appendix H – CDTC’s Merit Evaluation Procedureappendix H

Benefit/Cost Calculations

Introduction

Benefit to cost ratios are calculated by CDTC staff whenever possible. They are shown in the box in the upper right-hand corner of the project fact sheet. Consistent units of thousands of current dollars per year are used throughout. Instances where a benefit/cost ratio calculation is inappropriate or unable to be calculated are handled by further elaboration of the "non-quantifiable" or "qualitative" project benefits. Bicycle and pedestrian projects are handled differently, as explained below.

Five measures of project benefit are calculated, including safety, travel time, energy/user, and "other" benefits. Life cycle cost savings are applied primarily to infrastructure improvements. Life cycle cost savings are calculated by using the CDTC STEP Model to estimate the system traffic disbenefits of letting a bridge or pavement section deteriorate to the point of abandonment.

Safety Benefits

Safety benefits are measured in the dollar value of the projected reduction in accidents per year. They are the product of the average annual accidents, the expected percent reduction in accidents as a result of the improvement and a monetary equivalence factor from a standardized table developed by NYSDOT.

Using ArcView GIS and linked data from NYSDOT, accident data were obtained for each of the candidate project segments for the four-year period of 1998 through 2001 for state roads and the three-year period of 1998 through 2000 for non-state roads. For projects proposed on New York State roads the State Accident Surveillance System (SASS) data files were used; for those proposed on non-state roads the Centralized Local Accident Surveillance System (CLASS) files were used.

Accident Reduction Factors

Accidents were identified as intersection or link related, or in the case of projects proposing to realign curves, curve-related link accidents. Motor vehicle only accidents were distinguished from motor vehicle/pedestrian or motor vehicle/bicycle accidents. Improvements had reduction factors for roads with AADT's greater than 5,000 per lane and those with less. The majority of accident reduction factors used in this analysis were obtained from NYSDOT and are found in Table H-1 on page H-3. Supplemental accident reduction factors were obtained from other sources and are found in Table H-1A on page H-7.

Accident reduction factors were separated into various groups: those that could be applied project-wide against link accidents, those that could be applied project-wide against intersection accidents, those to be applied at distinct locations within the project limits (i.e. curves) and those that could be applied against bicycle/motor vehicle or pedestrian/motor vehicle accidents only. Examples of project wide accident reduction factors include drainage improvements or shoulder widening. Intersection channelization or realignment of horizontal curves are factors related to intersections or distinct locations.

Application of Accident Reduction Factors

Information regarding planned improvements to be undertaken for each proposed project was obtained from the Project Justification Packages submitted to CDTC. Project improvements for which an applicable accident reduction factor was available were then identified and corresponding average accident reduction factors tallied. For the vast majority of projects, more than one accident reduction factor was applicable. In these cases, the average was applied, consistent with methodology used by NYSDOT to estimate the potential safety benefits of projects.^[1] The estimated number of accidents reduced annually for each component (intersections, links, bicycle, and pedestrian accidents) was calculated and a grand total for the project produced. Safety benefits were then calculated by multiplying the average annual accident cost by the number of accidents reduced.

Accident Costs

Average annual accident costs for all facility types were supplied by NYSDOT^[2]. These averages were then aggregated into one average for all urban facility types and one for rural facility types as shown in Table H-2 on page H-8. Costs are not segregated by the type of damage (fatality, injury, or property damage only).

Table H-1

ACCIDENT Reduction Factors

Improvement	Average Reduction (% of All Accidents) >5000 AADT/ln/<5000 AADT/ln				Remarks
INTERSECTION IMPROVEMENTS
Channelization		37/35		Right angle 58%/48%, Rear and overturn (OT) 30%/53%, Left turn 49%
Add left turn lane with physical separation		26/--		Head on/sideswipe (SS) 79%/79%
Add left turn lane with painted separation		45/50		Right-angle 63%/62%, rear-end/OT 39%/54%, left turn 35%/57%
Add right turn lane with physical separation		--/--		Limited data
Add pavement markings to reduce size of intersection		--/--		Limited data
Other channelization		24/36		Right angle 47%/45% Rear end/OT 33%/76%
Traffic Signals/Devices		19/34		Right angle 34%/50%, Rear end/OT 26%/39%, Left turn 18%/26%, Head on/SS 39%/23%
Other signal improvements		15/23		Right angle 22%/30%, Rear end/OT 25%/39%
Install stop ahead signs		15/15
4-way stop signs		73/73
Install minor leg stop control		1/1
Install yield signs		23/23
Install new flashing red/yellow signal		26/25		Right-angle 36%/35%
Change in operation to flashing red/yellow signal		--/--		Limited data
Install new red/yellow/ green signal		20/38		Right-angle 43%/74%, rear-end/sideswipe 20%/22%
Upgrade red/yellow/green signal. (Includes larger lenses, better placement of heads, phase adjustment and general signal upgrades)		19/37		Right-angle 37%/47%, rear-end/OT 26%/41%, left turn 26%/38%, Head on/SS 52%/32%
Left turn protection (change # of phases)		36/30		Right angle 56%/54%, rear end/OT 35%/27%, left turn 46%/41%
Add pedestrian signals		13/13		Detailed engineering analysis recommended
Change in signal operation, from pre-timed to traffic- actuated		28/39		Rear-end/sideswipe 26%/53%, right angle 32%/41%, Head on/sideswipe 60%/81%
Channelization & Signals/Devices		8/41		Right angle 30%/66%, rear end/OT 26%/49%
Add left-turn lane with signal (physical)		19/51		Right-angle 55%/68%, rear-end/OT 28%/50%, left turn 24%/24%
Add left-turn lane with signal (painted)		16/30		Right-angle 49%/64%
Add right-turn lane with signal		--/--		Limited data
Add left & right turn lane with signal		14/41		Right-angle 42%/70, and rear-end/sideswipe 38%/64%
Sight distance improvement		31/31
Other intersection work		--/41		Right angle /69%
Prohibit turning movement		40/40
Prohibit Parking		32/32
Cross-Sectional improvements
Pavement Widen, No Lanes Added		59/37		Left turn 69%/77%
Widen travel way from 9 feet		--/--		Limited data
Widen travel way from 10 feet		59/37		Left turn 69%/77%
Lanes Added, Without New Median		31/20		Right angle 45%/35%, Rear end/OT 52%/42%, head-on/sideswipe 44%/38%
Add additional lanes same alignment		31/20		Rear end/OT 52%/42%, head-on/sideswipe 44%/38%, right angle 45%/35%, increased right turn 79%/79%
Add climbing lane		--/--		Limited data
Divided Highway, New Flush Median		44/24		Rear end/OT 41%/44%, Left turn 78%/59%, Head on/sideswipe 57%/60%
Add flush median		52/44		Left turn 78%/72%
Add flush median with refuge for left turns		44/24		Rear-end/OT 40%/44%, head-on/sideswipe 52%/55%, left-turn 77%/58%, increased right turn 95%/95%
Widen flush median		--/--		Limited data
Shoulder Widening or Improvements		--/--		Limited data
Shoulder stabilization		--/--		Limited data
Widening existing shoulder		17/17		For 2-lane roads only
Add additional lane w/median, same alignment		20/20		General reconstruction
Skid Treatment W/Grooving		22/37		Rear end/OT 35%/54%, wet road 54%/64%, Run off the road (ROR) 40%/41%, Fixed object 19%/36%
Longitudinal grooving		21/37		54%/64% wet-road accidents, ROR 40%/41%, rear-end/OT 35%/54%, Fixed object 19%/36%
Transverse grooving		--/--		Limited data
Skid Treatment W/Overlay		20/13		Open-graded mix most effective. Right angle 23%/25%, Fixed object 34%/26%
Resurfacing with skid resistant pavement		13/8		42%/35% wet-road, right angle 23%/31%
Resurfacing and superelevation		28/28		Wet road 51%/51%
Resurfacing w/open-graded mix		75/75		Wet road 91%/91%, fixed objects 93%/93%, head on/sideswipe 90%/90%
Resurfacing w/Verglimit		31/31		Icy road 52%/52%
Side Slopes		45/43		Fixed objects 62%/62%
Flattening side slopes		45/43		Fixed objects 62%/62%
Flattening or clearing of side slopes		--/--		Limited data
Improvement and/or Replacement of Structures
Widening existing bridge or other major structure			65/65	Collision w/bridge or other major structure only
Replacement of bridge or other major structure			25/25
Construction of new bridge or major structure			19/19
Construction or improvement of minor structure			--/--	Limited data
Construction of pedestrian over or under crossing			--/--	Limited data
Other structure work			--/--	Limited data
Alignment Work
Horizontal alignment changes			41/59	Fixed object 87%/68%, ROR 79%/90%, head-on 64%/67%, Rear end/OT 24%/73%
Vertical alignment changes			--/--	Limited data
Horizontal & vertical alignment			21/20	General reconstruction
Roadside Appurtenances
Traffic signs			14/18	Rear end/OT 18%/21%, right turn 59%/--, right angle --/34%, left turn --/35%
Install/upgrade traffic signs			13/28	Right angle 33%/43%, rear end/OT 27%/33%, left turn 43%/51%
Replace standard w/large stop signs			19/19
Install/improve warning signs			--/--	Limited data
Install/improve curve warning signs			--/--	Limited data
Install/improve advance curve warning flashers			54/54	Night 62%/62%
Install/improve other signs (arrow signs)			34/34
Protection/removal of fixed object			17/18	Rear end/OT 44%/42%
Make breakaway signs or lights			32/28	Rear end/OT 70%/72%
Install clearance and/or hazard markers			--/--	Limited data
Installation/Improvement of Road Edge Guiderail			13/16	Rear end/OT 28%/36%, Fixed object 14%/16%, right angle --/17%
Replace or upgrade deficient guiderail			9/18	Guiderail 31%/40%, fixed-object 18%/23%, Rear end/OT 27%/41%, ROR 32%/42%
Protection or removal of fixed object in gore			--/--	Limited data
Install or upgrade culvert and bridge railing			20/22	Collision w/bridge or culvert 38%/37%, Rear end/OT 32%/34%
Install road edge guiderail at new location			10/10	Fixed object 4%/4%, increases collision w/guiderail 51%/67%, ROR 18%/18%, Rear end/OT 34%/31%
Removal of guiderail (w/o other improves)			(-19)/ (-19)	Increase collisions w/ditch/cut/bank 360%/411%
Installation or Improvement of Median Barrier (Physical Separation)			20/56	Right angle 53%/30%, Rear end/OT 32%/32%, Left turn 44%/44%, ROR 42%/42%
Replace deficient median barrier			--/--	Limited data
Install median barrier			19/19	Right angle 54%/58%
Install or improve median barrier near gore area			17/17	ROR 56%/56%, increases collision with guiderail 57%/57%, Rear end/OT 39%/39%
Installation of Pavement Markings and/or Delineators			9/17
Install raised snow plowable pavement markings			--/--	Limited data
No-passing striping			66/66
Centerline striping			5/5	No passing striping 66%/66%
Road edge restriping			38/44	Fixed object 59%/66%, Rear end/OT 50%/45%
Delineation of shoulders			9/9
Delineation of curves			30/30	On curves of Radius <500ft
Thermoplastic pavement markings			35/14	Fixed object 80%/56%
Thermoplastic pavement markings at spot locations			22/22	Limited data
OTHER ROADSIDE APPURTENANCES
Roadway lighting installation		9/9		Spot locations 36%/36%, nighttime 67%/67%
Improve drainage &/or drainage structures		32/32
Fencing installation		--/--		Limited data
Install impact attenuators		4/4		Limited data
Shoulder rumble strips		--/--		Limited data
Improvements at gores		31/23		Right angle 60%/51%, Rear end/OT 44%/50%, Head on/SS 43%/34%, ROR 52%/56%
Protection from fixed objects/improvement of positive guidance in gore area		35/27		Rear-end/sideswipe 45%/53%, run-off-the road 46%/46%, fixed object 18%/18%
Thermoplastic striping & delineation in gore area		94/38		Rear-end/sideswipe 64%/51%
Removal or protection of fixed objects in gore area		7/7		Rear-end/sideswipe 32%/42%, ROR 74%/84%

Source: NYSDOT Traffic Engineering and Safety Division Safety Program Management Bureau, 5/00

Table H-1A

Supplemental accident Reduction Factors

Improvement	Average Reduction (% of Accidents) >5000 AADT/ln/<5000 AADT/ln			Remarks/Source
Consolidation of driveways		20/20	NYSDOT's 1995/1996 Five-Year Program included an estimate of a 26% reduction in accidents at locations where arterial management techniques are applied including consolidating driveways, inter-connecting parking lots, installation of frontage roads, etc. Azzeh et. al reported an estimated 20% reduction in accidents after consolidation of driveways.
Installation of service roads		17/17	Wolf Road/Exit 3 Area Transportation System Study Planning Report, CDTC, March 1990
Installation of sidewalks		50/50	FHWA's Investigation of Exposure-based Pedestrian Accident Areas: Crosswalks, Sidewalks, Local Streets and Major Arterials. RD -88-038, Knoblauch, RI, Justin, BH, Smith, SA et al, 1988. Applied against pedestrian/mv accidents only
Painted and/or raised bicycle crossing at intersections - assumed to be installed with all bike lane projects		30/30	An estimated reduction of 30% in bicycle/motor vehicle accidents due to installation of raised and painted bike lane/path intersection crossing (Garder, Leden, and Pulkkinen, 1998) Applied against bicycle/mv accidents only
Traffic calming (bulb outs, etc)		40/40	Estimated 40% reduction in all intersection accidents from traffic calming aggregating for all improvement types including bulbouts, narrowings, crosswalks, etc. according to "Safety Benefits of Traffic Calming", Zein, Geddes, Hemsing, Johnson, 1997, Transportation Research Record 1578. Applied against intersection accidents only
Installation of pedestrian refuge island		57/57	Geddes et al found the following levels of accident reduction: traffic circles and chicanes, 82 % … multiple measures 65% … pedestrian refuges 57%. "Safety Benefits of Traffic Calming", Zein, Geddes, Hemsing, Johnson, 1997, Transportation Research Record 1578.
Installation of Roundabout		39/39	According to Insurance Institute for Highway Safety as published in "Crash Reductions Following Installation of Roundabouts in the United States", by Persaud, Retting, et. al., March 2000.  This figure was cited by the NYSDOT Roundabout group in a presentation made to the CDTC Policy Board in June 2004.  This 39% is a conservative number with smaller, single lane roundabouts typically achieving higher rates of reduction than large, multilane roundabouts. Aggregated over all types, the Insurance Institute also states that 76% reductions were found for all injury accidents. Reductions in the numbers of fatal and incapacitating injury accidents were estimated to be about 90%.

Table H-2

Average Accident Costs

Facility Type

Average