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Learn how to design work zones for speed, congestion, and delay management. Discover strategies to reduce traffic demands, improve flow, and enhance driver information. Explore the importance of enforcement and innovative technologies.
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Designing for Speed, Congestion, and Delay in the Work Zone Gerald Ullman Research Engineer Texas Transportation Institute
Work Zone Consequences • 40,000 injuries/year nationally • 120 workers killed annually • $4.5 billion/year national economic cost
Some other facts… • 43,500 miles of the National Highway System sees at least one day of work zone activity annually • In summer, we lose the equivalent of 41 million vehicles per day of roadway capacity due to work zones
Speed Management in Work Zones • Enforcement • Speed control technologies
Enforcement considerations • Realistic and “reasonable” speed limits • Adequate coordination between DOT and enforcement agencies • Labor availability
Enforcement • Circulating 2-3 mph • Stationary 3-13 mph • Police Traffic Controllers 2-14 mph • Operation Hardhat ???
Work Zone Speed Control Technologies • Enforcement surrogates • Driver information/feedback • Perceptual methods
Enforcement Surrogates • “Dummy” vehicles ----- • Unmanned radar 0-2 mph • Remote enforcement ----- • Automated enforcement -----
Driver Information/Feedback • Changeable Message Signs (CMS) 0-2 mph • CMS w/ radar 0-6 mph • Speed trailers 2-10 mph • CB Wizard 0-2 mph • Variable Speed Limits 0-5 mph*
Perceptual Methods • Rumble strips 1-6 mph • Transverse markings 0 mph • Narrowed lanes 0-8 mph
Congestion and Delay Management in Work Zones • Increase work zone capacity and efficiency of flow • Reduce traffic demands at work zone bottleneck points • Communicate accurate estimates of delay and congestion expectations
“Get In, Get Out, Stay Out” • 77% motorists prefer long-term repairs, even if delays are more significant • Focus on longer-lasting materials, better construction methods, longer service life horizon • Major constraint: $$
Increasing Capacity • Late-merge or dynamic merge control • Moveable barrier systems • Contractor accountability
Contractor Accountability • Arizona SR 68 (FHWA-HOP-04-032) • $400k incentive pool • Travel times exceeding 27 minutes reduced incentive pool
Reducing Traffic Demands • Working at night and weekends • Full roadway closures • Portable Intelligent Transportation System (ITS) technology
Concerns about Nightwork • Efficiency, quality of work • Safety • Traveling public • Workers • Worker quality of life
Full Roadway Closures • Roadway completely closed, traffic routed to alternative routes • Increases work efficiency • Eliminates traffic/work crew conflicts • Requires high degree of coordination and contingency planning • Impacts off-site difficult to predict and assess
Key principles • Motorists should not be told something they already know • Motorists should never be provided incorrect information (must maintain credibility) • Motorist diversion thresholds: 10-20 minutes delay