In 2016, the City of Chino Hills invited the City of Brea to collaborate on a preparation of a preliminary traffic study to analyze issues related to traffic volumes, operations and truck traffic safety along Carbon Canyon Road (SR 142). Carbon Canyon Road, also known as State Route 142, is under the jurisdiction of the California Department of Transportation (Caltrans). The City of Brea agreed to participate at no cost. The roadway spans across San Bernardino and Orange Counties and is often used as a commuter thoroughfare. The segment through Carbon Canyon is approximately 8.4 miles from Chino Hills to Brea and is maintained by two separate Caltrans Districts; District 12 (Orange County) on the Brea side to the County Line, and District 8 (San Bernardino County) on the Chino Hills side to the County line.
In 2017, the City of Chino Hills completed the study and shared a Technical Memorandum and its findings entitled “Carbon Canyon Road (SR142) Corridor Initial Study – Phase I” dated March 13, 2017. This Initial Study gathered traffic speeds, collision data, field observations, traffic volume counts, roadway geometrics and truck traffic maneuverability. In the City of Brea, the accident history showed, from a period of December 2010 to November 2015, 29 collisions (primarily rear end) with a primary collision factor of unsafe speed. This is within the vicinity of the Chino Hills Discovery Center entrance and at the intersection of Valencia Avenue. Many of the findings had recommendations to proceed with Phase II of the study, which would include a full in-depth analysis of the corridor.
In 2018, Chino Hills asked Brea if it would to partner in preparation of Phase II of the Carbon Canyon Corridor Study. The Phase II Study was to comprehensively analyze traffic volumes, speeds, collision history, traffic calming and intersection delay times. The total cost of the study was $70,000. Since most of the significant findings in Phase I affected Chino Hills, Chino Hills offered to pay for $50,000 of the Phase II Study. Brea City Management agreed to participate in this study at a cost of $20,000 under City Manager discretionary authority.
One of the study’s primary emphasis was to focus on large-truck traffic issues to overcome some of the traffic and safety challenges in this corridor. In Brea, the Phase II Study analyzed the following four (4) signalized intersections and one (1) non-signalized intersection.
- Carbon Canyon Road at Olinda Place
- Carbon Canyon Road at Ruby Street
- Carbon Canyon Road at Brea Hills Ave (non-signalized)
- Carbon Canyon Road at Santa Fe Road
- Carbon Canyon Road at Valencia Avenue
The Phase II Study was completed in October 2018, and had four (4) recommendations within the City of Brea. The table below shows two intersections with a Level of Service (LOS) E, which is an unacceptable LOS. A LOS of A is the best performing operation and F being the worst. The City’s Traffic Impact policy within the General Plan defines a LOS of D or better at any intersection to be acceptable.
| Intersection |
|
AM LOS |
PM Peak |
| 1 |
Carbon Canyon Road/Olinda Place |
E |
A |
| 2 |
Carbon Canyon Road/Ruby Street |
B |
D |
| 3 |
Carbon Canyon Road/Brea Hills Avenue |
D |
B |
| 4 |
Carbon Canyon Road/Santa Fe Road |
C |
C |
| 5 |
Carbon Canyon Road/Valencia Avenue |
E |
D |
Notes: LOS = Level of Service, Delay shown at stop controlled intersections
reflects delay at worst case stop controlled approach
As shown within the following section, recommendations numbers 1 and 2 from the Phase II Study propose to improve the LOS E at the intersections on Carbon Canyon at Olinda Place and Valencia. Recommendations number 3 will address the speeding found in a certain segment within the City of Brea. Recommendation number 4 proposes the prohibition of trucks, within a certain overall length, to use Carbon Canyon (SR 142).
PHASE II STUDY RECOMMENDATIONS
- Olinda Place at Carbon Canyon Road Intersection
To improve the deficient a.m. peak hour traffic operation, an additional westbound through lane would be required. In order for this improvement to function properly, widening would be required to add a westbound through lane at the downstream Ruby Street intersection, which would continue west of the intersection. These improvements are not considered feasible due to the immediate uphill slope north of Carbon Canyon Road.
- Valencia Avenue at Carbon Canyon Road Intersection
This intersection is operating at a deficient Level of Service (LOS) during the a.m. peak hour. This deficient operation is primarily caused by a heavy westbound left?turn volume of 862 vehicles. In order to improve the operation of the intersection, a third westbound left?turn lane would be required. However, this improvement would not be feasible without widening the south leg intersection departure to accommodate three lanes of traffic. Currently, southbound Valencia Avenue consists of two travel lanes and a bicycle lane in this section. The feasibility and cost effectiveness of this measure would require further study.
- Speed Feedback Signs
To install speed feedback signs at two (2) locations:
1. On Carbon Canyon Road just east of Olinda Drive
2. On Carbon Canyon Road just east of East Santa Fe Road
The installation of speed feedback signs along roadways where vehicles typically travel at higher speeds can result in drivers slowing down, particularly in the immediate timespan following installation. Speed feedback signs can enhance drivers’ awareness of the posted speed limit and encourage drivers to comply with the law. By displaying both the posted speed limit and their actual traveling speed, motorists are reminded how far above the speed limit they are traveling. There are various types of solar and/or battery powered signs available.
- Truck Restrictions
With the increasing number of major traffic delays and safety concerns during peak traffic hours along Carbon Canyon due to truck traffic, the Phase II Study specifically analyzed this issue. The study collected data along with 24-hour video camera footage of the Carbon Canyon road segment that included the switchback area in Chino Hills. The footage was collected over a period of seven days. The purpose of the video collection was to observe heavy truck maneuvers down the hill, specifically at the two sharp curves. During the course of the video collection, multiple occasions were observed where heavy trucks either slightly infringed or fully crossed over the roadway centerline. Some trucks were observed crossing the centerline by approximately 4 to 5 feet at the beginning of their turn and up to approximately 12 feet at the end of their turn. This finding led to the recommendation to permanently prohibit certain lengths of trucks on Carbon Canyon Road.
City of Brea staff reviewed the Phase II recommendations for items one (1) through three (3) above and determined that there is no immediate need at this time. Staff will be reviewing and studying these recommendations to verify the merits of the improvement in comparison to the entire City’s needs and infrastructure.
After discussions between both cities, it was decided that the first action should include restricting large trucks on Carbon Canyon (Number 4). Since Carbon Canyon is controlled by the State, a formal request to restrict truck traffic would have to be submitted to Caltrans. Prior to submittal to Caltrans, the City Councils of both cities must adopt resolutions, which request Caltrans to restrict large-truck traffic from using this roadway. A draft Resolution is attached to this Staff Report for City Council’s consideration (Attachment A). If approved, the Phase II Study and resolutions from the two cities will then be submitted to Caltrans for their review. Once approved, the local Caltrans Districts (Districts 8 and 12) will forward the Phase II Study along with a recommendation to their headquarters in Sacramento for final approval. This process may take several additional months, if all proceeds as desired.
Therefore, as requested by the City of Chino Hills, staff recommends that City Council adopt a Resolution to prohibit vehicles and combination vehicles with an overall length greater than 30 feet kingpin-to-rear axle on Caron Canyon Road (State Route 142). Both cities will individually consider other recommendations identified in the Phase II Study in the future.
On March 26, 2019, the City of Chino Hills approved a resolution recommending the prohibition of vehicles and combination vehicles with an overall length greater than 30 feet kingpin-to-rear axle on Carbon Canyon Road (State Route 142). |