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HERS-ST Highway Economic Requirements System - State Version: Technical Report

Chapter 8 Model Output

The HERS model produces an extensive variety of statistics describing the forecast state of the highway system, the costs and benefits of the implemented improvements, and the history of each section. This chapter describes the three forms of output produced by HERS: the printable text file, the comma-delimited system statistics files, and the comma-delimited section output files.

The HERS-ST GUI provides an array of tools for the manipulation of this output data and the creation of reports, charts, and maps. See the HERS-ST User's Guide for further information.

8.1 Printed Output

HERS outputs a text file, suitable for printing, that summarizes the overall system conditions and improvements selected by the model. Certain of the pages are optional and can be suppressed through settings in the RUNSPEC.DAT file. If all pages are requested, HERS will output 169 pages. The printable output consists of the following:

  1. One page of output summarizing the state of the system at the start of the run;
  2. For each funding period, one page of output summarizing the state of the system at the end of the funding period;
  3. For each funding period and for the overall analysis period, one page of output summarizing how the system is forecast to change between the beginning and the end of the period; and
  4. For each funding period and for the overall analysis period, many pages of additional output providing information on the costs and benefits associated with the selected improvements.

The output pages are presented in four layout formats, as discussed below. HERS places the printable output in a single text file named by the user in the specification file (RUNSPEC.DAT). Two of these formats are also available in comma-delimited layout.

8.1.1 The System Conditions Output Format

HERS uses this format for items one through three in the above list of output pages. In addition to the run number and run description information from the RUNSPEC file, this page contains the following information for each of the nine functional systems in the HERS database, with individually produced summary forecasts for the rural system, the urban system, and for the complete system:

  1. Miles in the system;
  2. Average PSR (paved sections only);
  3. Average IRI (inches per mile, paved sections only);
  4. Average speed;
  5. Congestion Delay (hours per 1000 vehicle-miles);
  6. Total Delay (hours per 1000 vehicle-miles);
  7. Total VMT;
  8. Travel-time costs (dollars per thousand vehicle-miles);
  9. Operating costs, listed for all vehicles combined and separately for four-tire vehicles and for trucks (dollars per thousand vehicle-miles);
  10. Crash costs (dollars per thousand vehicle-miles);
  11. Total user costs, which is a summation of travel-time costs, operating costs for all vehicles, and crash costs (dollars per thousand vehicle-miles);
  12. Number of crashes (per 100 million vehicle miles);
  13. Number of injuries (per 100 million vehicle miles);
  14. Number of fatalities (per 100 million vehicle miles);
  15. Annual maintenance costs (dollars per mile);
  16. Average cost of pollution damage (dollars per 1000 vehicle-miles); and
  17. Percent of total VMT on roads not meeting the user specified thresholds.

The user may specify condition thresholds for the following properties:

  • pavement condition (PSR);
  • peak-hour volume/capacity ratio;
  • lane width;
  • right-shoulder width;
  • shoulder type;
  • surface type;
  • horizontal alignment; and
  • vertical alignment.

The initial page of output in this format presents the conditions at the beginning of the analysis period. It also includes the date and time the run was executed, the number of center-line miles, and the number of sections in the sample.

For each funding period, HERS produces a page of output summarizing conditions at the end of the period. This is followed by a page summarizing the changes in conditions which occurred during the funding period. This second page of output also shows the (incremental) benefit-cost ratio of the last improvement selected. If a constraint was placed on available funds, this page also displays the amount of funds spent; while, if a performance goal was specified, it compares the performance level achieved with the specified goal.

HERS produces a similar summary of the change in conditions during the overall analysis period.

8.1.2 The Deficiency Summary Output Format

These pages, four for each funding period plus four for the overall period, provide a detailed picture of the deficiencies present on the system and the effectiveness of improvements in reducing the deficiencies. The pages are presented in pairs: the first page lists the deficiencies as percent of vehicle miles travelled; the second lists the deficiencies as a percentage of center-line miles. These pages include data for all sections in the system whether improved or not.

For the first funding period, a pair of pages describes system deficiencies at the start of the overall analysis period. Then, and for each subsequent funding period, two pairs of pages describe deficiencies at the end of the period, and changes in deficiencies during the funding period. Finally, a pair of pages describes changes in deficiencies over the entire analysis period.

The format provides statistics for nine deficiencies by functional class with rural, urban, and overall totals. Each deficiency is measured at a minimum of three levels, as presented in Table 8-1. HERS uses deficiency levels from the DLTBLS.DAT input file. While many of the levels are the same as those used in evaluating section deficiencies for possible improvement, others are specified solely for the purpose of accumulating these output statistics. HERS labels these levels as USTn, where UST represents "User Specified Threshold" and n distinguishes between multiple levels.

Table 8-1. Deficiency Levels in Output
Deficiency Threshold Operation Levels
IRI % above specified threshold UST1 - User specified threshold 1
UST2 - User specified threshold 2
UST3 - User specified threshold 3
UST4 - User specified threshold 4
UST5 - User specified threshold 5
PSR % below specified threshold UL - Unacceptable level
RL - Reconstruction level
DL - Deficiency level
UST1 - User specified threshold 1
UST2 - User specified threshold 2
V/C Ratio % above specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
WS - Widening standard
Lane Width % below specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
Shoulder Width % below specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
Shoulder Type % below specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
Surface Type % below specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
Horizontal Alignment % below specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
Vertical Alignment % below specified threshold UL - Unacceptable level
DL - Deficiency level
UST1 - User specified threshold 1
8.1.3 The "By Improvement Type" Output Format

HERS produces the bulk of each funding period's pages of printable output in this format. Each page contains a pair of tables: the upper table contains statistics for all sections improved during the funding period, while the lower table contains statistics for only those sections whose improvements included re-aligning all or a portion of the section. Statistics for sections included in the lower table are also included in the upper.

These pages do not include statistics on or derived from sections not improved during the funding period.

This format is organized by functional class versus improvement type. The lowest level of reporting is for a particular improvement type on a specific functional class (for example, statistics regarding resurfacing with shoulder improvements on rural major collectors). The user selects which pages are to be included in the printable output via switches in the RUNSPEC file. A subset of these pages is also available for the overall analysis period, as noted in the paragraphs below.

Generally, for sections with lanes added at high cost, all statistics for that section are tabulated as if all the added lanes were added at high cost. This is done even for those sections in which some lanes are added at normal cost while others are added at high cost. (The cost of adding the lanes is calculated to use different improvement costs - see Chapter 6.) The exception is the lane-miles Added output page.

8.1.3.1 The Total Initial Cost of Selected Improvements

This page summarizes the capital cost of all implemented improvements. For each section being improved, HERS first determines the cost per mile as detailed in Chapter 6. HERS then multiplies the cost by the section length (SLEN) and the expansion factor (EXPFAC) to calculate the full cost of the improvement. HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly.

This page is also available for the overall analysis period.

8.1.3.2 Initial Cost of Preservation Improvements

This page enumerates the amount of capital investment HERS specified for the preservation of existing highways. This includes all the funds used for the reconstruction, resurfacing, alignment improvement, and shoulder improvements of existing lanes. For details, see section 6.5, "Allocating Capacity and Preservation Costs," page 6-8.

This page is also available for the overall analysis period.

8.1.3.3 Initial Cost of Capacity Improvements

This page lists the capital investment HERS allocated to the expansion of capacity. It includes the cost of adding lanes and the incremental cost of widening existing lanes. For details, see section 6.5, "Allocating Capacity and Preservation Costs," page 6-8.

This page is also available for the overall analysis period.

8.1.3.4 Lane-Miles Improved

This page summarizes the lane-miles improved. For each section being improved, HERS determines the lane-miles as the number of through lanes (TLANES after improvement) multiplied by the section length (SLEN) and the expansion factor (EXPFAC). HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly.

This page is also available for the overall analysis period.

8.1.3.5 Lane-Miles of Mandatory Improvements Selected on a Priority Basis To Address Unacceptable Conditions

This page summarizes the lane-miles improved only on sections where the improvement was implemented to correct an unacceptable condition. As discussed in paragraph 4.2.3.5, the criteria for selecting these improvements are the correction of extremely poor highway conditions, and these improvements are not subjected to the benefit-cost test. (In HERS, statistics pertaining to mandatory improvements selected to address unacceptable conditions are collected only for improvements that are not replaced by a more aggressive non-mandatory improvement selected on the basis of its benefit-cost ratio.) The calculation of lane-miles is the same as above: the number of through lanes (TLANES after improvement) multiplied by the section length (SLEN) and the expansion factor (EXPFAC). HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly. The mileage shown on this page is included in the lane-miles Improved page.

This page is also available for the overall analysis period.

8.1.3.6 Lane-Miles of Non-Mandatory Improvements Not Selected on a Priority Basis

This page summarizes the lane-miles improved only on sections where the improvement was not implemented to correct an unacceptable condition. For a model run where the user did not stipulate mandatory improvements, this page presents the same data as the lane-miles Improved page. If mandatory improvements are stipulated, this page presents the differences between the lane-miles Improved page and the lane-miles of Mandatory Improvements page. (That is, the values on this page added to their corresponding values on the lane-miles of Mandatory Improvements page will equal those on the lane-Miles Improved page - with some small differences due to rounding.) For each section being improved, HERS determines the lane-miles as the number of through lanes (TLANES after improvement) multiplied by the section length (SLEN) and the expansion factor (EXPFAC). HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly.

This page is also available for the overall analysis period.

8.1.3.7 The Net Present Value of the Residual Value of All Improvements

[ This would be changed to "NPV of RSL" except that we're not doing the page at all now in the National baseline as of December 2003. ]

8.1.3.8 The Average Benefit-Cost Ratio of Selected Improvements

This page presents the average BCRs for all implemented improvements. The BCRs reported are calculated against the unimproved base case for each section over an analysis period determined by the methodology explicated in paragraph 7.3. The average BCRs are weighted by improvement cost.

This page is also available for the overall analysis period.

8.1.3.9 Total Benefits in the Last Year Of The Period

On this page HERS totals user benefits (travel time savings, operating cost savings, and safety benefits) and maintenance cost savings during the last year of the period. Benefits due to savings in emissions costs are not included on this page.

8.1.3.10 Maintenance Costs Savings in the Last Year Of The Period

The HERS procedure for estimating pavement maintenance costs (see paragraph 5.7) is based upon the deterioration of pavement from an initial PSR to a final PSR without regard to the time period involved. When estimating the savings in maintenance costs on an improved section at the end of the current funding period, HERS uses the difference between the end-of-period maintenance costs of the improved and unimproved instances of the section. HERS calculates these values based upon the decline in PSR between the middle of the first and second funding periods; that is, during the initial benefit-cost analysis period (BCAP; see section 2.9, "HERS Time Frames," page 2-13). HERS assumes that maintenance costs increase linearly during the HERS-ST Technical Report Printed Output August 2005 8-7 BCAP, and that the middle year of the BCAP (which is the last year of the funding period) incurs the average cost (that is, one-fifth of the costs of a five year period).

The maintenance costs are stored as dollars per center-line mile. To calculate the maintenance cost savings in the last year of the funding period, HERS subtracts the maintenance cost for that year after improvement from the maintenance cost for that year before improvement. The savings is expanded by multiplying by the section length (SLEN) and the expansion factor (EXPFAC).

8.1.3.11 User Benefits in the Last Year Of The Period

This page totals the benefits to users of implemented improvements. User benefits include travel time savings, operating cost savings, and safety benefits (which in turn includes the cost of fatalities, injuries, and property damage). The totals on this page will equal the sum of their corresponding entries on those pages (allowing for differences due to rounding).

8.1.3.12 Travel Time Savings in the Last Year Of The Period

This page summarizes the monetarized savings to highway users due to reductions in time spent travelling on improved sections. The (per-section) savings are calculated as the difference between the travel time costs without improvement less the travel time costs following improvement:

Eq. 8.1

TTS = (TTCu TTCi) × AVMTu +
  (TTCu TTCi) × (AVMTi AVMTu)
  2

where

TTS = travel time savings on the section;
TTCn = travel time cost in dollars per vehicle mile on the unimproved section u or the improved section i (see paragraph 5.5, "Travel Time Costs"); and
AVMTn = annual VMT (daily volume × section length × expansion factor × 365) for unimproved section u or improved section i.

The pavement condition, traffic volume, speed, and costs are calculated for the end of the funding period in which the improvement was implemented, and the calculations include consumer surplus. HERS totals the per-section travel time savings by functional class and improvement type.

8.1.3.13 Operating Cost Savings in the Last Year Of The Period

This page summarizes the operating cost savings to highway users after improving a section. HERS includes fuel consumption; oil consumption; tire wear; maintenance and repair; and vehicle depreciation as operating costs. The (per-section) savings are calculated as the difference between the operating costs without improvement less the operating costs following improvement:

Eq. 8.2

OCS = (OCu OCi) × AVMTu +
  (OCu OCi) × (AVMTi AVMTu)
  2

where

OCS = operating cost savings on the section;
OCn = operating cost in dollars per vehicle mile on the unimproved section u or the improved section i (see paragraph 5.2, "Estimating Operating Costs"); and
AVMTn = annual VMT (daily volume × section length × expansion factor × 365) for unimproved section u or improved section i.

The pavement condition, traffic volume, speed, and costs are calculated at the end of the funding period in which the improvement was implemented, and the calculations include consumer surplus. HERS sums the operating cost savings by improvement type and functional class.

8.1.3.14 Safety Benefits in the Last Year Of The Period

This page summarizes monetarized safety benefits to highway users after improving a section. As safety costs HERS includes the cost of fatalities; the cost of injuries; and the cost of property damage. HERS computes the (per-section) benefits as the difference between the safety costs without improvement less the safety costs following improvement:

Eq. 8.3

SB = (SCu SCi) × AVMTu +
  (SCu SCi) × (AVMTi AVMTu)
  2

where

SB = safety benefits on the section;
SCn = safety costs in dollars per vehicle mile on the unimproved section u or the improved section i (see paragraph 5.3, "Safety Costs"); and
AVMTn = annual VMT (daily volume × section length × expansion factor × 365) for unimproved section u or improved section i.

HERS calculates the pavement condition, traffic volume, speed, and costs at the end of the funding period in which the improvement was implemented, and the calculations include consumer surplus. HERS sums the operating cost savings by improvement type and functional class.

8.1.3.15 Crashes Avoided in the Last Year Of The Period

On this page HERS lists the number of crashes avoided in the last year of the funding period on improved sections. The data does not include information on sections which HERS did not improve during the funding period.

8.1.3.16 Injuries Avoided in the Last Year Of The Period

This page summarizes the number of injuries avoided in the last year of the funding period on improved sections. Only sections HERS improved during the funding period are included in the totals.

8.1.3.17 Lives Saved in the Last Year Of The Period

On this page HERS totals the number of lives saved in the last year of the funding period on improved sections. HERS does not include data from unimproved sections.

8.1.3.18 VMT For Improved Sections in the Last Year Of The Period

This page totals the annual vehicle miles travelled on improved sections during the last year of the funding period.

8.1.3.19 Emissions Costs Savings in the Last Year of the Period

This page tabulates the emission cost savings on improved sections during the last year of the funding period. HERS calculates the savings on a section as:

Eq. 8.4

EMCBen = (EMCu EMCi) × VMTu
  EMCi × (VMTi VMTu)

where:

EMCBen = emission cost savings;
EMCn = emission cost per vehicle mile of travel on the unimproved section u or the improved section i (see paragraph 5.8, "External Costs" for details);
VMTn = vehicle miles traveled in the last year of the funding period on the unimproved section u or the improved section i.

Note that HERS regards the cost of emissions on additional trips on the section (as a result of a lower user price due to the improvement) as a disbenefit, and subtracts it from benefits realized through the reduction of emissions on existing trips.

8.1.3.20 Miles Improved

This page summarizes the center-line miles improved. For each section being improved, HERS calculates the center-line miles as the section length (SLEN) multiplied by the expansion factor (EXPFAC). HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly.

8.1.3.21 Miles of Mandatory Improvements Selected on a Priority Basis To Address Unacceptable Conditions

This page tabulates the center-line miles improved only on sections where the improvement was implemented to correct an unacceptable condition. As discussed in paragraph 4.2.3.5, the criteria for selecting these improvements are the correction of extremely poor highway conditions, and these improvements are not subjected to the benefit-cost test. (In HERS, statistics pertaining to mandatory improvements selected to address unacceptable conditions are collected only for improvements that are not replaced by a more aggressive non-mandatory improvement selected on the basis of its benefit-cost ratio.) The calculation of center-line miles is: the section length (SLEN) multiplied by the expansion factor (EXPFAC). HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly. The mileage shown on this page is included in the Miles Improved page.

8.1.3.22 Miles of Non-Mandatory Improvements Not Selected on a Priority Basis

This page totals the center-line miles improved only on sections where the improvement was not implemented to correct an unacceptable condition. For a model run where the user did not stipulate mandatory improvements, this page presents the same data as the Miles Improved page. If mandatory improvements are stipulated, this page presents the differences between the Miles Improved page and the Miles of Mandatory Improvements page. (That is, the values on this page added to their corresponding values on the Miles of Mandatory Improvements page will equal those on the Miles Improved page - with some small differences due to rounding.) For each section being improved, HERS determines the center-line miles as the section length (SLEN) multiplied by the expansion factor (EXPFAC). HERS categorizes the datum by the improvement type and functional class and accumulates it accordingly.

8.1.3.23 Lane-Miles Added to the System through Widening Improvements

This page summarizes the lane-miles added to the system as a result of improvements which add lanes. It does not include mileage from widening existing lanes.

Because only four improvement types result in added lane miles, the format of this page is abbreviated: the improvement types which do not add lanes are not included in the format. This page also departs from the usual practice in that it allocates the lane-miles added between high and normal cost based upon the status of the individual lanes. For example, consider a section that was resurfaced and had four lanes added, two at normal and two at high cost. The HERS improvement type is "Major Widening with High Cost Lanes," and the statistics for the section (costs, miles improved, last year of period) are grouped with other sections of the same improvement type. On the lane-miles Added page, however, HERS allocates the added lane-miles evenly between the Major Widening with High Cost Lanes and Major Widening with Average Cost Lanes categories.

8.1.4 The "By IBCR" Output Format

HERS produces up to four printable summary sets in this format.1 The data is organized by functional class versus improvement type, and, within each improvement type, by incremental BCR range. Therefore, where the "by improvement type" format might show that HERS identified 4.542 billion dollars of resurfacing improvements for rural major arterials, the "by IBCR" format could show that 1.261 billion dollars were invested in improvements with BCRs greater than or equal to 6.0. HERS uses the following BCR ranges:

  • 1.0 - 1.2;
  • 1.2 - 2.0;
  • 2.0 - 3.0;
  • 3.0 - 4.0;
  • 4.0 - 5.0;
  • 5.0 - 6.0; and
  • 6.0

The four summary sets are:

  1. Capital requirements (initial cost);
  2. Number of sample sections improved (including duplicates);
  3. Miles improved; and
  4. Travel time benefits expressed as a percentage of total user benefits.

There is no comma-delimited output in this format.

8.2 Comma-Delimited Files

The HERS-ST GUI makes extensive use of the comma-delimited files, loading the output into databases for use in generating user-customizable outputs. HERS-ST generates the two files in formats which mimic the Systems Conditions Output pages and the By Improvement Type output pages.


1. For this format, to refer to "pages" would be somewhat misleading, as each summary set requires more than two physical pages to print.


For the Systems Conditions Output pages, HERS creates an output file named [RUNNUM].SS1 (where the file name is the same as the run number entry in the RUNSPEC file) which contains the comma-delimited version of this format. HERS generates a "page" for the initial system conditions and the conditions at the end of each funding period. Each page contains only the sixteen data items listed above (i.e., not the number of center-line miles, sections in the sample, etc.).

For the By Improvement Type pages, HERS creates the file [RUNNUM].SS2 to hold the comma-delimited output for selected pages of output using this format. The comma-delimited format includes only the "all improvements" set of statistics: it does not include the data for improvements with improved alignment. (That is, it only includes the top half of each output page.) The comma-delimited output set contains per funding period and overall analysis period statistics for the following pages:

  • initial cost of selected improvements;
  • initial cost of preservation improvements;
  • initial cost of capacity improvements;
  • lane-miles improved;
  • miles improved;
  • lane-mile added; and
  • the average benefit-cost ratios of selected improvements.

8.3 Section Output Files

In addition to the conventional HERS output, for each funding period (FP), HERS-ST produces a comma-delimited ASCII file describing the condition of each section at the end of the FP along with information about all improvements that have been selected and the effects of these improvements. The file describing conditions at the end of FP nn is called SECNSnn.OUT. The first record of the file contains the final year of the FP. The second contains the user's description of the run. The third record contains a set of column headings shown in Table 8-2; and the remaining records contain descriptions of all sections, in comma-delimited format, as listed in Table 8-2 and described below.

The first data item in each record contains the record number of the HPMS file containing the original description of the section. This number may be useful in locating the record.

Items 2 - 7 contain additional identification of the section being improved. These items are obtained from the corresponding HPMS record.

Items 8 - 14 identify deficiencies that will exist by the end of the FP if the section is not improved. Four of these items (PSR, lane width, shoulder type, and right shoulder width) correspond to items in the HPMS file. Volume/capacity (v/c) ratio (Item 8) is HERS' estimate of the ratio of design-hour volume to peak-period hourly capacity. Horizontal and vertical alignment adequacy (Items 12 and 13) are either derived from information supplied on curves and grades by class, or they are obtained from the input values for horizontal and vertical alignment adequacy. In both cases, they use the HPMS codes for alignment adequacy. A simplified description of these codes2 is:

Table 8-2. Record Format and Column Headings of SECNSnn.OUT Files
Field Column Heading Data Type
Section Identification
1. Record number RECNO Integer
2. County code CNTY Integer
3. Section identification SECID Character
4. Sample identifier SAMPID Character
5. LRS identification LRSID Character
6. LRS beginning point BEGMP Floating Point
7. LRS ending point ENDMP Floating Point
Deficiencies
8. PSR PSR0 Floating Point
9. Volume/Capacity ratio VCR0 Floating Point
10. Lane width LW0 Integer
11. Shoulder type SHLT0 Integer
12. Right shoulder width RSHLW0 Integer
13. Horizontal alignment adequacy HORA0 Integer
14. Vertical alignment adequacy VERA0 Integer
Improvement
15. Improvement type ITYPE Integer
16. Lanes added LADD Integer
17. Increase in capacity CAPINC Floating Point
18. Type of selection TYPSEL Integer
19. BCR BCR Floating Point
Characteristics at End of FP
20. Volume/Capacity ratio VCR Floating Point
21. Average speed SPD Floating Point
22. PSR PSR Floating Point
23. IRI (inches/mile) IRI Floating Point
24. Total lanes TLAN Integer
25. Peak lanes, peak direction PLAN Integer
26. Peak lanes, opposite direction CPLAN Integer
27. Peak capacity, peak direction PCAP Floating Point
28. Peak capacity, opposite direction CPCAP Floating Point
29. Off-peak capacity OPCAP Floating Point
30. Access control ACCESS Integer
31. Lane width LWID Integer
32. Shoulder type SHLT Integer
33. Right shoulder width RSHLW Integer
34. Median type MEDT Integer
35. Median width MEDW Integer
36.Widening feasibility WFEAS Integer
37. Horizontal alignment adequacy HORA Integer
38. Vertical alignment adequacy VERA Integer
39. AADT AADT Floating Point
40. Emissions costs EMC Floating Point
Costs and Benefits
41. Improvement cost IMPC Floating Point
42. Emissions benefits EMB Floating Point
43. Travel-time benefits TTB Floating Point
44. Operating-cost benefits OPCB Floating Point
45. Safety benefits SAFB Floating Point
46. Total benefits TOTB Floating Point
State Control Field
47. State control field SCF Character
  1. All curves (or grades) meet design standards.
  2. Some curves (or grades) do not meet design standards, but they do not affect speed or safety.
  3. Infrequent curves (or grades) affect speed or safety.
  4. Several curves (or grades) affect speed or safety.

The next five items (15 through 19) describe the improvement that is finally selected for the section, if any. If one or more potential improvements are identified but none are selected, these items describe the rejected improvement with the highest BCR. If no potential improvement is evaluated in this FP, these items are blank. The use of these items when an improvement is selected is described below:

  • Improvement type. A code identifying the type of improvement. The codes used for the improvement types that can be generated in basic runs are shown in the last two columns of Table 8-3. As discussed in section 4.1 "The Override Mode and User-Specified Improvements" on page 4-1, in override runs, the HERS-ST user may introduce additional codes to represent other types of (user-specified) improvements. The improvement types shown in Table 8-3 are the only ones analyzed by the National HERS system. In section 4.1 "The Override Mode and User-Specified Improvements" on page 4-1, these improvement types are referred to as "HERS-type" improvements.
    Table 8-3. Codes for "HERS-Type" Improvements
    IMPRCOST Code Improvement Code
    Without Alignment Improvement With Alignment Improvement
    Rs Resurface 1 11
    RsSh Resurface and improve shoulders 2 12
    MinW Resurface and widen lanes (minor widening) 3 13
    MWNC Resurface and add normal-cost lanes (major widening) 4 14
    MWHC Resurface and add high-cost lanes 5 15
    RC Pavement reconstruction 6 16
    RCWL Pavement reconstruction with wider lanes 7 17
    RCNC Pavement reconstruction and add normal-cost lanes 8 18
    RCHC Pavement reconstruction and add high-cost lanes 9 19
  • Lanes added is the number of lanes added by the improvement (if any).
  • Increase in capacity. The increase in peak-period peak-direction capacity (if any) produced by this improvement.
  • Type of selection. This field identifies the roles played by HERS-ST and the user in the improvement selection process. Table 8-4 presents the codes used by HERS-ST. (It should be noted that HERS-ST produces information about some improvements that were not selected.)
  • BCR. Normally, the BCR of the improvement is the discounted present value (at the time of improvement implementation) of the sum of the user and agency benefits of the improvement divided by the implementation costs. An exception occurs when the system is operating under a funding constraint or with a performance goal (i.e., when objective type is 1 or 2) and two (or more) alternative improvements are provisionally selected for a section in sequence. In this case, the BCR of the improvement is an incremental BCR; i.e., it is derived from the incremental benefits and costs of choosing the improvement that is finally selected to replace the last previous improvement that had been provisionally selected.

2. More formal descriptions of the alignment adequacy codes are contained in FHWA, Highway Performance Monitoring System Field Manual, December 1999, pp. IV-31 and IV-32.


The next 21 items describe the section at the end of the FP. Items 22 - 25, 27, 30 - 36, and 39 correspond to items in the HPMS file. Items 20, 37, and 38 correspond to Items 9, 13, and 14 of the SECNSnn file and are described above. Items 21 and 40 are the program's estimates of: the overall average speed on the section (in mph); and the external costs of emissions in the last year of the FP generated by vehicles using the section (in thousands of dollars). Item 39 is HERS' estimate of AADT at the end of the FP.

Table 8-4. Type of Selection Codes
Code Interpretation
1 Improvement was evaluated by HERS-ST but not selected.
2 Improvement was selected by HERS-ST.
3 Improvement was specified by user. (User requested HERS-ST not to add additional options).
4 Improvement was requested by user; HERS-ST did not find any cost- effective options to add.
5 Improvement combines options requested by user with options added by HERS.
6 Improvement combines a HERS-ST selection for this FP with a Table 8-3 Type 1, 2, or 6 improvement requested by the user for a subsequent FP.

Item 26 is the number of "counter-peak" lanes; i.e., the number of peak-period lanes in the "non-peak" direction. This value is usually obtained by subtracting the number of peak lanes in the peak direction (Item 25) from the total number of (off-peak) through lanes (Item 24). However, for some sections, HERS infers the likely existence of extra peak-period lanes resulting from parking restrictions or use of shoulders as travel lanes during the peak period. For these sections, total peak lanes (Items 25 and 26) will exceed (off-peak) through lanes (Item 24). For rural sections with less than four lanes, "peak" lanes represent the total number of lanes in both directions, and counter-peak lanes equals zero.

Corresponding to peak, counter-peak, and through lanes are three values of capacity: peak, counter-peak, and off-peak capacity (Items 27 - 29). For rural roads with less than four lanes, the peak and off-peak capacities are two-way capacity, and counterpeak capacity is zero. For all other roads, the three capacities are one-way capacities. Peak capacity is the capacity coded in the HPMS record. Off-peak and counter-peak capacities may be equal to or smaller than peak capacity.

The next part of the record contains information about the costs and benefits of any improvement. The first of these fields contains improvement costs (in thousands of dollars) supplied by the user (see section 3.1.2, "User-Specified Improvements Data File," page 3-4) and/or estimated by the program (see Chapter 6; for special considerations regarding the cost calculations of improvements which combine a user-specified improvement with a HERS improvement, see section 4.1.3.1, "Improvement Costs," page 4-5).

When section-specific estimates of improvement costs for a specific improvement are supplied by the user, these costs are used for that improvement. If the program chooses to combine this improvement with an additional widening option and/or an alignment improvement, the incremental cost of these options are estimated and added to the total.

The next five fields are the program's estimates of the user and external benefits of the improvement in the last year of the FP, in thousands of dollars. Separate estimates are provided of the benefits of reductions in emissions costs, travel time, operating costs, and crash costs, along with the sum of all four types of benefits. Negative values in the fields for emissions benefits or safety benefits indicate an estimated increase in emissions or safety costs. For improvements that are estimated by the program to result in increased use of the section, estimated benefits include the benefits to new users of the section (estimated per new vehicle to equal half the per-vehicle benefits to old users). If no potential improvement is evaluated in the FP, these fields are blank.

The final field of the record reproduces the contents of the State Control Field (Field 8 of the HPMS record).

The system user may find it useful to read the SECNSnn.OUT files into Excel. Attempting to open any of these files in Excel results in entering Excel's Text Import Wizard. After entering this subsystem, the user should choose "Delimited" in Step 1, and choose only "Comma" in Step 2. In Step 3, the Format should be set to "Text" for Columns 3 - 5 and 473 and left as "General" for all other columns.4 The imported file will contain: the final year of the FP on Line 1; the user's description of the run on Line 2; and a set of column headings (from Table 8-2) on Line 3. To adjust all spreadsheet columns to the appropriate widths, the user should highlight the entire spreadsheet except Rows 1 and 2 and then ask Excel to select the appropriate column widths (Format, Column, AutoFit Selection).

The HERS-ST GUI also provides advanced tools for the viewing, sorting, and presentation of this data.


3. Scrolling down two lines will cause Columns 1 - 6 to appear in the Data Preview. Column 47 can be reached by scrolling to the right.

4. The Text Import Wizard can be bypassed by changing the file type to CSV before reading the file into Excel. This alternative is simpler, but it assigns "General" format to all columns. If Columns 3, 4, or 46 have any cells that contain only numeric characters, "General" format will result in interpreting the contents of these cells as numbers, an interpretation that may not always be desirable.


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Updated: 02/14/2013