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NCHRP 3-74 Chapter 4 Selection of Speed Reduction Treatments at High-Speed Intersections Treatment Installations Page 4-1 4 Treatment Installations Once the before testing was completed, the research team coordinated with each agency to install treatments at each of the testing sites. Due to the three-month acclimation period, installing the treatments in a timely manner was a high priority to meet the overall project timeline. As shown previously, Exhibit 3-30 summarizes the testing and installation dates of each treatment. Most participating agencies desired treatments that were inexpensive, easy to install, and did not required extensive maintenance. Therefore, in most cases the installation process for each treatment was completed in one day by agency staff. The transverse pavement markings and rumble strip installations required little time to install. The agencies had the materials in stock and there were not utility impacts. In these cases, the roadway maintenance crews for each agency obtained the material and installed the treatment at the specified location within a few hours. As shown previously in Exhibit 3-30, Clackamas County was able to install transverse pavement markings at four locations in the same day. ODOT and TXDOT were also able to install the transverse pavement markings and rumble strips, respectively, within one day. The dynamic warning sign installations required more coordination for the agencies due to the sign purchasing and designing, selecting the detection type (i.e. radar or loop detectors), and accessing a power source. The dynamic warning sign installations required power sources to provide power to the electronic sign. Therefore, TXDOT and WSDOT coordinated with the utilities and power in the site vicinity to identify the most appropriate and convenient power source. The following exhibits illustrate photos of each treatment installed in Oregon, Washington, and Texas. 4.1 CLACKAMAS COUNTY 1.) Whiskey Hill Road/Meridian Road Exhibit 4-1 Eastbound on Whiskey Hill Road
Chapter 4 NCHRP 3-74 Treatment Installations Selection of Speed Reduction Treatments at High-Speed Intersections Page 4-2 Exhibit 4-2 Northbound on Meridian Road 2.) Canby-Marquam Highway/Lone Elder Road Exhibit 4-3 Southbound on Canby-Marquam Highway Exhibit 4-4 Northbound on Canby-Marquam Highway
NCHRP 3-74 Chapter 4 Selection of Speed Reduction Treatments at High-Speed Intersections Treatment Installations Page 4-3 3.) Redland Road/Ferguson Road Exhibit 4-5 Eastbound on Redland Road Exhibit 4-6 Westbound on Redland Road 4.) Redland Road/Bradley Road Exhibit 4-7 Eastbound on Redland Road The transverse pavement markings in Clackamas County were installed with thermoplastic material. After the research team reviewed the treatment installations at these locations, there were two items noted for future consideration which include marking location and visibility. As shown in the above exhibits, at all of the sites, there were treatments installed downstream of
Chapter 4 NCHRP 3-74 Treatment Installations Selection of Speed Reduction Treatments at High-Speed Intersections Page 4-4 existing signs. The intent of these particular treatment locations were to supplement the existing signing by providing an additional visual cue that the roadway segment was changing and an intersection is ahead. Therefore, in the future the research team would instruct the agency to install the treatments upstream of the existing signs. This would allow a driver to observe the visual treatment prior to observing the Âintersection ahead or other warning sign. Instead, the way the treatments are currently shown may actually distract the driver away from the existing sign by directing their eyes downstream at the markings. In addition to the marking location upstream of the sign, the research team would also recommend using a more visible pavement marking design. The marking design is based on the existing lane width and the width of the design vehicle wheel base. Due to the narrow lane widths and high volume of truck traffic on the rural two-lane roadways in Clackamas County, the pavement markings shown are approximately 12 inches in length and 8 inches in width. In the future, the research team would recommend extending the pavement marking farther (approximately 18 to 24 inches) into the travel lane and using a pavement marking width of approximately 12 to 18 inches. This would provide a more significant visual treatment and allow drivers to observe the treatment from farther distances. 4.2 OREGON DEPARTMENT OF TRANSPORTATION 5.) OR 6/Wilson River Loop Exhibit 4-8 Westbound on OR 6 The transverse pavement markings in Tillamook, Oregon were installed with paint. ODOT chose to install the pavement markings as an interim treatment before constructing a future interchange at this location. Therefore, they chose to use material that was less expensive and easier to remove from the pavement. As shown in the above exhibit, the treatments were installed upstream of the existing sign, as recommended by the research team. However, similar to the transverse pavement marking location in Clackamas County, the research team would also recommend using a more visible pavement marking design that would extend farther into the travelway.
NCHRP 3-74 Chapter 4 Selection of Speed Reduction Treatments at High-Speed Intersections Treatment Installations Page 4-5 4.3 WASHINGTON DEPARTMENT OF TRANSPORTATION 6.) SR 26/SR 24/1st Street Exhibit 4-9 Eastbound on SR 26 Exhibit 4-10 Westbound on SR 26 WSDOT chose to design a specific sign for the Othello, Washington site, which required the agency to develop design plans and decide on the type of dynamic message to install. As shown in Exhibit 4-9 and 4-10, this sign included a static Âspeed limit and Âintersection ahead sign combined with a dynamic sign that would flash Âslow and Âdown when triggered by specific vehicle speeds. WSDOT constructed the static sign board and base, however, the dynamic warning sign and radar was purchased from an outside vendor. Due to the time required for ordering and receiving the dynamic sign and radar, the static sign was installed for a short period of time before the dynamic sign and radar was received and installed.
Chapter 4 NCHRP 3-74 Treatment Installations Selection of Speed Reduction Treatments at High-Speed Intersections Page 4-6 Kittelson & Associates, Inc. 4.4 TEXAS DEPARTMENT OF TRANSPORTATION 7.) US 82/SH 98 Exhibit 4-11 Westbound on US 82 For the dynamic warning sign installation in Texas, TXDOT used a standard sign and layout for the treatment installation. Therefore, this required less time for designing and obtaining the sign. As shown in Exhibit 4-11, this sign included a speed limit sign and a dynamic sign below that would show the speed of each passing vehicle. 8.) US 271/FM 726 Exhibit 4-12 Southbound on US 271 Exhibit 4-13 Southbound on US 271
NCHRP 3-74 Chapter 4 Selection of Speed Reduction Treatments at High-Speed Intersections Treatment Installations Kittelson& Associates, Inc. Page 4-7 9.) US 271/FM 593 Exhibit 4-14 Southbound on US 271 Exhibit 4-15 Northbound on US 271 10.) US 271/FM 2088 Exhibit 4-16 Northbound on US 271 Exhibit 4-17 Northbound on US 271
Chapter 4 NCHRP 3-74 Treatment Installations Selection of Speed Reduction Treatments at High-Speed Intersections Page 4-8 Kittelson & Associates, Inc. Exhibit 4-18 Southbound on US 271 As shown in the above exhibits, the rumble strips installed in Texas were installed in two transverse segments in the wheel path of the travel way. The rumble strips consisted of a white plastic material that was adhered to the pavement. Therefore, in addition to the audible and physical vibration of the strips this was also a visual treatment. As shown in Exhibit 4-12 and 4-18, at some of the locations there was an existing pavement marking legend that illustrated the speed limit of the roadway. In reviewing the treatment installation locations, the research team recommends installing the rumble strips upstream of the existing pavement legend, as shown in Exhibit 18. Similar to the discussions with the transverse pavement markings, installing the rumble strips upstream of the existing markings allows drivers to become more alert from the rumble strips and then more likely to notice the additional speed limit pavement markings. If the rumble strips are installed downstream of the existing pavement markings, the driver may not become aware of the intersection until after experiencing the rumble strips, at which time they have already passed the other pavement markings to illustrate the speed limit. 4.5 SUMMARY All of the treatments were installed in a timely manner allowing the research team to maintain the project timeline. After the treatment installation the research team did identify some treatment locations and designs that could have been improved. However, the research team is confident that the treatment installations and designs shown provided an appropriate basis for measuring the effectiveness of each treatment type.
