Project Details

Purpose and Need

Purpose

The purpose of the project is to:

Improve traffic flow and operational performance on a steep grade section of State Route 58 eastbound where the existing truck speeds fall 30 miles per hour or more below the posted speed limit.
Improve commuter travel and move freight more efficiently through the interregional corridor.

Need

State Route 58 within the project limits is a four-lane expressway/freeway with an at-grade intersection at Bealville Road (westbound)/Bena Road (eastbound) and controlled access elsewhere. The project is in a hilly area with an average grade of 5.7 percent, a maximum grade of 6.01 percent, and a total rise of 829 feet over 3.5 miles (from post mile 76.3 to post mile 79.8). The posted speed limits are 55 and 65 miles per hour; however, the average freight truck speed drops between 20 and 30 miles per hour at the steepest sections.

The Caltrans Highway Design Manual states that truck climbing lanes should be considered where truck speeds fall 10 miles per hour or more below the running speed of remaining traffic and a truck climbing lane should be considered for sustained grades greater than 2 percent where the total rise is greater than 250 feet.

Slow trucks in the number two (inside/slow) lane force the passenger cars to stack in the number one (fast) lane. The high traffic density from the truck vehicle speed reduction causes a drop in operational speed for all lanes resulting in increased traffic congestion and inefficient flow of traffic. Traffic density and vehicle speed reduction is compounded when slow-moving trucks merge into the fast lane attempting to pass slower moving trucks.

The Caltrans District 9 Traffic Safety Office conducted a Traffic Index Calculation analysis in May 2022 to forecast the increase in traffic within the project area. The analysis used Caltrans 2020 census data from the vehicle count station at post mile 90.72. The analysis assumed a 3.17 percent annual growth rate in Annual Average Daily Traffic. Annual Average Daily Traffic is the total volume of vehicle traffic on a highway for a year divided by 365 days.

Census data indicates that the eastbound Annual Average Daily Traffic makes up 57.1 percent of the total Annual Average Daily Traffic. The data also indicates that truck volumes are 34.74 percent of total traffic volume. The analysis forecasts that the eastbound truck traffic on State Route 58 will increase by 43 percent from 1,757,208 trucks per year in 2020 to 4,081,344 in design year 2047, 20 years following completion of the proposed project. Total eastbound vehicle traffic on State Route 58 will increase from 5,058,170 vehicles per year in 2020 to 11,748,255 in design year 2047.

Additional growth in truck traffic volume is anticipated as major distribution centers continue to be built in the San Joaquin Valley. Development of major inland ports being planned in the cities of Shafter and Mojave can be expected to increase truck traffic volumes, and additional traffic is anticipated with the completion of the Centennial Corridor, Westside Parkway, and Stockdale Highway projects, which will extend State Route 58 to connect Bakersfield and Interstate 5 with new freeway. Currently, there are over 184 distribution and logistics centers (with an estimated combined facility size of over 52 million square feet) in the South San Joaquin Valley that rely on State Route 58 to provide truck access to the eastern states. The Tejon Ranch Commerce Center, south of the junction of Interstate 5 and State Route 99, uses Wheeler Ridge Road to State Route 223 to State Route 58 (at the base of the proposed truck climbing lane) to ship east, or to access Southern California when Interstate 5 is closed due to inclement weather.

Project Description:

A Build Alternative and a No-Build Alternative are under consideration.

Build Alternative

The Build Alternative will install an eastbound 12-foot-wide truck climbing lane, upgrade shoulder widths to the standard 10-foot width, construct a 5-foot maintainable dirt strip situated outside the paved shoulder, and modify the at-grade intersection at Bealville Road and State Route 58. The Build Alternative will also improve drainage, including removal of debris blockers to enhance wildlife connectivity, install post-construction stormwater treatment Best Management Practices, upgrade guardrail, update and install signage, relocate streetlights at the Bealville intersection, and install rumble strips.

Large cut and fill slopes will be required to construct the improvements. The existing condition between post miles 76.3 and 77.2 includes a 7-foot-wide inside shoulder and a standard 3-foot-wide maintainable dirt strip beyond the outside paved shoulder. For this post mile range, the project will widen the existing 7-foot shoulder to 10 feet, install a 12-foot-wide truck climbing lane, and widen the existing 3-foot maintainable drip strip to 5 feet. Therefore, the total widening between post miles 76.3 and 77.2 would be 17 feet. For the remainder of the project limits, post miles 77.2 to 79.8, the existing inside shoulders meet the standard 10-foot width. The project will install a 12-foot-wide truck climbing lane and widen the 3-foot maintainable dirt strip to 5 feet. Therefore, 14 feet of total widening would occur between post miles 77.2 and 79.8. A cross section diagram displaying existing conditions and proposed work is shown below on the desktop version of this website.

Where feasible, the project will minimize the need to import material by reusing earthwork materials generated onsite. Currently, a geotechnical study is being conducted to determine slope stability in areas requiring steep road cuts to reduce the need to construct retaining walls.

The Bena Road at-grade intersection (post mile 77.06) will be removed to provide access control. Removing this connection will eliminate cross traffic in an existing conflict area. The left-turn pocket from westbound State Route 58 to Bena Road will be removed, and traffic will be diverted 1.4 miles west to the intersection of State Route 223 and State Route 58. The existing westbound left-turn pocket onto Bena Road will be re-striped to provide an acceleration lane for vehicles exiting Bealville Road to travel eastbound on State Route 58. These modifications to the intersection and proposed access control measures will eliminate an existing conflict area and enhance highway operations. A diagram of the changes is provided in a figure below in the desktop version of this website.

Installation of Permanent Post-Construction Stormwater Treatment Best Management Practices (BMPs) will be implemented to treat the additional stormwater coming off of the new impervious surface created by the roadway widening. Design Pollution Prevention Infiltration areas, infiltration basins and traction sand traps will be implemented to treat the additional stormwater.

The project will also extend culverts and install overside drains to accommodate the roadway widening and remove the existing debris blocker at the Clear Creek culvert and potentially other culvert inlets to promote use by wildlife. Other roadside improvements include installing rumble strips, replacing guardrail, replacing and upgrading signage to meet current standards, relocating the lighting near the at-grade intersection of Bealville Road and State Route 58 and replacing portions of the existing standard right-of-way fencing with wildlife fencing.

The Build Alternative will extend the large 6-foot-diameter culvert at Clear Creek (post mile 78.70) and install a debris deflector separated from the culvert headwall. A figure below shows the proposed work at this location on the desktop version of this website. The existing culvert has a debris gate attached to the culvert headwall that blocks wildlife from accessing the culvert to cross under the highway. The proposed separation between the culvert entrance and debris deflector will allow for the passage of wildlife through the culvert.

Acquisition of additional right-of-way and temporary construction easements will be required to accommodate the widening and construct the project.

Build Alternative:

The build alternative, as described above, would widen a segment of State Route 58 in order to construct a truck climbing lane. The build alternative will also improve drainage, including removal of debris blockers to enhance wildlife connectivity, install post-construction stormwater treatment Best Management Practices, upgrade guardrail, update and install signage, relocate streetlights at the Bealville intersection, and install rumble strips.

No-Build (No Action) Alternative:

The No-Build Alternative will maintain the existing facilities on State Route 58 within the project limits as-is. The No-Build Alternative will result in continued operational issues due to reduced truck speeds while climbing the grade. Under the No-Build Alternative, no changes will be made to facilitate improvements to traffic flow and operational performance. The continuation of the existing traffic flow for commuters and freight would not meet the project purpose and need. Under the No-Build Alternative, traffic congestion will worsen based on the forecasted increase in truck and vehicle traffic volumes by design year 2047.

Project Features

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Cross section diagram

Between post miles 76.3 and 77.2 (bottom diagram), the project will widen the existing 7-foot shoulder to 10 feet, install a 12-foot-wide truck climbing lane, and widen the existing 3-foot maintainable drip strip to 5 feet. Therefore, the total widening between post miles 76.3 and 77.2 would be 17 feet.

For the remainder of the project limits, post miles 77.2 to 79.8 (top diagram), the existing inside shoulders meet the standard 10-foot width. The project will install a 12-foot-wide truck climbing lane and widen the 3-foot maintainable dirt strip to 5 feet. Therefore, 14 feet of total widening would occur between post miles 77.2 and 79.8.