U.S. Department of Transportation
Federal Highway Administration
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Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: FHWA-HRT-10-004 Date: May/June 2010|
Publication Number: FHWA-HRT-10-004
Issue No: Vol. 73 No. 6
Date: May/June 2010
Below are brief descriptions of communications products recently developed by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. All of the reports are or will soon be available from the National Technical Information Service (NTIS). In some cases, limited copies of the communications products are available from FHWA's Research and Technology (R&T) Product Distribution Center (PDC).
When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Toll-free number: 800-553-NTIS (6847)
Web site: www.ntis.gov
Requests for items available from the R&T Product Distribution Center should be addressed to:
R&T Product Distribution Center
Szanca Solutions/FHWA PDC
13710 Dunnings Highway
Claysburg, PA 16625
For more information on R&T communications products available from FHWA, visit FHWA's Web site at www.fhwa.dot.gov, the Turner-Fairbank Highway Research Center's Web site at www.tfhrc.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.
Design and Evaluation of Jointed Plain Concrete Pavement With Fiber Reinforced Polymer Dowels
Publication No. FHWA-HRT-06-106
Highway departments commonly use steel dowel bars as load transferring devices in concrete pavement, but these bars can cause corrosion and loosening of the connection between the dowel and the pavement, among other issues. This study evaluates fiber reinforced polymer (FRP) dowel bars as an alternative to steel in jointed plain concrete pavement (JPCP) under the American Association of State Highway and Transportation Officials' (AASHTO) HS-25 static and fatigue wheel loads and compares their response with JPCP using steel dowels.
The report, Design and Evaluation of Jointed Plain Concrete Pavement with Fiber Reinforced Polymer Dowels, details laboratory and field evaluations of JPCP with FRP and steel dowels, analytical modeling of dowel response, and field rehabilitation of JPCP using FRP dowels. Researchers collected field data through an automatic data acquisition system, which captured strain and joint deflections used for assessing joint load transfer efficiency (LTE), joint relative deflection, and pavement performance. The report provides theoretical calculations through different examples for JPCP with FRP and steel dowels by varying dowel diameters, spacing, dowel material properties, joint width, and base material properties.
In conclusion, the study found that JPCP with FRP dowels provides ample LTE up to and beyond 90 percent, which exceeds criteria set by AASHTO and the American Concrete Pavement Association. JPCP with
FRP dowels also has proven to hold up in the long term, providing sufficient LTE after 5 million cycles of fatigue tests under HS-25 loading.
Printed copies of the report are available from the PDC.
Time-Frequency Analysis: Mathematical Analysis of The Empirical Mode Decomposition (Fact Sheet)
Publication No. FHWA-HRT-10-029
Mathematical Analysis of the Empirical Mode Decomposition is a 3-year study sponsored by the FHWA Exploratory Advanced Research Program and awarded to Princeton University to develop a mathematical foundation for empirical mode decomposition (EMD). Invented more than 10 years ago, EMD provides a nonlinear time-frequency analysis with the ability to evaluate nonstationary signals. Transportation-related applications of EMD could include detecting early signs of fatigue in vibrating metal components and locating cracks or loss of rigidity in reinforced bridge columns. This fact sheet discusses EMD's origins, mathematical challenges, and potential benefits to the transportation industry.
Over the past decade, EMD has been used in a wide range of fields, including biology, geophysics, ocean research, radar, and medicine. Although researchers have fine-tuned the algorithm and extended it to a variety of different applications, little is known about EMD's mathematical properties. This research, therefore, aims to explore the theoretical foundations of this empirical tool and develop new software tailored to specific applications.
The fact sheet is available at www.fhwa.dot.gov/advancedresearch/pubs/10029/index.cfm. Printed copies are available from the PDC.
Double Crossover Diamond Interchange (TechBrief)
Publication No. FHWA-HRT-09-054
Today's traffic volumes and travel demands often lead to safety problems that are too complex for conventional intersection designs to handle properly. Consequently, FHWA released Alternative Intersections/Interchanges: Information Report (AIIR) (FHWA-HRT-09-060), which highlights four alternative intersection designs and two interchange designs that offer substantial advantages over conventional at-grade intersections and grade-separated diamond interchanges. This TechBrief summarizes information on one of the alternative interchange designs, the double crossover diamond (DCD) interchange.
The DCD interchange, also known as a diverging diamond interchange, is a new interchange design that is similar to the design of a conventional diamond inter--change. The main difference is the way left and through movements navigate between the cross street intersections with ramps. The DCD design accommodates left-turning movements onto arterials and limited-access highways while eliminating the need for a left-turn signal phase at signalized ramp terminal intersections. On the cross street, the traffic moves to the left side of the roadway between the signalized ramp intersections. Drivers on the cross street who want to turn left onto the ramps can continue do so without conflicting with opposing through traffic and without stopping. The DCD interchange offers benefits over conventional interchange designs, including lower costs, fewer conflict points, increased throughputs, reduced delays, decreased speeds, and reduced environmental impacts.
The document is available at www.fhwa.dot.gov/publications/research/safety/09054/index.cfm. Printed copies are available from the PDC.
Displaced Left-Turn Intersection (TechBrief)
Publication No. FHWA-HRT-09-055
This TechBrief summarizes information on the displaced left-turn (DLT) intersection, one of the alternative intersection designs featured in the FHWA report Alternative Intersections/Interchanges: Information Report (AIIR) (FHWA-HRT-09-060).
The DLT intersection, also known as the continuous flow intersection or the crossover displaced left-turn intersection, moves left-turn movements from the main intersection to an upstream signalized location. Traffic that would turn left at the main intersection in a conventional design now must cross opposing through lanes at a signal-controlled intersection several hundred feet upstream and then travel on a new roadway parallel to the opposing lanes. From this new roadway, the left-turning traffic executes the left turn onto the perpendicular roadway simultaneously with the through traffic at the main intersection. Traffic signals at the left-turn crossovers and the main intersection are operated in a coordinated mode so vehicles do not stop multiple times in the intersection area. The primary benefit of the DLT intersection is the reduction in the number of traffic signal phases and conflict points with consequent improvements in operations and safety.
The document is available at www.fhwa.dot.gov/publications/research/safety/09055/index.cfm. Printed copies are available from the PDC.
Displaced Left-Turn Interchange (TechBrief)
Publication No. FHWA-HRT-09-056
This TechBrief summarizes information on the displaced left-turn (DLT) interchange, the other alternative interchange design featured in the FHWA report Alternative Intersections/Interchanges: Information Report (AIIR) (FHWA-HRT-09-060).
The DLT interchange design has similarities to both the at-grade DLT intersection and the double crossover diamond interchange. The main feature of the DLT interchange is that left-turning traffic crosses opposing through lanes several hundred feet upstream of the main intersection and then proceeds on a new roadway situated between the opposing through lanes and a roadway that carries right-turning traffic from the ramp. From this new roadway, the left-turning traffic completes its maneuver onto the on-ramp. The DLT interchange offers benefits over a conventional diamond interchange with its efficient and simplified two-phase operation that typically results in increased capacity, reduced delays, and separated conflict points.
The document is available at www.fhwa.dot.gov/publications/research/safety/09056/index.cfm. Printed copies are available from the PDC.
Median U-Turn Intersection (TechBrief)
Publication No. FHWA-HRT-09-057
This TechBrief summarizes information on the median U-turn (MUT) intersection, another one of the alternative intersection designs featured in the FHWA report Alternative Intersections/Interchanges: Information Report (AIIR) (FHWA-HRT-09-060).
Roadway designers can implement MUT intersections as either full MUTs -- where direct left turns from both the major and minor approaches are eliminated from the main intersection -- or as partial MUTs -- where direct left turns from only the major approaches are eliminated. On the major road, drivers who want to turn left must travel straight through the at-grade main intersection, make a U-turn at the median opening downstream of the intersection, and then turn right onto the cross street. On the minor street, drivers who want to turn left onto the major road must turn right at the main intersection, execute a U-turn at a downstream median opening, and proceed straight through the main intersection. The benefits of the MUT intersection include increased capacity and safety.
The document is available at www.fhwa.dot.gov/publications/research/safety/09057/index.cfm. Printed copies are available from the PDC.
Quadrant Roadway Intersection (TechBrief)
Publication No. FHWA-HRT-09-058
This TechBrief summarizes information on the quadrant roadway (QR) intersection, another one of the alternative intersection designs featured in the FHWA report Alternative Intersections/Interchanges: Information Report (AIIR) (FHWA-HRT-09-060).
A QR intersection works by rerouting all four left-turn movements at a four-legged intersection onto a road that connects the two intersecting roads. The location of the connector road depends on traffic flow and availability of right-of-way. All four of the left-turning movements are rerouted over the connector road. This design prohibits all left turns at the main intersection and therefore allows a simple two-phase signal to process the remaining through and right-turn movements. The QR intersection increases operational efficiency through a congested intersection by moving the left turns away from the main intersection.
The document is available at www.fhwa.dot.gov/publications/research/safety/09058/index.cfm. Printed copies are available from the PDC.
Restricted Crossing U-Turn Intersection (TechBrief)
Publication No. FHWA-HRT-09-059
This TechBrief summarizes information on the restricted crossing U-turn (RCUT) intersection, another one of the alternative intersection designs featured in the FHWA report Alternative Intersections/Interchanges: Information Report (AIIR) (FHWA-HRT-09-060).
The RCUT intersection, also referred to as the superstreet intersection or J-turn intersection, is characterized by the prohibition of left-turn and through movements from side street approaches. Instead, the RCUT intersection accommodates these movements by requiring drivers to turn right onto the main road and then make a U-turn maneuver at a one-way median opening 400-1,000 feet (122-305 meters) after the intersection. Drivers execute left turns from the main road approaches in a manner similar to left turns at conventional intersections. The benefit of the RCUT intersection is that it reroutes minor street left-turn and through movements to a median U-turn crossover, which provides major advantages such as reduced delay and congestion for through traffic on the major road and reduced opportunities for crashes compared to conventional designs.
The document is available at www.fhwa.dot.gov/publications/research/safety/09059/index.cfm. Printed copies are available from the PDC.