Economic Analysis of Council Bluffs and Keg Creek ABC Projects

slide 1: Economic Analysis of Council Bluffs and Keg Creek ABC Projects

Suri Sadasivam

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slide 2: Economic Analysis

What is the economic efficiency of accelerated bridge and roadway construction ?

How does accelerated construction compare with traditional option in terms of economic value?

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slide 3: The Concept...

Compare Costs vs Benefits for Traditional and Accelerated Construction Options

Photo of a triangular rock balancing a flat rock horizontally on the point of the triange. Two round rocks are positioned on either side of the flat rock, in balance. One rock represents agency benefits, the other represents public benefits, indicating that agencies must balance these two interests so neither outweighs the other.

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slide 4: The Steps...

Brief diagram depicting the cost elements of traditional construction, in which agency cost plus user cost equals project cost.

Brief diagram depicting the cost elements of accelerated construction, in which agency cost plus user cost equals project cost.

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slide 5: The Inputs...

Agency Costs	Road User Costs
Preliminary Design and Engineering Construction Costs Equipment Material Construction labor Mobilization Incentives/disincentives Construction Engineering Traffic control Law Enforcement	Delay costs Vehicle operating costs Crash costs Emission costs

Plus project duration

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slide 6: Compare the Alternatives

When weighing traditional construction costs against accelerated construction costs, total project cost for traditional construction is less than the total project cost for accelerated construction.

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slide 7: Improvements to the 24th Street – I-29/80 Interchange in Council Bluffs, Iowa

Economic Analysis

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slide 8: 24th Street – I-29/80 Interchange (Council Bluffs, IA)

KEY INNOVATION

Use of full-depth, precast bridge deck panels made with self-consolidating, high- performance concrete
Estimated construction duration
- Cast in-place → 426 days (two seasons)
- Precast → 175 days (less than one season)

Google map overlaid with a satellite map of the project area.

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slide 9: 24th Street – I-29/80 Interchange (Council Bluffs, IA) Agency Costs

Category	Cast in place	Precast	% Increase
Preliminary design and engineering	$304,380	$516,032	70%
Bridge construction	$5,073,000	$6,450,398	27%
Roadway improvements	$4,807,721	$4,807,721	-
Traffic control	$272,521	$272,521	-
Construction inspection	$50,730	$70,954	40%
Miscellaneous	$620,512	$388,636	-37%
Total	$11,128,864	$12,506,262	12.4%

Increase in agency cost with precast option was $ 1.4 Million

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slide 10: 24th Street–I-29/80 Interchange (Council Bluffs, IA) Road User Costs –Delay Costs

Total delay time due to work zone = 607 vehicle-hours / day

Iowa DOT estimates = $8/hr for cars and $ 24/hr for trucks

Daily RUC due to work zone = $ 6,215.68

Category	Cast in Place	Precast
Delay time due to work zone	No difference	No difference
Number of Construction Days	426 (2 seasons)	175 (< 1 season)
Total Delay Costs	$2,647,880	$1,087,744

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slide 11: 24th Street – I-29/80 Interchange (Council Bluffs, IA) Road User Costs – Data for Safety Costs

Google satellite map of the 24th Street-I-29/80 Interchange.

Million Veh. Miles	Cast in Place	Precast
I-29/80	5.96	2.45
24th street	37.64	15.46
Traffic Over Construction Period	43.60M	17.91M

Crash Rate per 1000 vehicles

Personal injury: 69

Non personal injury: 146

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slide 12: 24th Street – I-29/80 Interchange (Council Bluffs, IA) Road User Costs – Safety Costs

Category	Cast in place		Precast
Category	I-29/80	24th Street	I-29/80	24th Street
Injury-causing crash	$494,883	$59,143	$203,265	$24,312
Non-injury crash	$283,005	$41,795	$116,240	$17,181
Total	$878,826		$360,998

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slide 13: 24th Street – I-29/80 Interchange (Council Bluffs, IA) Road User Costs

Category	Cast in Place	Precast
Delay Costs	$2,647,880	$1,087,744
Vehicle Operating Cost	No difference	No difference
Crash Cost	$878,826	$360,998
Total RUC	$3,526,706	$1,448,742

RUC savings with precast option were about
$2 million

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slide 14: 24th Street – I-29/80 Interchange (Council Bluffs, IA) Total Cost Comparison

Bar graph shows the total cost comparison for cast in place versus precast broken out by agency costs and RUC. For cast in place, the cost is $14.65 million, and for precast the cost is $13.96 million.

With Precast option

Increase in agency costs = $1.38 M
Savings in RUC = $ 2.08 M
Net savings = $ 700,000

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slide 15: Reconstruction of US 6 bridge over Keg Creek, Iowa

Economic Analysis

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slide 16: Reconstruction of US 6 Bridge over Keg Creek

KEY INNOVATION

Use of Prefabricated substructure and modular superstructure elements
Estimated construction duration
- Cast in-place → 183 days (6 months)
- Precast → 14 days

Map of the project area with the detour route and location of the bridge closure identified.

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slide 17: Reconstruction of US 6 Bridge over Keg Creek – Agency Costs

Item	Baseline Case	As-Built Case
Bridge	$1,147,178	$2,294,472
Road Improvements	$305,967	$305,967
Traffic Control	$3,200	$3,200
Concrete Flume	$55,185	$55,185
Total Project	$1,511,530	$2,658,823

Increase in agency costs with precast option was $1.15 Million

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Traffic control includes the detour signage which is assumed to be the same for the as-built and baseline scenarios.

slide 18: Reconstruction of US 6 Bridge over Keg Creek – Road User Costs – Vehicle Operating Cost

Trucks only (9% of AADT) ~ 350 trucks

21 mile detour

Mileage costs for trucks = $ 0.81 /mile

Daily RUC due to work zone = $ 5,955.20

Category	Cast in Place	Precast
Detour Length	No difference	No difference
Number of Construction Days	183	14
Total VOC	$1,089,802	$83,373

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The VOC can be estimated conservatively by considering only commercial vehicles (light and heavy trucks) traveling the designated route due to weight restrictions on other county roads in the area.

Passenger vehicles are discounted from the VOC calculation because there are numerous county roads which could serve as non-planned detour routes preventing an accurate traffic estimation based solely on the AADT on US 6.

slide 19: Reconstruction of US 6 Bridge over Keg Creek – Road User Costs – Delay Costs

21 mile detour for trucks only (9% of AADT)

Additional travel time due to detour = 24.67 min /truck

Value of delay time = $ 25.67/hr for trucks

Daily RUC due to work zone = $ 3,684.70

Category	Cast in Place	Precast
Delay time due to work zone	No difference	No difference
Number of Construction Days	183	14
Total Delay Costs	$674,300	$51,586

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As with the VOC calculation, only delay costs occurred by commercial vehicles were considered since passenger vehicles could have chosen an alternate detour route.

$25.67 is based on Mallela and Sadasivam, Work Zone Road User Costs Concepts and Applications, 2011. Report No. FHWA-HOP-12-005, Federal Highway Administration.

slide 20: Reconstruction of US 6 Bridge over Keg Creek – Road User Costs

Category	Cast in Place	Precast
Delay Costs	$674,300	$51,586
Vehicle Operating Costs	$1,089,802	$83,373
Crash Cost	No difference	No difference
Total RUC	$1,764,102	$134,959

RUC savings with precast option were about $1.63 million

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slide 21: Reconstruction of US 6 Bridge over Keg Creek – Total Cost Comparison

Bar graph shows the total cost comparison for cast in place versus precast broken out by agency costs and RUC. For cast in place, the cost is $3.275 million, and for precast the cost is $2.793 million.

With Precast option

Increase in agency costs = $1.147 M
Savings in RUC = $ 1.629 M
Net savings = $ 481,850

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