The National Academies Press

Currently Skimming:

Pages 36-83

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 36... ... 36 Information on current organizational practices regarding 1L2W operations at rural highway TTC zones was obtained using a survey questionnaire. This chapter summarizes the findings from the survey questionnaire and follow-up telephone interviews and explains organizations' practices, perspectives, and experiences with 1L2W operations. Read the entire page →
From page 37... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 37 Survey questionnaire responses were analyzed, and documents obtained from responding organizations including typical applications, standards, guidelines, and manuals were reviewed. The rest of this chapter presents the findings with respect to traffic analysis, design thresholds, methods, side road and driveway treatment, end-of-queue management, mandatory use of PCMSs, and project coordination in 1L2W TTC zones. Read the entire page →
From page 38... ... 38 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway allows design engineers to evaluate mobility impacts using Synchro micro-simulation, graphs, or a software tool called Construction, Congestion, Cost (CO3) Read the entire page →
From page 39... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 39 WZTA is shown in Figure 3-4. To determine lane closure restrictions, capacity of the road segment and expected demand are determined. Read the entire page →
From page 40... ... 40 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Figure 3-4. A screenshot of the web-based TTC zone traffic analysis tool (Toews and Jackson 2008) Read the entire page →
From page 41... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 41 Design Thresholds State DOTs use different design criteria for selecting traffic control methods in 1L2W operations. These design criteria commonly include length of closure, vehicle delay, traffic volumes, and speed. Read the entire page →
From page 42... ... 42 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway South Dakota Self Managed: 600 feet 15 Texas Self Managed: 400 feet Self Managed: 2,000 Vermont 1,000–2,500 feet 10 Virginia 2 miles AFADs: 800 feet Flag Transfer: 1 mile 10 (> 500 vpd) Read the entire page →
From page 43... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 43 Maximum allowable vehicle delays vary between 5 and 30 minutes. Speed limit is also considered in selecting proper 1L2W methods. Read the entire page →
From page 44... ... 44 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Flagger stations need to be placed at locations that provide safe operations. For example, several state DOTs, such as the Arizona Department of Transportation (ADOT) Read the entire page →
From page 45... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 45 stops the traffic approaching in the closed lane. Traffic in the opposite direction flows free. Read the entire page →
From page 46... ... 46 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway • VDOT allows usage of a single flagger for 1L2W traffic control when length of closure is short, sufficient sight distance is available, and traffic volumes are less than 500 vpd. Shadow vehicles are used in the human flagger control method. Read the entire page →
From page 47... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 47 Many state DOTs -- including Kansas (KDOT 2015a) , Maine (Maine DOT 2014) Read the entire page →
From page 48... ... 48 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Night Flagging The MUTCD states that flagger stations shall be illuminated when nighttime flagging is performed (FHWA 2009) Read the entire page →
From page 49... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 49 flaggers. These roads often have horizontal or vertical curvilinear geometries. Read the entire page →
From page 50... ... 50 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway The MUTCD requires that this method be employed only when the one-lane section is relatively short, usually less than one mile in length (FHWA 2009) Read the entire page →
From page 51... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 51 • In Missouri, MoDOT utilizes self-managed control when all of the following conditions exist (MoDOT 2017) Read the entire page →
From page 52... ... 52 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Notes: 1. Approach signs are the same in both directions. Read the entire page →
From page 53... ... Note: 1. S and B distances are listed in Table 3-9. Read the entire page →
From page 54... ... 54 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway • PennDOT has provided typical applications for self-managed stop control in short-term stationary (see Figure 3-13) and long-term stationary (see Figure 3-14) Read the entire page →
From page 55... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 55 Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 56... ... Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 57... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 57 Speed (mph) Read the entire page →
From page 58... ... 58 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Notes: 1. Buffer lengths are listed in Table 3-11. Read the entire page →
From page 59... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 59 • KDOT allows a single flagger to operate two AFADs when (KDOT 2015a) Read the entire page →
From page 60... ... 60 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Notes: 1. Approach signs are the same in both directions. Read the entire page →
From page 61... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 61 AFADs. State DOTs have developed or are developing standard plans and guidelines for the use of AFADs. Read the entire page →
From page 62... ... Figure 3-19. Florida typical application for TTCSs (FDOT 2017b) Read the entire page →
From page 63... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 63 actuation," the right-of-way indication dwells in All-Red when there are no detected vehicles or recall switches. If an additional phase is utilized for a side road movement, there should be one long All-Red interval between active phases on each side of the work area. Read the entire page →
From page 64... ... 64 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Note: 1. S and B distances are listed in Table 3-13. Read the entire page →
From page 65... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 65 Note: 1. S and B distances are listed in Table 3-13. Read the entire page →
From page 66... ... 66 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Length (feet) Minimum All-Red interval (sec) Read the entire page →
From page 67... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 67 Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 69... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 69 Note: 1. Optional signal configurations shall only be used when the primary configuration is unreasonable due to physical obstructions. Read the entire page →
From page 70... ... Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 71... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 71 Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 72... ... 72 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Figure 3-27. Pilot car method deployment in 1L2W operations by state DOTs. Read the entire page →
From page 73... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 73 Notes: 1. A, B, and C distances are listed in Table 3-16. Read the entire page →
From page 74... ... 74 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway • The Nebraska DOT requires pilot cars to make a round trip in 15 minutes or less (NDOR 2007) Read the entire page →
From page 75... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 75 should be placed at all intersections, driveways, and alleys. The supplementary sign is not a standard MUTCD sign, and it is not included in the MUTCD. Read the entire page →
From page 76... ... Figure 3-29. Florida typical applications for side road treatment (FDOT 2017a) Read the entire page →
From page 77... ... Notes: 1. Sign spacing (X) Read the entire page →
From page 78... ... 78 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway End-of-Queue Management End-of-queue management is primarily performed using additional advance signs or increasing sign spacing. When traffic queues extend beyond initial advance warning signs, extended queue signing is utilized in states including California, Oregon (ODOT 2016a) Read the entire page →
From page 79... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 79 For projects in close proximity, California requires a dedicated Traffic Manager to be assigned to coordinate the closures to maximize throughput and minimize traffic delays. Vermont and Georgia DOTs require the distance between consecutive lane closures to be at least 1 mile (VTrans 2011, GDOT 2012) Read the entire page →
From page 80... ... 80 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 81... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 81 Notes: 1. For rural roadways, suggested spacing of advance warning signs (A, B, and C) Read the entire page →
From page 82... ... 82 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway In the typical applications, a flagger is stationed at the center of the intersection. It is stated that each flagger shall be clearly visible for a minimum distance of E (see Table 3-10) Read the entire page →
From page 83... ... Survey Questionnaire and Interview Summary: An Overview of the Current State of Practice 83 Survey questionnaire results indicated that human flagger control is the most common traffic control method utilized in 1L2W operations among the state DOTs, while advance flaggers, flag transfer, self-managed, and AFADs are not frequently utilized. Pilot cars and TTCSs are commonly used by state DOTs. Read the entire page →

From page 36...

... 36 Information on current organizational practices regarding 1L2W operations at rural highway TTC zones was obtained using a survey questionnaire. This chapter summarizes the findings from the survey questionnaire and follow-up telephone interviews and explains organizations' practices, perspectives, and experiences with 1L2W operations.