The Future Is Now
TRB 2005, Session 628
Ohio Department of Transportation
PDF Version (400 kb)
Work Zone Impacts
There is a link between capacity and crashes.
- 43% of all Ohio IR crashes occur on 12% of our IR system
- Of this 12%, virtually all of it is over capacity
- What does this have to do with work zones you ask?
Work Zone Impacts - Capacity
- Thanks for asking
- Work zones by their very nature reduce capacity
- Exceeding capacity causes crashes
- Work zone conditions can exasperate crashes (narrow lanes, clear zone issues, etc.)
Plan to Address WZ Capacity/Crashes
- Developed "Maintenance of Traffic Policy" to ensure satisfactory WZ capacity - 2000
- Developed MOT Alternative Analysis (MOTAA) to identify WZ "constraints" early in project development - 2003
- Developed process to monitor WZ crashes in near real-time - 2004
Plan to Address WZ Capacity/Crashes
- Maintenance of Traffic Policy = Proactive
- Maintenance of Traffic Alternative Analysis = Proactive
- Work Zone Crash Reporting = Reactive
The Policy Process
The ODOT MOT Policy
- Established "Permitted Lane Closures (PLC)"
- Hours each individual IR segment can have a lane reduction based on capacity
- PLC times applicable to both maintenance and construction projects
- Established maximum allowable queue impacts
- Allowable queue thresholds
- Queues less than 0.75 miles are acceptable
- Queues greater than 0.75 miles and less than 1.5 miles if the queue exceeds 0.75 for two hours or less
- 0.75 mile queues with a duration greater than 2 hours or longer than 1.5 miles are unacceptable
- Established analysis process to determine queue impacts of projects that violate PLC
- Utilize Quez98 program/ODOT spreadsheet/adjustment factors to predict queues
- Established exception process that requires analysis of cost, schedule, queue impacts for numerous alternatives
- Final decision is by executive committee (due to financial ramifications)
- Net results
- Much more off peak hours and night time work (maintenance and resurfacing projects)
- Spending $$$$$ to provide sufficient capacity in big projects
- Systematic planning to provide sufficient work zone capacity
The MOT Alternatives Analysis
ODOT MOT Alternatives Analysis
- What is it?
- Analysis of potential work zone impacts "constraints" that occurs PRIOR to the first detail plan submissions
- It occurs early enough so that MOT can be used to:
- Pick between feasible project alternatives
- Size structure widths
- Highlight WZ right-of-way and environmental impacts early enough to do something about them
The ODOT MOTAA
- Designer is given a specific "desired" foot print (cross section) and then reports on a given list of potential problems
- The number of lanes are based on the PLC
- "Desired" foot print (cross section) is overlaid at defined location for both a crossover and part width alternatives.
- Designer reports (for both crossovers and width) if any of the following problems would be expected:
- Work zone policy
- Maintain access (off-ramp capacity)
- Ramp merges
- Environmental impacts
- Construction cost/duration
- Maintenance of existing lighting/drainage
- Construction joint location (concrete)
- Crossover location
- R/W impacts
- Bridge widths
- Earthwork, retaining walls, profiles
- Constructability / Constr. Access
- Provide "desirable" "footprint/cross section"
|Factor to be considered||Option|
Part-Width Construction (with partial demolition at bridges)
X-over Construction (without partial demolition at bridges
- OSE has indicated that partial demolition will provide acceptable factors of safety for a temporary condition. The cost for temporary demolition assumes that temporary piles and shoring of the existing bridge structures will not be required.
- Assume $1.0M base cost for MOT, plus additional MOT related items as identified in the chart above. This chart summarizes costs for the BUT-WAR-63 project, only.
|Ability To Meet Work Zone Policy||Full closure of I-75 may be required at night, during partial demolition of the structure.||Meets policy at all times.|
|Ability To Maintain All Accesses||Simple access provided, utilizing two-step construction.||Access to SR-63 will be provided using crossovers in Stage 3.|
|Ability To Provide On-Ramp Decision Sight Distances||Meets TEM requirements.||Meets TEM requirements. See strip maps, Exhibits A through G.|
|Right-Of-Way And Environment Impacts||MOT scheme would not increase R/W or environmental impacts along I-75. Additional (minor) temporary easements are anticipated along SR-63, to facilitate placement of temporary pavement for part-width construction.||MOT scheme would not increase R/W or environmental impacts along I-75. Additional (minor) temporary easements are anticipated along SR-63, to facilitate placement of temporary pavement for part-width construction.|
|Final Bridge Widths||MOT scheme does not impact proposed final bridge widths (approx. 78.5' face-to-face of barrier in both directions on I-75)||MOT scheme does not impact proposed final bridge widths (approx. 78.5' face-to-face of barrier in both directions on I-75)|
|Significant Impacts For Construction Duration (See Note 2)||Shortest construction duration on I-75. Bridges are constructed in two sequential steps, in the second construction season.||Moderate. Construction of I-75 median area would occur in the first construction season (with minimal impact to existing traffic. I-75). Most construction would be completed in the second construction season (similar to Option 1). However, an additional one to three months would likely be required (in a third construction season) to complete median construction along I-75.|
|Significant Impacts To Permanent Earthwork, Retaining Walls, Etc.||No impacts to these permanent design features are anticipated.||No impacts to these permanent design features are anticipated.|
|Ability To Maintain Existing Drainage And Lighting Systems||No special provisions required.||Temporary drainage features and ditch work will be required in Stage 3 to maintain drainage in areas adjacent to x-over access to the SR-63 interchange ramps.|
|Constructability And Construction Equipment Access||Adequate and safe work zones along I-75. Potentially difficult contractor access is common with part-width construction.||Improves contractor access and work space for construction of NB I-75. Facilitates efficient construction zones. Design of access to and from interchange ramps becomes more complicated, although is routine work for most contractors.|
|Ability To Meet TEM Policy||Would not meet minimum lane width requirements on the existing bridge decks. 33' face-to-face of barrier for three lanes would be provided (36' min. required per TEM), in second construction season.||Conforms with lane width and shoulder widths required in the TEM.|
|Location Of Crossovers (e.g., can cross-over be located near the project?)||The crossovers outside this project's limits will be constructed as part of BUT/WAR-75, designed by Balke.||The crossovers outside this project's limits will be constructed as part of BUT/WAR-75, designed by Balke. The crossovers to maintain access to SR 63 can be provided with DSD in conformance with the TEM (see Strip Map Exhibits A through G).|
|Other Misc. MOT Costs||Temporary pavement, embankment, and PCB on two sides of the freeway ($1.0M). Partial demolition required for three structures ($0.2M). (See Note 1.)||Temporary pavement, embankment, and PCB on one side of the freeway ($0.5M). Temporary ramp crossovers are required to maintain access to SR 63 in Stage 3 (0.2M).|
|Estimated MOT Cost (See Note 2.)||$2.2M||$1.7M|
ODOT MOT Alternatives Analysis
The ODOT MOTAA - How/Why
- ODOT is embarking on the largest construction program(s) in our history
- Director was concerned about the impact our work zones will have on crashes
- Director's Question - Are the ODOT work zones causing more accidents?
If so, can we do more to limit the increase?
The "Knee Jerk" Reaction
- "Well of course we have more crashes in work zones. Narrow lanes, barriers next to lanes, and on... and on... . and on... ."
- Turns out there were things we could do better!!
- Began analyzing work zone crashes
- Performed "Before/After" comparison of crash rates
- Results were startling:
Next Step -> More Analysis -> The Conclusions
The "abnormally" high concentrations of crashes showed there are major geometric contributing factors to work zone crashes:
- Inadequate off-ramp capacity (not covered by MOT policy)
- Inadequate ramp merges
- Insufficient paved shoulders
The Geometric Problems
- Ramp merges - Created new standards for work zone on ramp merges. Merges are now required to be detailed in plans. (Problems noted in MOTAA)
- Paved shoulders - Created "desired" cross section that requires a 2' paved shoulder (Problems noted in MOTAA)
- Off ramp capacity - Explicitly looked for in Maintenance of Traffic Alternative Analysis (MOTAA).
The ODOT MOTAA
- So what does all this have to do with the MOTAA?
- The MOTAA is also a process that ensures we won't replicate the geometric problems discovered through our crash analysis
- Past problems don't get replicated
- Potential WZ problems are identified early in the project development process when there is still time to take action
- Identifies "best" option for a WZ (part width, crossover, contra flow, hybrid)
- Problem "fixes" are scoped into the subsequent detail design steps of the process
- Identifies important innovative contracting opportunities
Work Zone Crashes
Work Zone Crashes - Reactive Measures
- ODOT is obtaining work zone crash reports in nearly real time from local law enforcement.
- Crashes are input into a database application that sorts crashes into one half-mile segments for comparison to historical pre-construction average crash frequency.
- Work zone crash reports are used to look for "abnormally" high concentrations of crashes.
- When found field visit ensues to find causes and fixes.
Misc. MOT Topics
Related MOT Topics
- Every Interstate and look-alike work zone is inspected and rated by Central Office for adherence to standards, specifications and for safety concerns
- Any safety concerns are immediately brought to the attention of the district for correction
- Results of these inspections are part of Organization Performance Index (OPI)
- Each District Deputy Director is held accountable for their OPI performance
- ODOT undertaking largest training initiative in our history
- One of the many required classes (for 2500 ODOT highway workers, project inspectors, etc) is work zones
- Testing and certification are part of the training classes
- Consultants now required to attend ODOT WZ Design training class as part of their prequalifications. Testing & certification required.
Misc. MOT Topics
- More open to complete closures; particularly for urban bridge overlays.
- Maximum deck area is currently 23,000 square feet
- Close Friday @ 8 pm
- Open for Monday rush hour
- Must be cautious of "blow throughs"
- Ground Penetrating Radar