Objectives • Describe a maintenance of traffic plan for a roadway project • Define work zone problems and reasons for same • Identify work zone traffic control devices • Present details of work zone traffic control
http://mutcd.fhwa.dot.gov/ - contains standards and principles for design, installation, and maintenance of traffic control devices in work zones. Direct link to pdf version: http://mutcd.fhwa.dot.gov/pdfs/2003r1/pdf-index.htm Key resources … http://wzsafety.tamu.edu/ AASHTO Roadside Design Guide: Chapter 9 discusses: Traffic Barriers, Traffic Control Devices and Other Features in Work Zones. Should be used with Traffic Control Devices Handbook – Part VI http://safety.fhwa.dot.gov/fourthlevel/pdf/bestprac.pdf
Maintenance of Traffic Plans (MOT) or Traffic Control Plans (TCP) • A plan directed to the safe and expeditious movement of traffic through construction and to the safety of the work force performing those operations • How/when traffic is maintained during construction • Typically required … always needed • Often not given proper time or attention – switching time most dangerous http://www.fhwa.dot.gov/tfhrc/safety/pubs/89035/89035.pdf
Plan Components • Pavement marking, cones, barriers for channelization • Illumination and warning lights (steady for path, flashing for single points) • Policies for removal of signs, etc. • Staging of Traffic (how it flows) • Need for flaggers, etc. • Notes (e.g, move or sign all equipment when not in operation in the work zone) • No parking of employee cars in work zone • Cost estimate must include labor, signs, cones, etc. • Include the following (if needed): • Diversion/detour alignments • Tapers and lane drops (see MUTCD) • Pedestrian accommodations • Traffic control (signals, sign type, sign location)
This page includes links to databases and web sites of standards, specifications, and practices that are related to work zone safety. Work Zone Safety Standards and Practices DatabaseManual on Uniform Traffic Control Devices (MUTCD) Visibility and Retroreflectivity RelatedOSHA RegulationsBest Practices on Work Zone SafetyFHWA's National Highway SpecificationsFHWA's Work Zone Mobility and Safety Fact SheetsWork Zone Traffic Control Inspection Forms http://wzsafety.tamu.edu/files/S&P.stm
Special conditions in TCP • High volume or high speed traffic. • Rush hour or seasonal traffic patterns. • Heavy use by pedestrians. • Changing work conditions or other conditions that would be confusing to the traveling public. • Hazards due to nighttime operations. • Complex detours or traffic patterns. • Closely spaced intersections, interchanges, or other decision points.
Checklist of factors • Estimated traffic volumes, vehicle types, and direction of travel. • Traffic speeds. • Required number of travel lanes. • Traffic control layouts including signing, markings, channelization devices, traffic signals, traffic • delineators, barriers, and detour schemes. • Restrictions on work periods such as rush hours, holidays, special events, nights, weekends. • Characteristics of adjacent highway segments. • Requirements for partial completion and opening sections to traffic. • Maneuvering space available for traffic. • Requirements for installing, maintaining, moving, or removing traffic control devices. • Turns or cross movements required by traffic.
Additional Considerations(but not in contract) • The need for public relations, such as notifications to the local news media. • Any special agreements reached with other agencies relating to traffic control or traffic management. • Accident reporting requirements. • Any special guidance on traffic management for the project engineer.
Why are Work Zones more Prone to Crashes? • Why are work zones difficult for drivers and subsequently dangerous for workers? • Violate – Expectancy • Increased – Workload • Combine – Both
Work Zone Safety Facts • Late 90s … ~700 deaths/year … 1074 in 2005! • Tractor/trailer involvement in work zones crashes are high (26% of fatalities) • Work Zone crashes generally more severe (more injuries/fatalities than national average)- Fixed object impacts result in more injuries/fatalities than vehicle to vehicle impacts • ½ of work zone fixed object impacts occur at night (impact on staging??)
Work Zone Safety Facts • 1994-98 Average was that 16% of work zone fatalities were peds/bicyclists • Fatal work zone crashes are twice as high as non-work zone fatals on urban interstates (14% are FATAL!) • The majority of fatal work zone crashes occur on 55 mph or greater speed limits (No need for slow speed MOT? Ped/bike/ car fatalities? – increase over 35 mph but occur much lower) • 29% of fatals on weekends! (most in summer and fall) • ~150 workers killed each year (who are the workers???) Utility work in bike lanes can often be accomplished without blocking the entire lane. http://safety.fhwa.dot.gov/ped_bike/univcourse/swless12.htm
Work Zone Traffic Control Devices • Cones/Tubular Markers • Vertical Panels • Drums (watch breakaway lamps – ballast at bottom and no greater than 25 kg) • Barricades Type I, II, and III • Shadow Trucks, etc. for moving construction or maintenance
Temporary barriers - Portable Concrete Barrier (PCB) http://tti.tamu.edu/documents/0-4692-1.pdf TTI study of portable concrete barrier design
617.1.5 Temporary Glare Screens. Temporary glare screens in work zones consist of modular units installed on top of temporary concrete traffic barrier. Temporary glare screens prevent headlight glare. Glare screens may also be used to block the driver’s view of construction activities. Glare screens are not used where they could restrict driver visibility and sight distance. Use of these units are limited due to installation and maintenance concerns to areas where work zone activities could impact the flow of traffic, or geometrics could create a blinding effect on drivers. When specified, quantities are calculated and shown on the plans. - MODOT Glare screen should not be installed in medians wider than 6.1 m. -CalTrans Transpo Industries web site
BMW Takes On Glare Screen WSDOT's IRT member Don Harris said the weekend accident on westbound SR 520 near 92nd Avenue was one of the more unusual situations to which he’d responded. The driver of a BMW lost control and drove for 780 feet on the jersey barrier, taking out 640 feet of glare screens. The screens are on top of the jersey barrier to prevent the headlights of opposing traffic from blinding or distracting drivers. Harris’s job was to pick up all those glare screens while WSP Troopers took custody of the driver. Traffic was up and running again shortly after the 8:15 a.m. accident.
Detour considerations • Speed • Capacity • Distance • Safety
How to increase detour capacity (e.g., during I-235 reconstructions – Univ. Ave., etc.) • eliminate some turns • reroute some trucks and buses • ban parking • ban loading/unloading during peak • eliminate some bus stops • coordinate signals • widen the traffic way • implement one-way • ITS??? (incident management, esp.)
Specifics for Work Zones • Fundamental principles of work zone traffic control design • Four work zone areas and their components • Taper lengths and types • Advance signing applications and factors that impact setup
Work Zone Traffic Control Design – 10 Fundamental Principles (MUTCD Part 6) Why? worker/motor vehicle safety in temporary traffic control areas • Traffic safety must be integral and high-priority during project development (from planning to construction) and rehab/ maintenance or utility activities • Follow same principles of normal permanent roadside/roadway designs (goal is use comparable geometrics/traffic control if possible)
Fundamental Principles (cont.) • Produce a traffic control plan (TCP) (understand before field work) • Traffic should be inhibited as little as practicable • Avoid frequent and abrupt geometry changes • Provide for incident management vehicles • Minimize work time and do off-peak if possible • Guide drivers/peds in a clear and positive manner approaching and through zone (adequate traffic control, proper action with permanent control, flagging)
Fundamental Principles (cont.) • Routinely inspect your traffic control elements • Maintain the roadside during construction (for safety) • Train all levels of workers in temporary traffic control zone safety • Provide statutes that allow work zone traffic control (no real engineer control???) • Maintain good public relations (media)
Activity Area Storage (not shown) 4. Termination Area – returns traffic to normal Work 3. Activity Area – where the work happens Buffer 2. Transition Area – channels the traffic Traffic 1. Advance Warning - what to expect