Highway Traffic, 1942

By IRA L. WOOD TRAFFIC STATISTICIAN Arizona Highway Planning Survey Arizona Highway Department FROM various sources, the Arizona Highway Planning Survey obtains data to keep in touch with the volume and type of traffic flowing over the State Highway and Secondary or feeder road Federal aid systems. Traffic information for the State Highway system is obtained from two different sources: manual counts at strategically-located intersections, and from six fixed electric traffic recorders. Manual counts are taken once a month at important intersections controlling traffic breaks; at less important intersections four times a year; and at some intersections only twice a year. Information from manual counts is used to determine the type, nature and amount of traffic for the hour periods during which the counts are taken. The six fixed electric traffic recorders record traffic 24 hours a day, every day of the year. Factors developed from these recorders are used to expand the manual traffic counts into 24-hour annual average traffic that flows over the State Highway system. The traffic flow map accompanying this article is one way of depicting traffic information for the year 1942. A much more detailed record of traffic information as of the State Highway system is kept year by year in book form.

TRAFFIC FLOW OVER U.S. AND STATE NUMBERED ROUTES FOR THE YEAR 1942

This map tells the story of traffic over the U. S. and State numbered routes for the year, 1942. Despite travel curtailment caused by the war, traffic fell only 17.84 per cent as compared to the previous year. Some roads integrated with the State system showed marked increase in traffic because of defense activity, so much so, that overall 1942 motor vehicle consumption fell only 5.09 percent. Foreign traffic over the state system showed a drop of 34.33 per cent for 1942 as compared to 1941 In 1942 field operation was commenced to obtain information as to traffic, type, nature and habits on the Federal-aid Secondary system, generally known as the farm-to-market and mine-to-market roads. Traffic on these roads is obtained with portable recorders. At present a log as of the lengths of the various surface types and widths with corresponding traffic information is being made, and will in the near future be set up in book form in somewhat the same manner as the record that is kept of traffic year by year for the State Highway System.

It would be hard to determine the monetary value of traffic information. Possibly the many requests for different phases of traffic information are the best criterion of its value to civilian life. Last year this department furnished to twenty universities and libraries traffic data relative to trucking tonnage as of export, import and trans-State. Nearly every day some firm dealing with the traveling public requests traffic information of this department. One firm wished traffic information to obtain priority on vulcanizing equipment. At present traffic information is needed to obtain priorities on certain road materials for maintenance and reconstruction.

To the State Highway Department, traffic in-formation is a basic figure in allotting monies for maintenance and construction. After the na-tional emergency is past and road rehabilitation is taking place, a continuity of past traffic rec-ords will prove invaluable to the State Highway Department in allotting monies for new construction and reconstruction work.

In 1942 traffic was anything but static; its monthly variation is probably best depicted by chart No. 2 that shows the monthly motor vehicle fuel consumption.

The following tabulation shows the average densities, weighted by vehicle miles traveled over the State Highway system, for the past four years: Foreign traffic, i. e., passenger cars registered in states other than Arizona, showed a slight increase over the corresponding months of 1941. However, from March, 1942, on to the end of the year, foreign traffic decreased to a considerable extent, the total decrease for the year being 34.33 per cent, and accounted for the major decrease shown in the preceding tables.

Although traffic on the State Highway system decreased, due principally to a decrease in foreign traffic, traffic on other road systems as a whole showed a slight increase. The increase on these roads was due mainly to increased agriculture and mining activities. Also, the locations of defense projects were such that roads integrated with the State Highway system showed a marked increase of traffic. Inasmuch as traffic on the State Highway system is approximately 50% of all traffic, the 17.84% decrease on this system accounts for the 5.09% decrease in the 1942 motor vehicle fuel consumption.

As may be seen by the following tabulation, the decrease in commercial vehicle traffic was all in the single-unit truck classification. The tabulation shows the average densities, weight It may be noted from the trend tabulation that the heavy combinations are gradually replacing the single-unit trucks on the State Highway system. However, it may be pointed out that the replacement occurs principally on what is termed long hauls.

The history of motor vehicle fuel consumption is the record of all traffic on all roads and streets in the State.

Chart No. 1 depicts the annual motor vehicle fuel consumption for the years 1925 to 1942. The gallonage shown is the net taxed gallons, and represents the gallonage consumed by vehicles of private ownership.

Gas rationing, curtailment of automobile and tire manufacturing will in the next few years greatly reduce the consumption of motor vehicle fuel. However, when the national emergency is over, the consumption of motor vehicle fuel will increase, and in all probability by approximately 6,700,000 gallons a year as during the years between 1933 and 1941.

Chart No. 2 depicts the monthly motor vehicle fuel consumption for the years 1940, 1941 and 1942. The erratic nature of the monthly

Comparing 1942 traffic with 1941 as shown in the preceding table gives the following results:

During the first two months of 1942 foreign

Influenced by vehicle miles traveled over the State Highway system, for the years 1936, 1940, 1941 and 1942:

The trend of trucking types in terms of per cent based on the preceding tabulation is as follows: Consumption for 1942 is due to a considerable extent to the fluctuation of foreign traffic that in former years had a dependable seasonal curve, whereas in 1942 foreign traffic was anything but static.

Construction of defense projects, etc., also had a marked influence on motor vehicle fuel consumption.

In November, 1942, the net taxed motor vehicle fuel sales reached an all-time peak, due probably to the final splurge and the desire of the owners of vehicles registered in other States to be in their own bailiwick prior to rationing, rather than to any great increase in business or defense traffic during that month.

In 1942 a study was made, supervised by the Arizona Highway Planning Survey, of the 1942 inter-State and trans-State trucking of Arizona. Data for this study were taken from the Commercial Vehicle Station reports of the Motor Vehicle Division. The findings of this study were published in August, 1942. It is thought that a few short tabulations, excerpts from the original publication, might prove of interest to the readers of this article.

The following tabulation relative to load groupings clearly shows one reason, i. e., the greater carried loads, why the tractor-truck combination and the truck and trailer combi-nation are replacing the single-unit truck on long hauls, as was brought out in discussing trends of trucking types:

PER CENT OF LOADED TRUCKS AND TRUCKING COMBINATIONS BY VARIOUS CARRIED LOAD GROUPS

Total 100.00 100.00 100.00 In the carried load group tabulation under truck and trailer combination, 40 out of every 100 loads in the 30,000 to 34,999 lb load group ing were loads of cattle exported to California. In the same tabulation under the same heading, 92 out of every 100 loads in the 35,000 to 39,999 lb. load grouping were loads of gasoline and other oil refinery products imported prin cipally from California.

The following tabulation shows the 1941 trucking tonnage as of carried load that crossed the Arizona border. Your attention is called to one item in this tabulation, i. e., the 274,957 ton manufactures and miscellaneous. Of the tons quoted, 206,755 were gasoline and other products of oil refineries.

CARRIED LOAD 1941 TRUCKING TONNAGE

Total 227,028 556,797 159,076 942,901 The following tabulation will probably prove of interest to the residents of the various coun ties in Arizona, as it shows the number of tons. carried load, exported and imported by each county in 1941.

Total 227,028 556,797 In 1942 the State Highway Department was forced to replace timber stringers in several bridges. The failure of the stringers was at tributed to the severe pounding inflicted by heavy truck loads.

In March, 1942, the Arizona Highway Planning Survey submitted a letter to the Public Roads Administration asking for ap proval to conduct a trucking survey to deter mine the character and nature of trucking Destructive to bridges and highways in Ari zona. Approval was obtained and field work began in April, 1942.

The finds have proved helpful in many ways. However, the greatest potential value of the survey lies in the information gleaned that will prove of value in helping to enact uniform trucking legislation by the various States.

The following tabulation, an excerpt from the original report, shows in terms of per cent the inter-State nature of trucking loads weigh ed in Arizona that are considered destructive to highway surface and bridges. The tabula tion shows the origin and destination by States of loads of 800 and over "C" value. The highest value of "C" in the formula C= L+40 in which L is the distance in feet between the first and last axle of the vehicle, or of any interior group of axles, and W is the total weight of the vehicle of any interior group of axles, was used to determine the value of "C."

The value of "C" taking into consideration the weight, length, and the factor 40, is generally used to determine load concentration on bridges and surfacing, and by this determina tion the value 800 is considered the maximum safe load limit.

ORIGIN AND DESTINATION OF TRUCKING LOADS OF 800 AND OVER "C" VALUE

Total 100.00 100.00 The facts and figures as related in this article are but a few of the findings that are gleaned each year by the Arizona Highway Planning Survey in its research of the var ious phases of traffic, facts and figures that are used not only by the State Highway De partment in planning future roads and future road construction, but by various business con cerns that cater to the traveling public.

The scientific study of highway traffic in Arizona by the Arizona Highway Planning Survey of the Arizona Highway Department is valuable for post-war planning as well as keeping an accurate picture of month by month travel trends. Not only is careful check made of the volume of traffic but an itemized breakdown is also tabulated of the various types of vehicles in the flow, valuable information for the engineer and the road planner.