from SR 175. This end point will also allow for the realignment of the SR 29/175 intersection to meet current standards.

Lake County has experienced rapid growth in both population and vehicular travel in the last 20 years and traffic forecasts indicate vehicular volumes on this section of SR 29 are expected to nearly double over the next 20 years. Currently, SR 29 within the project limits operates at a "D" LOS. The LOS is expected to deteriorate to "E" by the year 2021 if no capacity increasing improvements are made, causing significant delays. For that reason, implementation of the proposed project will dramatically improve the LOS, volume to capacity ratio, traffic queuing, and decrease traffic delays over the no-build alternative. Additionally, SR 281 is a major entry and exit point for this area and the intersection of SR 29/281 experiences significant congestion and delays. With the no-build alternative the LOS for the intersection of SR 29/281 is at LOS "E" and drops to LOS "F" in 10 years.

This project is also expected to significantly increase overall safety to motorists, providing a modern four-lane facility that meets current design standards. Improvements to the horizontal and vertical alignment, additional lanes that will create additional passing opportunities, removal of fixed objects, widening of shoulders, and the addition of a 46 ft median will provide safety benefits to motorists in terms of increased sight distance, enhanced recovery areas, separation of traffic, and minimizing exposure to fixed objects. A collision analysis of this segment of highway revealed that between 01/01/2000 and 01/01/2005, there were 162 collisions, 70 of which resulted in injuries and one of which was fatal. This number of collisions equates to 1.10 collisions for every million-vehicle miles traveled within the segment. Although this collision rate is typical of a rural two-lane highway, upgrading the facility to a modern four-lane expressway will significantly reduce this rate. The statewide average for a four-lane expressway is only 0.50 for every million-vehicle miles traveled. As this project will be built to the most current design standards, it is reasonable to assume that the collision rate will be at or below the statewide average, and that collisions will be reduced by almost 60 percent.

Finally, upgrading SR 29 to a four-lane expressway would divert traffic (including trucks) from the "Main Street" communities along the north shore (including Nice, Lucerne, Glenhaven, and Clearlake Oaks), where the safety of pedestrians and non-motorized traffic as well as traffic noise have been ongoing concerns. This 23 mile segment of SR 20 was recently designated a Pedestrian Safety Corridor as a result of a collaborative effort between Caltrans, the CHP, and local businesses and residents. Ultimately, it is envisioned that interregional traffic (including truck traffic) between U.S. 101 and I-5 will use the SR 20 Principal Arterial Corridor around the south shore of Clear Lake.