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12 22.4 percent in time during the afternoon peak period. Realign signal and relocate "Stop Ahead" sign to Between 2004 and 2005, the number of severe congestion improve visibility. hours was reduced by 37.7 percent (12). Detroit and Grand Rapids Low-Cost Improvement-- Syracuse, New York--Traffic signals were upgraded at American Automobile Association (AAA) Michigan ini- 145 locations with the following results: tiated a program to identify and treat locations in the 15.7 percent decrease in stops cities of Detroit and Grand Rapids with frequent crashes 16.7 percent reduction in travel time and congestion. Over the past six years, AAA Michigan 18.8 percent reduction in delay (9). examined 253 intersections and low-cost safety improve- It was found that the cost of optimizing traffic signals ments were implemented at 112 sites. Actions imple- ranges from $500 to $3,000 per intersection, while the bene- mented at the intersections included the following: fit to trucks moving within the City of Syracuse is likely val- Implementation of all-red intervals ued much greater on an annual basis. Replacement of 8-inch signal heads with 12-inch sig- Latham and Trombly (10) documented several examples nal heads of low-cost operational improvements that have potential Relocation of signal heads to improve visibility by to address mobility constraints. The following are a few realigning two signal heads facing each other, realign- examples: ing the signal heads over each lane of travel, or mount- Florida on US 1--by decreasing the number of median ing the signal heads using box span installations openings, fewer vehicles create slow-downs in left-lane Installation of secondary post-mounted signal heads traffic by exiting, entering, and even crossing traffic by to improve visibility at some locations use of a median. Such a change also likely has safety Installation of back plates on traffic signals to improve benefits for trucks as well. visibility at some locations Detroit, Michigan--an exclusive left-turn lane was added Installation of left-turn lanes through re-striping of at one intersection, along with other minor improve- approach lanes and exclusive left-turn phases, where ments including signal upgrades, at a cost of $36,100. Such needed an improvement has the potential to allow cars and trucks Removal of on-street parking. to turn left in a faster manner and may decrease traffic signal queues. 2.2.6 Low-Cost Regulatory/Public The City of Knoxville, Tennessee, Traffic Engineering Policy Improvements Department--has successfully implemented a number of low-cost traffic engineering improvements over the One approach to improve freight mobility with a low-cost years, e.g., focus involves changes in regulation. Adding new rules and Installing sight distance mirrors, where more expen- regulations governing the use of the freight transportation sive earthwork to remove the sight distance obstacle system may in turn decrease congestion, thereby improving is not feasible freight mobility. Regulatory changes and public policy-ori- Providing longer all-red intervals in the signal timing ented programs can be utilized to modify traveler behavior, where such things as bridge decks interfere with signals and thus mitigate freight mobility constraints. Most notably, Placing signal heads to provide a better view of red such programs and laws can address capacity issues that cause signals in locations with limited sight distance to sig- congestion by decreasing the annual vehicle miles traveled nal faces (VMT) of passenger vehicles, and thus increase the effective Providing narrower lane widths to provide additional "supply" of highway for use by freight operators. An exam- lanes ple of this is found in a GAO report (20), which cites several Providing detector-actuated flashers for sight distance public policy-based solutions to surface transportation problems that would require very expensive earthwork mobility constraints that could improve freight mobility, to correct. including using public information and programs to encour- The Public Works Department of the City of Spring- age the following: field, Missouri--installed and evaluated low-cost traffic engineering improvements to correct safety problems at Use of mass transit intersections. These treatments range in cost from $150 to Carpooling $5,000, e.g., Teleworking. Install mast arm to mount signal heads overhead to improve visibility From a public-sector position, such programs are low cost Install lane use signs and quickly implementable, especially in comparison to multi-