Answer 2Part B:

In the research paper the author described the cost in four functional forms. The treatments considered by the author were thin HMA overlay, micro surfacing, structural HMA overlay, functional HMA overlay and resurfacing (partial 3R). The best functional form for each treatment on the basis of their statistical performance that is goodness of fit was selected. The model was validated by using two different model validation methods that are mean squared prediction error (MSPR) and validation plots. In the first one the data was divided into two datasets of 80% and 20%. The 80% of the data was used for calibration and 20% for validation of model. The MSPR calculated was compared with mean square error (MSE). The model with closest MSPR and MSE values is the best one. In the second method the observed costs and predictive costs obtained by models were plotted. The models having predictive costs closest to the 100% validation line are considered to be the best.

Part A:

There exists a linear relationship between cost and explanatory variables in the average cost estimation approach. This linearity does not take into account any economies of scale. In the cost functional form, explanatory variables are set free to take any non-linearity involved in the cost function. Explanatory variable are not restricted to unity rather they are free to determine any statistical estimation. These features make explanatory variables as indicative of scale or condition of economies.

Part C:

For analyzing the bridge rehabilitation cost the explanatory variable may include age of bridge, height of deck slab, width of bridge, length of bridge and traffic loading on the bridge.

Answer 3To calculate user cost associated with work zoneFor auto speed reduction from 65mph to 40 mphFor trucks speed reduction from 55mph to 40 mph Length of work zone is 5 miles Travel time value for trucks $28/ hrTravel time value for autos $18/ hrTraffic volume 12500(40% are trucks and 60% are autos)

Difference for travel time of autos= ∆T =140

− 165

=.0096hr /mile

Difference for travel time of trucks= ∆T =1

40− 1

55=.0068hr /mile

User cost for autos=Vi∆Ti Ci=60% of 125000*.0096*18= 12960$/mile

User cost for trucks=Vi∆Ti Ci=40% of 125000*.0068*28= 9520$/mile

The user cost for 6 miles in case of autos = 12960*6= $77760The user cost for 6 miles in case of trucks = 9520*6= $57120

Answer 4

Part a

The above graph was presented by Opus Central Laboratories. From the graph the following were obtained Before improvement VOC= $.06/ VMTAfter improvement VOC= $.01/ VMTChange in VOC= $ .05/ VMTLength of expressway= 30 milesOverall change in VOC= 30*.05*365

= $547.5 million/ year

Part bThe increase in speed is from 26mph to 41 mph

R=$ 1.8 million, r=8%

∆UIC=100( .08365∗24 )( 1

26− 1

41 ) (1.8∗106 )

∆UIC=23.13 ₵/ veh-mile

Answer 5Vehicle occupancy = 1.5

Annual VMT= 2 million (before improvement)

Annual VMT = 3.5 million (after improvement)

Crash rate = 4 crashes/million (before improvement)

Crash rate = 3 crashes/ million (after improvement)

Safety savings =.5(4-3)(3.5+2)

Safety savings= $ 27.5

Safety savings per vehicle= 1.5*27.5=$4.125