California Department of Transportation



Portable Work Zone Barrier
(Balsi Beam)

Over the years many Caltrans employees have been seriously injured or lost their lives while working on or near the California State highways. The Caltrans Division of Equipment developed a truck-mounted, expandable beam that will provide work zone protection comparable to a concrete barrier. The system consists of a tractor-trailer combination, where the trailer extends and transforms into a 30-foot long work zone protector. The Mobile Work Zone Protection Device is now deployed in the field by the Caltrans Maintenance Division to gain experience in its operation and evaluate its performance.

The Balsi Beam was accepted by the American Association of State Highway and Transportation Officials ( AASHTO) Technology Implementation Group (TIG). The TIG helps develop a process to prioritize and select technologies on which to focus implementation efforts and solicit potentially ready to implement technologies.

Transportation Safety and Mobility


As small battery powered embedded micro-controllers (sometimes referred to as "MEMS") have become prevalent throughout industry, DRI initiated a series of projects to assess their applicability for transportation applications. Although initially receiving little support from our Division of Operations partners, these projects eventually led to the development of a start up company, Sensys, who have brought this technology to market as a fully deployed product.

The initial developmental stages of this unit had a number of pitfalls, warranting Operation's concerns. As examples, initially microphones were considered as the primary means of vehicle detection, and the unit was mounted on the road rather than in it (analogous to a "Botts Dot") where it was subject to truck tire impact loading. DRI helped identify and rectify these issues, and now the Division of Operations is one of the strongest advocates of Sensys technology.

The Sensys unit, as deployed, is a very small battery powered magnetometer that is embedded in the pavement. It communicates wirelessly, with a (projected) battery life of 5 years or more. These detectors represent a viable alternative to loop detectors, which, in many cases, can be deployed for a fraction of the installed cost. Unlike loops and most other types of detectors which require hardwired power to run, Sensys units can be located hundreds or thousands of feet from the nearest hardwire, saving considerably on construction installation time and costs.

Sensys uses modern ubiquitous TCP/IP communication. Although the small area of the unit's magnetometer doesn't cover the full lane, and hence the is not as accurate as a (calibrated) loop detector, the use of these modern communication protocols makes the overall detection station generally more reliable than existing Caltrans loop stations. Large scale deployments are planned for District 8 and other areas.

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Inductive Loop Signature Cards

DRI has been evaluating inductive loops signature technology for decades. Inductive loops signature technology involves assessing the small nuances or changes in inductance as traffic passes by which can help to not only count and classify vehicles accurately, but allow them to be re-recognized downstream, so that the true traverse travel time can be calculated. Inductive loops signature technology also helps mitigate crosstalk and attenuation due to long lead length which are typical causes of loop detection errors. Although inductive loops signature technology has been around for a while, existing commercial products did not provide the sampling rate, crosstalk immunity, or accessible communication interface to allow these products to be readily deployable. DRI worked closely with a startup company in this area, Inductive Loop Signature Technology, Inc., in developing a full line of inductive loop signature technology cards. These cards can breath new life into loops long since thought to be "dead", and can save the considerable cost of re-cutting and/or re-trenching loops and leads. These cards are commercially deployed and are readily available for field use.

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Performance Measures System

In the early 1990's, the Division of Research and Innovation started developing a set of traffic analysis tools that evolved into what is now known as PeMS - currently the nation's largest and most sophisticated online traffic database. The majority of Caltrans highway traffic data is archived in PeMS, which contains an ever-growing array of graphical and statistical analysis tools. It has the capability of doing everything from micro scale time series assessments of the causes of traffic buildup on individual links; to area-wide comparative evaluations of traffic congestion strategies between different Districts. It can generate enough charts, graphs, 2 and 3D plots, and tables of virtually everything to keep traffic engineers enthralled for days at a stretch.

PeMS has proved so useful that it is now fully funded by our program partner - Division of Operations, although DRI continues to develop new innovative features and capabilities. PeMS has thousands of users, both in and outside Caltrans.

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Travel Times on Changeable Message Signs

Travel Times on Changeable Message Signs (CMS) provides information on current traffic conditions to drivers while they are commuting. Trip time is the most practical information that commuters can use to assess traffic and adjust their routes. A computer program processes real time data from loop detectors and calculates the predicted travel times. The predictions are sent to TMC, where another program displays them onto the message signs.

Travel Times on Changeable Message Signs

Design and Construction

Evaluation of the Gateway Monuments Demonstration Program

The Gateway Monument Demonstration Program (GMDP) facilitated the construction of freestanding structures or signage along roadways to communicate the name of a city, county or township to motorists. While the GMDP sought to foster partnerships with local entities in the placement and construction of signage, there was a knowledge gap concerning how such signs affected highway safety, as well how they contributed to the local economy, community image and sense of place. Therefore, the research undertaken here sought to quantify the impacts that this type of signage. After completion of the 4-year demonstration program on gateway monuments, the Department received approval from FHWA to make the Gateway Monument program permanent.

Rocklin SignOrange County

Using Reinforced Native Grass Sod for Biostrips, Bioswales, and Sediment Control

The objective of this research was to develop and demonstrate native grass sod for use in sediment control and permanent stabilization of disturbed lands associated with California highways. The research was divided into two components-evaluation of native grass species for inclusion in sod and an evaluation of the sod at a California field site. Various mixtures of native grass seeds, including rhizomatous and bunchgrass species, were evaluated in a greenhouse setting for six California ecoregions. The cost to propagate, harvest and install native grass sod was estimated to be approximately five times greater than the cost of the hydroseed-mulch procedure.

Grass being used on a hill Grass on hill

Construction Analysis for Pavement Rehabilitation Strategies

CA4PRS is designed to identify optimal rehabilitation solutions that balance on-schedule construction production, traffic inconvenience, and agency costs. An additional benefit is attained when CA4PRS results are integrated with macroscopic and microscopic traffic simulation tools for estimating road user delay costs that arise from construction. During the design and construction phases of highway rehabilitation projects, CA4PRS helps transportation agencies, contractors, and consultants:

  • Develop staging construction plans
  • Establish CPM schedules
  • Estimate cost (A) + schedule (B) contracts
  • Calculate incentive/disincentive specifications

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Compliance Crash Testing of K-Rail Used in Semi Permanent

A semi-permanent K-rail barrier was tested in accordance with NCHRP Report 350. The barrier consisted of eight concrete segments 6045 mm in length. The segments were placed on AC pavement and connected with 61.8 x 660 - mm pins. Each segment was secured to the ground using four 25 x 610-mm steel stakes. The barriers were constructed and tested at the Caltrans Dynamic Test Facility in West Sacramento, California.

A total of two crash tests were conducted under Report 350 test level 3, one with an 820 kg sedan, and one with a 2000-kg pickup truck. The results of both tests were within the limits of the Report 350 criteria.

It is recommended that the semi-permanent K-rail be approved for use on California State highways where semi-permanent TL-3 barriers are required.

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Vehicle Crash Tests of the Aesthetic, See-Through Concrete
Bridge Rail with Sidewalk, Type 80SW

An aesthetic, see-through concrete bridge rail with sidewalk, Type 80SW, was built and tested in accordance with NCHRP Report 350. The barrier tested was 22.8 meters in length and was constructed at the Caltrans Dynamic Test Facility in West Sacramento, California.

Since this bridge rail is intended for pedestrian use and alone does not provide for pedestrian protection, it should only be used in low speed applications of 70 km/h or less. In addition, the handrail has been found to be a snagging hazard at the higher speed. For these two reasons, the Type 80SW is recommended for approval on California highways requiring TL-2 bridge rails.

The following research findings have been incorporated into Caltrans Standard Plans B11-62, B11-63, and B11-64.

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Crash Testing of Various Textured Barriers

Eight crash tests were conducted on seven different patterns of textured barriers. The test articles had the following textured surfaces: a deep cobblestone, a 19-mm deep fluted rib angled to 45 degrees, a "Mission Arch", a "Cobble Reveal", a Drystack stone, a Stone Ground Fractured Granite, and a Shallow Cobblestone. All test articles had a "base" profile similar to that of a Type 60 concrete barrier. All testing was completed under NCHRP Report 350 Test Level 3 guidelines.

The Mission Arch, Cobble Reveal, Drystack, and Stone Ground Fractured Granite textures as tested in the report are recommended for approval on California highways requiring TL-3 longitudinal barriers. The deep cobblestone, shallow cobblestone, and fluted ribs at a 45 degree are not recommended.

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Compliance Crash Testing of the Type 60K Concrete Barrier
Used in Semi-Permanent Installations

Three segmented, concrete barriers were built and crash tested in compliance with NCHRP Report 350. Each barrier was designed to match the single-slope profile of the California Type 60 median barrier. Of the three designs tested, only one meets the NCHRP 350 guidelines. The successful design (designated 60K-v3), consisting of 4-m long segments with pin-and-plate connections, demonstrated smooth redirection with minimal snagging potential.

Design 60K-v3 is recommended for operational use as a semi-permanent barrier.

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Vehicle Crash Tests of the Type 70 Bridge Rail

A bridge rail Type 70 was built and tested in accordance with NCHRP Report 350. The barrier tested was 22.9 meters long and was constructed at the Caltrans Dynamic Test Facility in West Sacramento, California. A total of four crash tests were conducted under Report 350 test Level 4.

The Type 70 is recommended for approval on California highways requiring TL4 bridge rails.

The following research findings have been incorporated into Caltrans Standard Plans B11-55, B11-56, and B11-57.

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Compliance Crash Testing of a Steel Version of the Type 732 Bridge Rail

A steel version of the Type 732 concrete bridge rail (Type 732S) was tested in accordance with NCHRP Report 350. The barrier tested was constructed off-site and later installed at the Caltrans Dynamic Test Facility in West Sacramento, California. The steel version is approximately 595 kg lighter per linear meter than the concrete version. This weight saving was critical to the design of the East span of the new San Francisco/Oakland Bay Bridge. Two crash tests were conducted under Report 350 test Level 4. The results of the two tests were within the limits of the Report 350 guidelines. The Type 732S bridge rail is recommended for approval on California highways requiring TL-4 bridge rails.

The following research findings have been incorporated into the project plans for the San Francisco/Oakland Bay Bridge East Span.

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Vehicular Crash Tests of a Slip-formed, Single Slope,
Concrete Median Barrier with Integral Concrete Glare Screen

Two single-slope concrete median barriers were built and crash tested. Construction was accomplished by a slip-forming method. Tests were performed in accordance with NCHRP Report 350 Test Level 3. A total of five crash tests were performed. Two tests were performed on a Texas barrier, two on a Type 60G barrier, and one on a Type 70 barrier.

The Type 60G barrier is recommended for approval on California highways. The following research findings have been incorporated into Caltrans Standard Plans A76A through A76I.


Impacts of Highway Culverts on Salmon and Steelhead

Impacts of Highway Culverts on Salmon and Steelhead

Salmon and steelhead are important resources for the people of California. Many salmon and steelhead populations are listed as threatened or endangered requiring protection under the Endangered Species Act. Nearly all of these fish must pass under roads of the state highway system to find the habitats they need for survival and successful reproduction. Improperly designed culverts at road crossings can prevent fish from reaching necessary habitat and cause declines in sensitive populations. The Culvert Survey Project is surveying state highway culverts in northwestern California. In the culvert survey project a number of problem culverts have been identified. The Division of Environmental Analysis and the Districts are already using the information database being developed in the culvert survey project. The knowledge generated from the test bed project will be used to design culverts and guide culvert installation.

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Urban Roads and the Endangered San Joaquin Kit Fox

Urban Roads and the Endangered San Joaquin Kit FoxThe San Joaquin kit fox (Vulpes macrotis mutica) is at risk of extinction primarily due to profound habitat degradation, fragmentation, and loss. However, kit foxes inhabit some urban areas, and roads present a potential threat to kit foxes in these areas. The effects of roads on urban kit foxes were investigated. Roads impact urban kit foxes through reduced survival, occasional den loss, inhibited movements, and habitat loss. When conducting road projects (e.g., construction, maintenance), Caltrans implements standard measures to minimize impacts to kit foxes. Implementation of additional measures, specifically the installation of artificial dens and road crossing structures, to further minimize impacts will facilitate conservation of urban kit foxes and contribute to range-wide recovery.