Traffic Analysis Tools Volume IX: Work Zone Modeling and Simulation
A Guide for Analysts
Maryland State Highway Administration Lane Closure Analysis Program
Maryland State Highway Administration
Lane Closure Analysis Program[8]
| Work Zone Characteristics | |
|---|---|
| Transportation Analysis: | |
| Approach | Sketch-Planning |
| Modeling Tools | Lane closure analysis program built within Microsoft Excel |
| Work Zones: | |
| Type | Type II – IV |
| Network Configuration | Isolated |
| Geographic Scale: | |
| Work Zone Size | Small |
| Analysis Area | Local |
Overview
The Maryland State Highway Administration (SHA) has developed the Lane Closure Analysis Program (LCAP) to support state traffic engineers with a structured method to analyze work zone impacts. The LCAP tool was developed based upon the guidance written in the Work Zone Lane Closure Analysis Guidelines which present allowable thresholds for decreasing mobility measured in terms of queues and delays in work zones. LCAP is part of a tiered approach to work zone analysis that SHA has developed. Depending on the complexity of a project, SHA recommends starting with LCAP for simple cases, QuickZone for simple cases with network impacts, and then simulation tools such as CORSIM, VISSIM, and SimTraffic for relatively complex scenarios requiring detailed analysis.
LCAP Description
LCAP is an analytical tool designed to quantify queues and delays resulting from capacity decreases in freeway work zones. LCAP is written as a program within Microsoft Excel and compares expected travel demand against work zone capacity on an hour-by-hour basis to estimate delay and mainline queue growth.
LCAP consists of a four-step process:
STEP 1
Open existing file or Start new file. The user has the choice of opening an existing LCAP file or starting a new case for analysis.
Enter project information. The Project Information screen allows the user to input data that defines the project. The project description, analyst’s name and date of analysis should be input here. The project description should contain information to identify the project, such as roadway name, direction of travel, segment of road, and work being performed.
STEP 2
Input demand. The demand is an essential part of the LCAP program. Users may enter their own data or access SHA’s traffic data from the Traffic Monitoring website (http://www.marylandroads.com/tmsreports/).
STEP 3
Describe the work zone. The closure analysis screen is used to determine the hours during the day when lanes can be closed without causing excessive queuing or delays. The user is prompted to select input options in terms of maximum allowable queue length or maximum allowable delay (to be highlighted in red or yellow when exceeded) and proposed lane closure hours. Using trial and error in the start and finish times of the work zone, lane closure schedules can be determined based on allowable queues or delays.
- Lane Closure Information—The user enters the total number of freeway lanes and the number of open lanes with the lane closure in effect.
- Capacity Information—The user enters the roadway capacity without and with the work zone in vehicles per hour per lane. The work zone capacity can be determined in four ways:
- engineering judgment,
- 1997 Highway Capacity Manual,
- University of Maryland Capacity Estimation equation, or
- 2000 Highway Capacity Manual equation.
- Output Type—The user selects queue length or delay as the measure of the work zones mobility impact. The user has the option of highlighting the output in red or yellow if the queue exceeds a specified length (miles) or the delay exceeds a specified period of time (minutes).
STEP 4
Save File. LCAP has the ability to save all of the data associated with the project.
[8] This case study was adapted from the LCAP User Guide available at http://marylandroads.com/safety/workzone.asp.
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