Registration Number Unit

Group name 1

RegistrationNumber

Unit

Principles of Transportation Engineering

Objective

Our aim was to study the Traffic behavior and investigate thetransportation engineering model of Highway 77 close to Driscoll.

Transportationengineering defines the technology and scientific applications to theplanning, functional design, operation and management of resourcesand facilities for any mode of transportation. In effect, safety,efficiency, conveniences, economy and environmental benefits wouldresult.

Figure1.Aerial view of a section of the US 77 (study site near Driscoll)

The US 77 highway isa Northern-Southern corridor way. It runs through Driscoll in NuecesCounty in the State of Texas. So, it’s the main subject for ourresearch. The highway serves as a route for local traffic in thearea. Currently, there have been projects to oversee the interstateroad standards. In our routine studies and investigations, we foundout several ideas about the highway. Day by day, the trafficincreases along the way. Hence, the need for an interstate qualityroad is a priority, in the long run. In this regard, an interstatequality road would lead to the construction of ‘frontage roads anda regulatory access to the high-speed prime travel lanes by entranceand exit ramps.’ In addition to that, the effect would beaccommodation of larger traffic flows and enhancing on traffic safetylevels (US 77 Highway Journal 8). Occasionally, an improvement wouldalso lead to mobility enhancement developing economic growth andexpanding on the flow capacity. The road also requires additionalintersection improvements. Another primary concern is the developmentof the construction of wider road shoulders and also enhance thesafety of disabled vehicles and motorists requiring to pull over tothe shoulders.

Methodology

The factors that weconsidered during the study are the time and duration of the studyand the location of study. In our research, we found out a spot thatwas close to Driscoll but not too close to a major intersection suchas the intersection between the US 77 and the road FM 665. In thatrespect, such intersections were avoided because of possibly biasedresults. Otherwise, we could have obtained misleading data sincethere might be traffic challenges at a significant intersection. Someof them are traffic snarl-ups, and that might lead to inaccuratespeed analysis lack of correct data due to the absence or presenceof a limited type of vehicle. For instance, in checking the number ofnorthbound right trucks at an intersection point, we might miss therelevant information because there is an inconsistent traffic flow.However, at a point that is further from the intersection a fastmoving road section with a consistent traffic flow, the results willbe at least genuine and valid.

We choose to take an observation at a point further from the minorintersection E Ave C road that was midway from the road FM 665.

Procedure

Ourdata collection plan was primarily sub-divided into several stages.We decided to work out through the research process using a simpleyet detailed structure. We divided our team into smaller groupnumbers. Such that, one group would collect data on speed, trafficflow, density, headway and the type of vehicle (percentage of truck)passing the study range site. Furthermore, prior to everything else,the first-hand procedures involved were as listed below:

  1. Preparing a team data collection plan.

  2. Designing a data collection sheet.

  3. Gathering data (unprocessed information).

The datagathering/collection was carried out in the following stages andmethods:

  • Speed measurement

Inthis category, we purposely applied the Pavement Marking procedureto obtain our much-needed data. Therefore, we made a trap linebetween two observers and placed pavement markings across the givenroad section. The first observer starts the stopwatch as a particularvehicle enters the trap line. The second observer had to ensure thatthe vehicle finished the trap threshold so that the other firstobserver could stop the watch at the end point. The benefit of thissimple method was that the markings could be easily re-changed.However, the main disadvantage was the introduction of errors andtrial sessions which might have wasted the time allocated before.

Figure2.Pavement marking (Speed Measurement)

  • Density

Sincethe density describes the vehicles per unit length, the procedure didnot make sense for a point measurement to a definite extent wasn’tinvolved. To achieve this principle, we used a camera positioned at aparticular distance from a pole. From the initial knowledge we had,the camera was supposed to observe about 0.5mi of the road length. Wemeasured the density at a single point in time (over a space intime). We also collected data on the peak hours (am-pm).

  • Traffic flow

Trafficflow rates are gathered directly from point measurements and timemeasurement. Hence, we observed this phenomenon by our eyes. Wecounted the number of vehicles passing a pre-defined section per thegiven hour. We counted on the northbound and southbound vehicles,differentiating among other cars and trucks on a left or right sidethe observations made at peak hours (am-pm). Immediately after thatwe recorded the data in the collection sheet.

  • Percentage of truck

Theproportion of trucks at the peak hours was determined by counting thenumber of actual trucks at a given traffic flow and also counting thetotal number of vehicles (including trucks) and recording the totals.The average truck number was divided by the total vehicle numbersthen multiplied by one hundred to get the % of trucks. Theobservation included the northbound, and the southbound left andright ways.

  • Highway Geometric layout

Toobserve this concept, we simply looked at the general highway designand appearance at a pre-defined section, and a range of 0.5mi optedfor since it also conformed to the study distance for density. Wefocused the study on the vertical and horizontal layouts. Entranceand street connections as well as the lanes and lanes’ widthpresent at the site. This observation was independent of time.

  • Headway

We measured theprogress using a chronograph and at the time where the front bumperof the first vehicle crossed the selected point, the start timerecorded. The front bumper of the second vehicle passed the similarpoint, and the time noted. Consequently, we recorded in seconds astime headway and in meters as space headway.

Results

Wecategorized the results obtained into details as illustrated below.

(Northbound)

Flow inputs and Adjustments

Volume, V

489

veh/h

Peak-hour factor, PHF

0.90

Peak 15-min volume, v15

136

V

Trucks and buses

22

%

Recreational vehicles

0

%

Terrain type

Level

Grade

0.00

%

Segment length

0.5

mi

Trucks and buses PCE, ET

1.5

Recreational vehicle PCE, ER

1.20

Heavy vehicle adjustment, fHV

0.901

Driver population factor, fp

1.00

Flow rate, vp

302

Pc/h/In

Table1

Speed inputs and Adjustments

Line width

12.0

ft

Right-shoulder lateral clearance

6.0

ft

Interchange density

0.50

interchange/mi

Number of lanes, N

2

Free-flow speeds

Measured

ffs or bff

70.0

mph

lane width adjustment, fLW

0.0

mph

lateral Clearance adjustment, fLC

0.0

mph

Interchange density adjustment, fID

0.0

mph

Number of lanes adjustment, fN

4.5

mph

Free-flow speed, FFS

70.0

mph

Table2

The HCS software wasused to determine the LOS is that Level of Service, as shown in Tablethree below.

Level of Service and Performance Measure

Free rate vp

302

pc/h/In

Free-flow speed FFS

70.0

mph

Average passenger-car speed S

70.0

mph

Number of lanes N

2

Density D

4.3

pc/mi/In

Tablethree

Wecould not compute the overall results if the free-flow speed wereless than 55 mph. The free-flow speed was 70.0 mph.

(Southbound)

Flow Inputs and Adjustments

(Southbound)

Volume V

506

veh/h

Peak-hour factor PHF

0.90

Peak 15-min volume v15

141

v

Trucks and buses

20

Recreation vehicles

0

Terrain type

Level

Grade

0.00

%

Segment length

0.5

mi

Trucks and buses PCE ET

1.5

Recreation vehicle PCE ER

1.2

Heavy vehicle adjustment fHV

0.909

Driver population factor fp

1.00

Flow rate vp

309

pc/h/ln

Table4

Speed Input and Adjustments

(Southbound)

Lane width

12.0

ft

Right-shoulder lateral clearance

6.0

ft

Interchange density

0.50

interchange

Number of lanes, N

2

Free-flow speed

measured

FFS or BFFS

70.0

mph

Lane width adjustment fLW

0.0

mph

Lateral clearance adjustments fLC

0.0

mph

Interchange density adjustment fID

0.0

mph

Number of lanes adjustment fN

4.5

mph

Free flow speed FFS

70.0

mph

Table5

Level of Service and Performance Measure

Southbound

Flow rate vp

309

pc/h/ln

Free-flow speed FFS

70.0

mph

Average passenger-car speed S

70.0

mph

Number of lanes N

2

Density D

4.4

pc/mi/ln

Table6

  • Kindly note that the speed and traffic flow results are shown in the attached Excel sheet documents together with this lab report. (Additional information)

Conclusion

Theanalysis period was one hour over a distance of 0.5mi. We recordedthe data from 4:45pm-5:45pm that was considered the peak hour. Wemade the observations from Bishop to Driscoll. Total number ofvehicles that were northbound was 489, and the total number ofvehicles that were southbound was 506. The number of cars was waymuch higher than that of trucks and buses. The average speed forsouthbound vehicles was 68 m/h while the average speed of thenorthbound vehicles was 64 m/h during the time of our study. Asexplained in the procedure the percentage truck was arrived at about19.69% for southbound vehicles and 21.67% for northbound vehiclesgiving an average of 20%.

The traffic flow fornorthbound and southbound vehicles was not steady, ranging from 51m/hand 78 m/has shown in the chart below.

Chart 1

The terrain type ofthe study area was level and has two lanes per way, each lanemeasuring a width of 12f.

We applied thePavement Marking method to measure the speed of the vehicles.Despite the method being simple there was the introduction of errorsand trial sessions which might have led to inaccurate results.

The importance ofthis project is to collect data on transit operations and usage forscheduling purposes and service planning. The data is also helpfulduring planning, prioritization and project initiation.

Traffic flow data isneeded for different purposes by various agencies, ministries, andorganizations.

The major areas thatuse this data in the field include

  • Planning maintenance

  • National Transport Statistics.

  • Highway and Road Safety Measures

WorkCited

Federal Highway Administration: US Department of Transportation:Texas Division and Texas Department of Transportation Driscoll Town,“Environmental Assessment.” US 77 Highway Journal: vol.1.(2014). 19-40.

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