Figure 1 -1: A graph comapring vehicle miles traveled versus lane milage between 1990 and 1998. The x-axis (horizonal axis) shows years with even years labeled starting with 1990 and ending with 1998. Unlabled tick marks are provided for uneven years. The y-axis (vertical axis) show values from 100 to 180 in divisions of 10. From 1990 to 1998 vehicle miles traveled increasaed iat a steady rate from 140 in the year 1990 to 170 in the year 1998. The rate of growth from 1990 to 1991 and from 1995 to 1996 was slightly less than all other years shown. From 1990 to 1998, lane mileage was overall mostly flat beginning in 1990 with a value of approximately 101 and ending in 1998 with a value of approximalty 102. From years 1990 to 1991 lane milage increased by appromilaly 1 mile. From years 1991 to 1996 lane milage held steady at a value of approximatley 102. From 1996 to 1997 lane milage increased to a value of approximately 103, but then fell back to a value of approximately 102 in the period from 1997 to 1998. Return to previous page.
Figure 1 -2: Graphic: Freeway Management Programs and their relationship with the Surface Transportation Program. The graphic illustrates the relationship using peices of a puzzle. In the background of the graphic are a series of connected puzzle pieces is shown with a block of puzzle pieces missing. The missing block of puzzle pieces is brought forward and appear larger in size. These puzzle pieces represent the six freeway management programs. The puzzle pieces are arranged in a block 3 puzzle pieces high and 2 puzzle pieces wide. Starting at top left, and continuing down, the puzzle peices are labeled; HOV Treatments, Ramp Management, and Incident Management. Similarly, the puzzle pieces on the right side of the block starting with the top puzzle piece and continuing down are labeled; Information Dissemination, Surveillance and Incident Detection, and Lane Use Control. All puzzle pieces are white with the exception of the puzzle piece labled "Ramp Management". This piece is colored to emphasize its relationship to the Freeway Management Program. In order for Ramp Management to be successfully achieved it must fit in with other Freeway Management and for that matter Surface Transportation Porgrams. Return to previous page.
Figure 1-3: Document Organization by Main Section. Graphic shows the organization and flow of the 11 chapters that comprise the Ramp Management Handbook. The chapters are grouped into 4 higher-level topic areas that make it easier and quicker for readers to get the information they need. These higher-level topics areas are shown as text boxes arranged with three boxes staked vertically and one box turned on its side. The text box turned onto its side is as wide as the other three boxes are as tall. The three text boxes stacked vertically are labeled (starting at top); Getting Started, Decision making, and Influences. The forth text box, postioned on its side, is labeled "Visibility". Within these four text boxes are the chapters each contain. The "Getting Started" text box represents the logical beginning of the handbook and contains the first four chapters (Chapters 1-4). The text box labeled "Decision Making", represents the next logical pregression in the handbook and contains the next four chapters (Chapter 5-8). The third text box is labled "Influences" and contains Chapters 10 and 11. Chapter 9 is contained in the fourth text box labeled "Visibility". Due to its inter-relatedness with other other sections, the "Visibility"section may be read at anytime and does not need to follow any particular section. Return to previous page.
Figure 3-1: This is a graphic of the Traffic Management Development Program Process. It shows a funnel with seven layers of increasingly darker gradations as you start from the top and proceed to the narrow tip. Each layer has text describing a different part of the traffic management development program process. The layers (from top to bottom) are "VISION, POLICIES, GOALS", "NEEDS AND POTENTIAL SERVICES", "CONCEPT OF OPERATIONS", "DETERMINE PERFORMANCE MEASURES", "DECISIONS (MANAGEMENT SYSTEMS, STAFFING, OTHER IMPLEMENTS)", "OPERATIONS STAFF TOOLS", AND "OPERATOR ACTIONS".
At the bottom tip of the funnel is an arrow that comes down and points to the left. It leads to text that says, "EFFECTS & OUTCOMES (EVOLUTION, REFINEMENT)". This text is then connected to another arrow that points upward and goes to the upper left-hand corner of the graphic pointing to text that says, "REGIONAL/STATEWIDE TRANSPORTATION PLANNING". On the right side of this text is another arrow that goes to the right and then points downward into the funnel.
In the upper right-hand corner of the graphic is the text, "INSTITUTIONAL ENVIRONMENT/STAKEHOLDERS". To the left of this text is an arrow that goes to the left and then points downward into the funnel. Return to previous page.
Figure 3-2: This is the Transportation Tier Diagram. There are four tiers that represent the various planning horizons. To the left of the four tiers is a vertical rectangular box that runs perpendicular to it. This rectangular box on the left-hand side is entitled, "LEGISLATIVE, REGULATORY & RESEARCH: NATIONAL, STATE & LOCAL ENABLING MECHANISMS." There are four double-headed arrows that extend horizontally from this box on the left-hand side to each of the four tiers on the right-hand side. Within this box is another rectangular box of a lighter shading that contains four bullets. The four bullets are: "AUTHORIZING LEGISLATION", "FEDERAL REGULATIONS", "FEDERAL POLICY", AND "RESEARCH PROGRAM."
The top tier of the diagram is entitled, "STRATEGIC LONG RANGE PLANNING & INVESTMENT DECISION MAKING (AT LEAST 20 YEARS)." Within this rectangular box is another rectangular box of lighter shading. On the left-hand side are three bullets. These bullets are "FREEWAY NETWORK PLANS", "CORRIDOR TRANSPORTATION PLANS", AND "HOV SYSTEM STRATEGY PLAN AND PROGRAM." On the right-hand side is a flow chart of four boxes that are arranged in a N/S/W/E pattern. Each of the boxes is connected to the other with a double-headed arrow, with the exception of the north and south boxes. The north box is "AGENCY & COMMUNITY STRATEGIC PLANS". The east box is "CORRIDOR HIGHWAY/FREEWAY IMPROVEMENT PLANS". The south box is "SYSTEM STRATEGIC PLANS (e.g. FREEWAY NETWORK, TRANSIT)". The west box is "REGIONAL TRANSPORTATION PLANS".
The second tier of the diagram is entitled, "PROGRAM AND SYSTEM PLANNING & INVESTMENT DECISION MAKING (3-20 YEARS)." Within this rectangular box is another rectangular box of lighter shading. On the left-hand side, there are two bullets which say, "REGIONAL PROGRAMS OR ORGANIZATIONS AND PLANS" AND "AGENCY PROGRAMS AND PLANS - STIP". On the right-hand side of the box is a flow chart of four boxes arranged in a N/S/W/E pattern. Each of the boxes is connected to the other with double-headed arrows, except the north and south boxes. The north box is "REGIONAL CONGESTION MANAGEMENT SYSTEM PLANS". The east box is "TRAFFIC MANAGEMENT SYSTEM STRATEGIC/PROGRAM PLANS". The south box is "REGIONAL AGENCY PROGRAM AND PLANS (e.g. TRAFFIC OPS., FREEWAY/MGMT.)". The west box is "REGIONAL/AGENCY IMPROVEMENT PRGMS. (e.g. STIP, TIP)".
The third tier of this diagram is entitled, "PLANNING, DEVELOPING & PREPARING FOR DAY-TO-DAY OPERATIONS (1-3 YEARS)." Within this rectangular box is another rectangular box of lighter shading. It contains a flowchart of four boxes arranged in the N/S/E/W pattern. Each of the boxes is connected to the other with a double-headed arrow, except for the west and east boxes. The north box is "TRANSPORTATION MANAGEMENT PLANS, OPERATIONAL STRATEGIES, AND TRAFFIC CONTROL PLANS." The east box is "TRAFFIC MANAGED SYSTEMS DESIGN & ENHANCEMENTS." The south box is "SUPPORT PROGRAMS & SERVICES (e.g. TRAVELER INFO., INCIDENT MGMT.)." The west box is "DEVELOPING ROADWAY IMPROVEMENT PROJECTS."
The fourth tier is entitled, "DAY-TO-DAY OPERATIONS (REAL-TIME TO 1 YEAR)." Within this rectangular box is another rectangular box of a lighter shading. It contains 7 bullets. They are: "TRAFFIC CONTROL DEVICE OPERATION AND MAINTENANCE", "PERFORMANCE MONITORING AND REPORTING", INCIDENTS (e.g. ADVERSE WEATHERS, CRASHES)", "WORK ZONE TRAFFIC MANAGEMENT", "MODIFYING TRAFFIC SIGNAL TIMING PLANS", "EMERGENCY SERVICE PATROL SERVICE", AND "ROADWAY MAINTENANCE." Return to previous page.
Figure 5-1: Graphical plot, against time (horizontal axis) of the following:
Flow (vehicles per hour per lane) -- left vertical axis
Speed -- right vertical axis
As discussed in the text, as volume increases, speed slightly decreases. When volume reaches capacity, it "breaksdown", resulting in a rapid and significant drop in both speed and flow rate. Return to previous page.
Figure 5-2: Graph showing the generalized relationship between volume (vertical axis) and density (horizontal axis). The curve and the associated relationships are described in the text. Return to previous page.
Figure 5-3: Shows two graphs -- the top is a graph of Fuzzy Classes (vertical axis) against local Occupancy (horizontal axis); the bottom is a graph of Fuzzy Classes against downstream occupancy. The details of the plots are decribed in the text. Return to previous page.
Figure 5-4: Shows the SWARM data flows as follows:
raw data - failure management - data normalization - station statistics - dynamic saturation analysis - systemwide adaptive ramp metering algorithm - metering rates. The figure also shows the following constraints feeding onto the ramp metering algorithm: minimum metering rates, time-of-day metering rates, HOV bypass, unrestricted entries, incident and special event response plans, missing and deficient data, queuing overides, and operator overrides. Return to previous page.
Comparision of ramp meter queue storage with and without a right-turn lane on an arterial street. The graphic contains two similar illustrations of a typical freeway entrance ramp/arterial intersection. The illustration on the left shows the ramp/arterial intersection without ramp terminal improvements and the illustration on the right shows the same intersection with a right turn lane added. Both illustrations have vehicles superimposed on the ramp and arterial to show how operations on the arterial would be affected with and without a right-turn lane. In the illustration without a right turn lane, the queue that forms at the ramp meter flows back into the adjacent arterial intersection and onto the right lane of the arterial. This prevents the smooth flow of through traffic on the arterial as the right lane is essentially blocked to through traffic. In the illustration with a right turn lane, queues that form at the ramp meter are contained to the right turn lane. This eliminates queueing impacts to through traffic on the arterial. Return to previous page.
Figure 6-1: Graphic:
Figure 6-1: High-level screening for ramp management strategies.
Step 1: Asses Agency/ Regional Policies, Goals, and Objectives. Elements to consider are strategic Plan, Business Plan, Regional Transportation Plan, Policy Documentation.
Proceed to Decision #1: Do plans and policies support ramp management strategies?
If YES then Proceed to Step #2: Evaluate Current/Baseline Conditions.
If NO then ramp management strategies are not needed or applicable.
Step #2: Evaluate Current/Baseline conditions. Elements to consider are congestion and delay, collisions and safety, roadway geometry, public opinion, and other impacts.
Proceed to Decision #2: Are freeway, ramp and adjacent arterial operations satisfactory?
If YES: Then ramp management strategis are not needed or applicable.
If NO: Then proceed to step #3: Assess needs that can be addressed by ramp management strategies.
Step #3: Assess needs that can be addressed by ramp manaement strategies. Elements to consider are safety, congestion, convenience, access, ramp capacity and queues, and adjacent facility operations.
Proceed to Decision #3: Can needs be addressed by ramp management?
If YES: Select specific ramp management strategies for further study (Table 6.1).
If NO: Ramp management strategis not needed of applicable.
Return to previous page.
Figure 6-2: Graphic:
Figure 6-2:Ramp Meter Selection Decision Tree (Part 1of 2)
Steps 1&2 to be completed simultaneously.
Step #1: Refine Problem Analysis. Elements include; type and severity of collisions, extent and severity of mainline congestion and neighborhood conditions.
Step #2: Assess severity of ramp metering impact. Elements include; diversion, equity, ramp emissions, arterial impacts, public perception, ramp geometry and spacing.
Proceed to decision #1: Is ramp metering feasible? Point A from Figure 6-3 is also an imput to this decision.
If YES: Proceed to Step #3: Define geographic extent.
If NO: Investigate other viable ramp management strategies.
Step #3: Define geographic extent. Elements include; define geographic exent of strategy (e.g., Freeway segment, cooridor, regionwide) and determine continuity of problem.
Proceed to decision #2: Are problems isolated?
If YES: Implement local ramp metering.
If NO: Implement Systemwide ramp metering.
Proceed to decision #3: Can detectors be installed?
If YES: Implement traffic responsive meters.
If NO: Implement pre-timed meters.
Proceed to Point B on Figure 6-3.
Figure 6-3: Graphic:
Figure 6-3: Ramp Meter Selection Decision Tree 2 of 2
Continued from poitn "B" on Figure 6-2.
Decision #4: Is communication to field feasible?
If YES: Implement centrally managed ramp metering system.
If NO: Cannot implement a central control/monitoring system.
Step #4: Select Algorithm. Elements include; queue management, demand variability, severiy of problem, review applicable algorithms.
Proceed to Step #5.
Step #5: Assess special use bypass.
Proceed to Step #6.
Step #6: Determine flow control. Elements include; demand of ramp, signle lane single release, single lane dual release, two lane metering.
Proceed to Step #7.
Step #7: Conduct detailed analysis. Elements include; use analysis tools and models, traffic operations analysis, safety (crash) analysis, benefit/cost analysis, cost effectiveness.
Proceed to Decision #5.
Decision #5: Is ramp metering plan acceptable.
If YES: Proceed to detailed design and implementation of metering system.
If NO: Modify high-level system definition and return to Point A on Figure 6-2.
Figure 6-4: Graphic:
Figure 6-4: Ramp closure decision tree.
Steps 1 and 2 to be completed simultaneously.
Step #1: Refine Problem Analysis. Elements include; severity, time of day issues, events, vehicle class, origin and destination.
Step #2: Assess severity of ramp closure impact: Elements include; safety, neighborhood (Social and economic), congestion, accessibility, environmental.
Proceed to Decision #1: do ramp closure benefits offset severity of existing problem.
If YES: Proceed to Decision #2.
If NO: Investigate other viable ramp management strategies.
Decision #2: Select extent of ramp closure.
If Event Related (e.g., workzone/ construction, special events, emergencies and incidents) Proceed to Step 4A: Detailed Analysis of Temporary Ramp Closure.
If Time-of-Day related (e.g., peak period closure, off-peak period closures) proceed to Step 4B: detailed analysis of time-of-day closure.
If Permanent (e.g., severe safety problems) proceed to step 4C: Detailed analysis of permanent ramp closure.
Detailed analysis of each type of closure includes the following elements; cost effectiveness, benefit/cost analysis, final impacts, and political impacts.
Proceed to Decision #3: Do ramp closure benefits offset severity of existing problem?
If YES: Implement ramp closure if other viable solutions do not exist.
If NO: Investigate other viable ramp management strategies.
Return to previous page.
Figure 6-5: Graphic:
Figure 6-5: Decision Tree for Special Use Treatments that Target Safety Impacts at Merge Points.
Steps 1 and 2 to be conducted simultaneuously.
Step 1: Refine problem analysis. Elements include; geometric deficiencies, time of day impacts, traffic volumes and speeds, type and severity of collisions.
Step 2: Assess Severity of Special Use Impact. Elements include; truck re-routing, queuing, neighborhood impacts, and analyze impact of truck restriction.
Proceed to Decision Box #1: Does poor geometrics contribute to the problem.
If YES: Proceed to Decision Box #2.
IF NO: Investigate other ramp management strategies.
Decision Box #2: Is problem largely isolated to certain times of the day?
If YES: Detailed analysis of truck restrictions by time of day. Elements include; cost effectiveness, benefit/cost, final impacts, political impacts.
If NO: Detailed analysis of permanent truck restrictions. Elements include; cost effectiveness, benefit/cost, final impacts, political impacts.
Figure 6-6: Graphic:
Figure 6-6: Decision Tree for Special Use Treatments that Target Neighborhood Impacts.
Steps 1 and 2 to be completed simultaneously.
Step #1: Refine problem analysis. Elements include; geometric deficiencies, existing traiffc composition, determine truck volumes, and determine target traffic levels and speeds.
Step #2: Assess severity of special use impact. Elements include; traffic levels and speeds, neighborhood impacts.
Proceed to Decision #1: Are traffic levels and speeds achieved by restricting trucks?
If YES: Detailed analysis of truck restrictions. Elements include; cost effectiveness, benefit/cost, final impacts, political impacts.
If NO: Proceed to Decision #2.
Decision #2: Does poor geometrics contribute to the problem?
If YES: Detailed analysis of truck restrictions with other implemented strategies. Elements inlcude; cost effectiveness, benefit/cost, final impacts, political impacts.
If NO: Investigate other viable ramp management strategies.
Return to previous page.
Figure 6-7: Graphic:
Figure 6-7: Decision Tree for Special Use Treatments that Target Construction Impacts.
Steps #1 and #2 to be completed simultaneously.
Step #1: Refine Problem Analysis. Elements include; ramp traffic analysis, geometric deficiencies, determine target traffic levels and speeds.
Step #2: Assess Severity of Special Use Impact. Elements include; Traffic levels and speeds, construction.
Proceed to Decision #1: Does Severity of Problem Indicate Need for Ramp Closure?
If YES: Detailed Analysis of Ramp Closure. Elements include; cost effectiveness, benefit/cost, final impacts, political impact.
If NO: Proceed to Decision #2.
Decision #2: Are Ramp Management Strategies Inlcuded in the Work Zone Traffic Control Plan?
If YES: Detailed Analysis of Ramp Management Strategies Indentified in Work Zone Traffic Control Plan. Elements include; cost effectiveness, benefit/cost, final impacts, political impact. This step also feeds into Decision #3.
If NO: Proceed to Decision #3.
Decision #3: Does Ramp Demand Need to be Reduced (or further reduced)?
If YES: Detailed Analysis of Vehicle Class Restrictions and Priority Treatments. Elements include; cost effectiveness, benefit/cost, final impacts, political impact.
If NO: Investigate Other Viable Ramp Management Strategies.
Figure 6-8: Graphic:
Figure 6-8: Decision Tree for Special Use Treatments that Target Special Event Related Impacts.
Steps #1 and #2 to be completed simultaneously.
Step #1: Refine Problem Analysis. Elements include; local traffic conditions, special event congestion, special event collision history, queue and delay impacts, alternate routes, need for emergency access.
Step #2: Assess Severity of Special Impact. Elements include; traffic levels and speeds and neighborhoods.
Proceed to Decision #1
Decision #1: Does Severity of Problem Indicate Need for Ramp Closure.
If YES: Detailed Analysis of Full Closure. Consider emergency access needs.
If NO: Proceed to Decision #2.
Decision #2: Are Special Use Policies/Incentives in Special Event Management Plan?
If YES: Detailed Analysis of Special Use Treatments. Elements inlcude; HOV, transit and delivery vehicle impact, participants, cost effectiveness, benefit/cost, political impact.
If NO: Investigate Other Viable Ramp Management Strategies.
Figure 6-9: Graphic:
Figure 6-9: Decision Tree for Special Use Treatments that Target Policies.
Decision #1: Does Policy Support Special Use?
If YES: Proceed to Step #1 - Refine Problem Analysis.
If NO: Investigate Other Viable Ramp Management Strategies.
Step #1: Refine Problem Analysis. Elements inlcude; special class demand, downstream attractors/upstream generators, estimate volume. Proceed to Decision #2.
Decision #2: Does Demand of Special Class Warrent Special Use Ramp?
If YES: Detailed Analysis of Special Use. Elements include; cost effectiveness, benefit/cost, final impacts, and political impact.
If NO: Investigate Other Viable Ramp Management Strategies.
Figure 6-10: Graphic:
Figure 6-10: Ramp terminal treatment decision tree.
Step #1: Refine Problem Analysis. Elements include; ramp and arterial traffic analysis, special event congestion and traffic flow, historical collision analysis, geometric deficiencies, determine if there are target traffic levels and speeds, upstream and downstream traffic generators.
Proceed to specific treatment matrix.
The specific treatment matrix. Left column is labeled "Impacts", middle column is labeled "Location to Implement Strategy", and the right column is contains all the various ramp terminal treatments (from left to right these are; widening, channelization, signal timing, turn restrictions, geometrics, warnings, lane assignment). Ramp terminal strategies that are available based on impacts and location are as follows:
Congestion on-ramp = Widening, channelization, and signal timing
Congestion off-ramp = Widening, channelization, and signal timing
Congestion arterial = Widening, channelization, signal timing, and turn restrictions
Safety on-ramp = Widening, channelization, signal timing, geometrics, and warning
Safety off-ramp = Widening, channelization, signal timing, geometrics, warning, and lane assignment
Safety arterial = Widening, channelization, signal timing, geometrics, warning, and lane assignment
Downstream impacts = Channelization, signal timing, turn restrictions, warning, and lane assignment
Downstream impacts = Channelization, signal timing, warning, and lane assignment
General Activities Timeline for Ramp Ranagement Strategy Implementation.
Activities to be completed before ramp meter startup/turn on are listed in the order in which they should be initiated below:
Project Phasing (Section 7.2)
Intra-Agency Readiness (Section 7.3)
Agency Agreements Policies and Procedures (Section 7.4)
Public Information and Outreach (Section 7.5)
Testing and Start-up (Section 7.6)
Activity to be completed after ramp meter startup/ turn on is listed below:
Monitoring and Managing Initial Operation ( Section 7.7)
Diagram: Systems Engineering Process (Vee Diagram)
Step 1: Concept of Operations (Beginning or Process)
Step 2: High-level Requirements
Step 3: Detailed Requirements
Step 4: High Level Design
Step 5: Detailed Design
Step 6: Implementation (Mid Point)
Step 7: Integration and Test
Step 8: Subsystem Verification
Step 9: System Acceptance
Step 10: Operations and Maintenance (End of Process)
This figure shows the modeling versus measurement curve. The vertical axis is the "COST OF DATA COLLECTION" ranging from low to high. The horizontal axis is "TRAFFIC CONDITIONS" ranging from predictable to unpredictable. The curve is a slight "S" curve starting about 1/3 up the cost scale and then progressing in a gradual "S" curve to the upper 4/5 of the cost scale. The top half of the curve is white and is labeled "MODEL". The bottom half of the curve is blue and is labeled "MEASUREMENT".
Graphic:
This figure shows an example of the ramp metering impacts on corridor volumes. In the upper left hand corner is the legend. The hollow green circles show where there is an increase in volume. The largest green circle represents an increase in 1,500 or more vehicles, the middle green circle represents an increase in 500 to 1,500 vehicles, and the smaller green circle represents 0 to 500 vehicles. The solid red circles show where there is a decrease in volume. The smallest red circle represents a decrease in 0 to 500 vehicles, the middle red circle represents a decrease of 500 to 1,500 vehicles, and the largest red circle represents a decrease of 1,500 or more vehicles.
The lowest left hand corner has another legend showing the average traffic volumes with and without ramp metering. The three corridors are "I-35E", "RICE", and "EDGERTON". The volumes with ramp metering are 14,552, 1,652 and 1,395, respectively. The volumes without ramp metering are 12,140, 1,538, and 1,742, respectively.
On the right-hand side of the figure, the I-35E corridor shows one small red circle at the south end and then eight large red circles spread along the corridor to just north of 36. The Rice Street corridor is west of I-35E and has four small red circles spread evenly along the corridor and two small green circles near 36. The Edgerton Street corridor has four small green circles and one small red circle, mostly located at the north end of the corridor.
This figure shows speed variability impact along with control variables. At the bottom of the graph is the legend showing condition (meters off or meters on), date (Monday, October 16, 2000 and Monday, October 9, 2000), field (25' for both conditions), sample (100% for both conditions), and volume (25,181 for meters off and 25,294 for meters on).
The detector is "3136-94/25AvE3". The vertical axis is "SPEED (miles per hour)" ranging from 0 to 100. The horizontal axis is "TIME (hour of day)" ranging from 3:15 to 6:15 PM.
The meters on condition shows a green line hovering around 60 mph. The meters off condition shows a red line starting at about 50 mph, increasing to about 65 mph and then fluctuating up and down in the 20 to 40 mph range until 6 PM, at which time it jumps up to 60 mph by 6:15 PM.
This figure is a screenshot of a Paramics model showing a sample 3D graphic. The background is a topographic grayscale basemap. It shows traffic at a freeway interchange (vehicles are yellow or white, small trucks are blue, and large trucks are purple). The on- and off-ramps show the queues that are forming due to congestion. Yellow concentric circles are shown where the congestion is the most severe. Return to previous page.
Table 9-7: Mapping of Analysis Needs to Common Traffic Analysis Tools
|
|
Traffic Analysis Tool Category |
|||||||
Study Area |
Problem Area |
Direct Measurement |
Sketch-Planning Tools |
Travel Demand Models |
Analytical/Deterministic (HCM-Based) |
Macroscopic Simulation |
Mesoscopic Simulation |
Microscopic Simulation |
Signal Optimization Tools |
Localized |
Merge/Weave |
ü |
ü |
|
ü |
ü |
ü |
ü |
|
|
Ramp Operations |
ü |
ü |
|
ü |
ü |
ü |
ü |
|
|
Freeway Operations |
ü |
ü |
|
ü |
ü |
ü |
ü |
|
|
Arterial Operations |
ü |
ü |
|
ü |
ü |
ü |
ü |
ü |
Corridor |
Merge/Weave |
ü |
ü |
|
ü |
ü |
ü |
ü |
|
|
Ramp Operations |
ü |
ü |
|
ü |
ü |
ü |
ü |
|
|
Freeway Operations |
ü |
ü |
ü |
ü |
ü |
ü |
ü |
|
|
Arterial Operations |
ü |
ü |
ü |
ü |
ü |
ü |
ü |
ü |
Regional |
Merge/Weave |
Not typically performed for a regional study |
|||||||
|
Ramp Operations |
ü |
ü |
ü |
|
|
|
|
|
|
Freeway Operations |
ü |
ü |
ü |
|
ü |
|
|
|
|
Arterial Operations |
ü |
ü |
ü |
|
ü |
|
|
|
This is a flowchart describing the NEPA process overview. The cyan box in the upper left hand corner asks the question, "Is the proposed activity a FHWA action?" If no, then it leads to an orange box to the right which says, "NEPA does not apply". If yes, then then it leads to a box below it that says, "Does the action require federal approval? (23 CFR771.109(a)(1))".
If no, then it leads to an orange box to the right that says, "See NEPA CE Determination Decision Tree for additional considerations and decisions." If yes, then it leads to a cyan box below that says, "Does the action meet the Categorical Exclusion criteria? (23 CFR771.117(a))".
If yes, then it leads to the same orange box described earlier that says, "See NEPA CE Determination Decision Tree for additional considerations and decisions."
If no, then it leads to a cyan box below which says, "Is the project a "Class I" Action? (A list of actions that significantly affect the environment)(23 CFR771.115)". If no, then it leads to an orange box to the right which says, "Project reqiures a NEPA Environmental Assessment to determine whether there are significant environmental impacts." It then leads to a cyan box below it which says, "Does the Environmental Assessment indicate there would be significant environmental impacts?" If no, then it leads to an orange box below it that says, "Prepare Finding of No Significant Impact (FONSI)." If yes, then it leads to an orange box to the left which says, "Project requires preparation of Environmental Impact Statement (EIS). See EIS Process Flowchart."
When answering the earlier question, "Is the project a "Class I" Action? If yes, then it leads to the same orange box mentioned earlier which says, "Project requires preparation of Environmental Impact Statement (EIS). See EIS Process Flowchart."
From this point, there are more orange boxes below that lead to "Notice of Intent", followed by "Scoping, Consultation and Coordination", "Prepare Draft EIS. See Review and Approval Process for DEIS", "Circulate DEIS to public" and "Prepare Final EIS. See Review and Approval Process for FEIS." This then leads to an orange box to the right which says, "Project approved by FHWA via Record of Decision (ROD)".
There is also a note at the end of the chart which says, "U.S. Coast Guard or other federal lead agencies for NEPA compliance have separate regulations."
Return to previous page.
This figure shows the ramp meter elements. There is a freeway (3 lanes) with an on-ramp from a frontage road or surface street. Just prior to a motorist entering the on-ramp, an advance ramp control warning sign with flashing beacon is located on the left-hand side of the frontage road. On the on-ramp, there is a queue detector, followed by a check-in detector (where multiple detectors may be used) up until the motorist reaches the stopline. At the stop line, there are ramp meter signals on both sides of the on-ramp. After crossing the stop line, there is a check-out detector. The controller is located off to the right-hand side of the on-ramp. As the motorist merges with mainline traffic, there is an optional merge detector. On the mainline, there are mainline detectors located in the center of each of the three freeway lanes. Return to previous page.
This figure is an example HOV bypass lane. It shows an HOV bypass lane with diamond symbols in the center of the lane. This lane is on the left hand side of the on-ramp. The general purpose (GP) lane is on the right-hand side and has a stop bar with a ramp meter located on the right side of the roadway (50' from the stopbar). Just beyond the stop bar after the HOV and GP lanes merge is an observation point/enforcement area (14' width and 200' length) located off to the right-hand side. The single lane (after HOV and GP merge) has a width of 15'.
Notes at the bottom of the figure state the following:
(1) See Standard Plans for striping details.
(2) See Chapter 940 for on-connection details and for acceleration lane length.
(3) See Chapters 940 & 641 for ramp lane and shoulder widths for a 2-lane ramp.
(4) A transition curve with minimum radius of 3,000 feet is desirable. The minimum length is 300 feet. When the mainline is on a curve to the left, the transition may vary from a 3,000 feet radius to tangent to the mainline.
This figure shows an example of freeway-to-freeway metering. The two lanes of traffic are coming from one freeway and preparing to merge with traffic on the next freeway. A third lane to the left of the two lanes is an HOV bypass lane which is also metered. Return to previous page.
This figure shows a type 2070V controller. It is a front and exposed top view of the controller showing the open slots for various cards and the power supply module. Return to previous page.
This figure shows a typical signal standard (not to scale). It is a type I standard pole. The upper signal head has three sections (300 mm sections) with a red status light for enforcement on the back. Below the upper signal head is a lower signal head which can either be two or three sections (200 mm sections). The centerline of the lowest section in the signal head should be at least 1350 mm above the roadway and parallel to it. An R89 or R90 (optional) cap at the bottom of the pole is located beneath the lower signal head. Return to previous page.
This figure shows signals mounted on a mast arms (for simultaneous release only). The bottom of the signal heads must be 5.2 (min) to 5.8 (max) meters above the roadway. There are three signal heads mounted to the mast arm (which are 1 meter from the R89-1 box with a note to "see standard plans for spacing" between the signal heads). The pole is a type 26 or 27 series standard. There is also another notes which says, "standard heads may be used on high speed approaches where sight distance is limited." Return to previous page.
This figure shows the typical passage and demand detector layout for a one-lane ramp. The type A detector loops are centered in the lane. The first passage loop is located 2.1 meters to the 300 mm limit line. A demand loop is then located 1.8 meters from the limit line. Another demand detector is located 3 meters from the first demand detector, followed by another one again 3 meters away. The lane is 3.6 meters in width, flanked by shoulders on both sides. Each loop is 1.8 meters by 1.8 meters. The limit line is at least 23 meters to the edge of gore. Return to previous page.
This figure shows the typical passage and demand detector layout for a two-lane ramp. The type A detector loops are centered in each lane. Each lane is 3.6 meters in width. Starting on the left side are the passage loops which are located 2.1 meters from the 300 mm limit line. Demands loops are 1.8 meters from the limit line and spaced 3 meters apart from each other. Each loop is 1.8 meters by 1.8 meters. There is an HOV diamond symbol in the left lane. The limit line is located at least 23 meters to the edge of gore.
This figure shows the typical passage and demand detector loop layout for a 3-lane configuration with a non-metered HOV lane. Starting from the left hand side, there are type A detector passage loops centered in each lane and are located 2.1 meters from the limit line. The demand loops are located 1.8 meters prior to the limit line (which only extends across the two general purpose lanes and not the HOV lane). Demand loops are spaced 3 meters apart. Each loop is 1.8 meters by 1.8 meters. Each lane has a width of 3.6 meters. The HOV lane is located on the left-hand side. The limit line is located at least 23 meters to the edge of gore. Return to previous page.
This figure shows a typical mainline detector loop layout. The type A detector loops are centered in each travel lane. Each loop is 1.8 meters (width) by 1.8 meters (length). Each of the two travel lanes has a width of 3.6 meters with a shoulder on the right-hand side. Loops are spaced 6.1 meters apart. Return to previous page.
This figure shows a typical queue/exit/count loop. The type A detector loop is centered in the lane. Each loop is 1.8 meters by 1.8 meters. The lane width is 3.6 meters with shoulders on both sides. Return to previous page.
This figure shows two different extinguishable message signs. The one on the top says "METER ON" with 300 mm yellow flashing beacons with blackplate on either side. The one on the bottom says "PREPARE TO STOP" with 300 mm yellow flashing beacons with blackplate on either side. Return to previous page.
This figure shows a typical advance warning signing layout for a freeway-to-freeway interchange. The freeway section starts at the lower right corner and curves left to the upper left corner. A point where the off-ramp is 7 meters from the mainline is noted - 30 meters from this point on the off-ramp is where the "METER ON" sign is located. Then 120-180 meters from that point, the "PREPARE TO STOP" sign is located.
The following notes are shown at the bottom:
(1) The "Prepare to Stop" message should be 120 m to 180 m downstream of "Meter on" message.
(2) If the queue extends upstream of the "Prepare to Stop" sign, the location should be adjusted to locate it upstream of the end of the queue.
(3) Signs may be mounted on the ground or overhead. If ground mounted, one sign on each side of the connector should be installed.
This figure is the HOV symbol. It is 3.6 meters tall and 975 mm wide. The width of the black line that makes up the HOV symbol is 150 mm. Return to previous page.
Figure 10-16: Sample HOV Sign7 Return to previous page.
Figure 10-17: Metered HOV Lane Sign Return to previous page.
This figure shows the Lunalilo ramp closure experiment layout (Lunalilo on-ramp and Vineyard Boulevard off-ramp). The top figure shows the "normal condition". There are three mainline lanes with a one-lane on-ramp that continues into an auxiliary lane which then becomes the left lane of the two-lane off-ramp. There is striping on the mainline between the center and right lanes which prohibits traffic from switching to the right, but permits it to the left.
The bottom figure shows the "experiment condition". It is the same configuration described above, except that there are cones set up on the left side of the on-ramp and continue on the left side of the auxiliary lane and the left side of the right lane of the two-lane off-ramp. This coning directs all on-ramp traffic to the right lane of the off-ramp. Return to previous page.
This figure shows a partial exit ramp closure. There are two lanes on the mainline and a one-lane off-ramp. There are cones that cordon off part of the off-ramp, but still leave a minimum of 3 meters in width. Signing consists of orange diamond signs with black text that says, "ROAD WORK XXX M" with a rectangular orange sign with black text that says, "ON RAMP". This sign is located at the beginning of the taper for the off-ramp. This sign is followed by another sign downstream that is a orange diamond with black text that says, "RAMP NARROWS" with a smaller orange rectangular sign below it that says "XX km/h". After the coning ends (150 m.), an orange rectangular sign with black text that says, "END ROAD WORK" is posted. Return to previous page.
Figure 10-20: Type III Barricade (Stored Position) Return to previous page.
Figure 10-21: Type III Barricade (Deployed) Return to previous page.
This figure shows a sample gate closure detail. It has a 29' pole with a luminaire on top (30' mounting height). Connected to the pole is a drop gate arm. When in the closed position, the arm shows a diagonally striped (slants to the left) bar with a sign attached just under the bar that says "ROAD CLOSED". Three red LED warning lights are mounted on top of the horizontal bar at various distances from the end. The drop gate arm guides are mounted at 10' and 26' from the bottom of the pole base plate. When the gate arm is dropped, its height is 3'-7" (min) to 4'-7" (max) from the roadway. Return to previous page.
This figure shows a vertical swing arm traffic gate in the closed position. The single horizontal bar has red and white diagonal striping that slants downward and to the right. On top of the bar is a warning light. The swing arm gate is mounted to a black pole near the base. Return to previous page.
Figure 10-24:Right Turn on Red Restriction Sign Return to previous page.
Figure 10-25: Left-Turn Restriction Sign Return to previous page.
This figure shows the Lunalilo Street on-ramp and the Vineyard Boulevard off-ramp lane configurations. The configuration on the top is the "normal" condition where there are three mainline lanes, a one-lane on-ramp on the left and a two-lane off-ramp on the right. The on-ramp lane becomes an auxiliary lane which connects to the left side lane of the off-ramp. There is solid lane striping on the mainline between right lane and the center lane -- this prohibits lane switching to the right, but permits it to the left.
The configuration at the bottom is the "experiment" condition with the same lane configurations as the above diagram, however there are now cones which prevent a motorist from getting onto the mainline from the on-ramp and directs him to the right lane of the off-ramp. Return to previous page.
This graph shows the evoluation of speeds across three freeway lanes from 7:45 to 8:00 AM. The vertical axis is speed measured in kilometers per hour. The horizontal axis is days of the week as well as the "normal" versus "experiment" conditions. There are four different lines on this graph, each representing a different lane (left, middle, right or auxiliary). The left lane is denoted with diamond symbols, the middle with squares, the right with triangles, and the auxiliary with the "x" symbol.
The left lane begins just above 50 km/hr for the three days (Tuesday through Thursday) in the normal condition. It then dips down to about 45 km/hr on the first day of the experiment and increases to about 48 km/hr by Thursday of that same week. During the second week of the experiment, the speed dropped to 40 km/hr and then increased to just over 50 km/hr by Thursday.
The middle lane begins at about 43 km/hr and increases to 48 km/hr by Thursday in the normal condition. It then dips down to 38 km/hr on Tuesday of the first week of the experiment. It steadily hovers around 44 km/hr until Thursday of the second week of the experiment.
The right lane begins at about 34 km/hr and increases to 39 km/hr on Thursday in the normal condition. It then dips down to 27 km/hr on Tuesday for the experiment condition and jogs up and down in the 30-40 km/hr range and ends at 40 km/hr on Thursday of the second week.
The auxiliary lane begins at 39 km/hr and ends at 40 km/hr for the normal condition. It then drops to 19 km/hr on the first day of the experiment. It then jogs up and down in the 28 to 38 km/hr range for the experiment and ends at about 36 km/hr. Return to previous page.