HCS2000^TM

HCS2000 Did You Know?

General

In all HCS2000 modules, there are links within the Help menus to automatically check for HCS2000 updates, connect you to the HCM2000 WebBoard for information on the Manual and to view current Highway Capacity Analysis training opportunities.

In all HCS2000 modules, input fields for "calculated" values (e.g. passenger car equivalents, or PCE's) can be overwritten by the user when appropriate. In these cases an asterisk appears in the report next to the overwritten value. All overwritten values can be automatically "restored" to their original calculated value by using the menu item Edit > Restore. A single value can be restored to its original calculated value by clearing and leaving the field.

To facilitate populating all data fields when importing partial data sets from other sources, fields blanked by the user will be replaced with default or calculated values when retrieving XML (.xml) data files, where the traditional (.hc?) files retain the blank fields.

Special (like accented) characters in the agency information and/or informational fields (like analyst, intersection or freeway, project description) can create problems in the XML code, which is used in generating the Formatted Reports and transferring data for the Estimation/Optimization in Signals.

Signals

The Estimation/Optimization button currently can both optimize pretimed signals for minimum delay (using SOAP2K) and estimate actuated phase lengths (frp, HCM2000 Chapter 16, Appendix B).

Alt-PrntScrn while the Quick Entry is active will place the graphic on the clipboard for pasting into a report as a intersection diagram with lane configurations and turning movement volumes.

On external links with no nearby upstream signal, arrival type must be specified as 3, and the upstream filtering/metering factor (I-factor) must be specified as 1.0, in order to reflect random vehicle arrivals.

If there is an adjacent signal less than one mile away, then the I-factor is likely less than 1.0, determined by the v/c ratio of the combined movements from that signal for each approach in HCM2000 Exhibit 15-7.

Typically, an analysis period (duration) is the peak 15 minutes of the peak hour. In this case, the duration is set to 0.25 (15 minutes) and the standard peak-hour factor is used to adjust the hourly volumes to the peak 15-minute flow rate. If the duration is set to 1.0 (60 minutes), then the peak-hour factor is also set to 1.0 to reflect no peaking adjustment since the entire hour is being analyzed.

Modifying the clearance (yellow plus all-red) times will now change the lost time, and therefore the resulting g/C Ratio and Capacity values, which directly affects delay and possibly LOS.

A screen resolution of at least 800x600 is required for the phasing graphics to display properly.

In the formatted Input Worksheet report, the arrows on intersection graphic represent lane groups, not individual lanes.

It is possible for vehicle delays to be relatively high on a movement with very little traffic volume. If the cycle length is long, and the green time is short, then any arriving vehicle will be delayed by having to wait through the long cycle length, regardless of traffic volume.

TwoLane

Version 4.1a contains a new TwoLane module implementing the procedures from Highway Capacity Manual (HCM2000) Chapter 20 for Two-Lane Highways. These computational procedures had remained unchanged throughout the 1985, 1994, and 1997 editions of the HCM. However, the procedures have now changed significantly as prescribed in the HCM2000, including increasing the base capacity from 2,800 to 3,200 pcph in both directions and adding a new directional analysis with the capability to analyze passing lanes.

Many computational procedures from the Highway Capacity Manual involve a "primary measure of effectiveness" that is used to determine an overall level of service for the facility in question. The procedures from HCM2000 Chapter 20 on Two-Lane Highways are unique in that there are effectively two primary measures of effectiveness used to obtain level of service for "Class I" highways. These measures are "percent time-spent-following" and "average travel speed". In order to achieve a specific level of service, Class I highways must meet both criteria by having a sufficiently low percent time-spent-following in conjunction with a sufficiently high average travel speed. "Efficient mobility" is considered paramount on "Class I" two-lane highways, where motorists expect to travel at relatively high speeds. Motorists do not necessarily expect to travel at high speeds on Class II highways. These highways may function as access routes to Class I facilities, serve as scenic or recreational routes, or pass through rugged terrain. On these highways, mobility is less critical, and level of service is defined only in terms of percent time-spent-following, without consideration of average travel speed.

Unsignal

The current TWSC procedure does not handle intersections along six-lane (three thru lanes on the major street) roads.

There have been HCM2000 updates to the flared right turn and upstream signal procedures in TWSC to better analyze these situations, which have been implemented in HCS2000.

Roundabout reports upper-bound and lower-bound capacity, but not level of service. It is recommended that projections be based on the lower-bound solution, and that the upper-bound solution becomes feasible as drivers become more experienced with roundabouts.

Weaving