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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>PENNSYLVANIA COURT AFFIRMS REAL ESTATE EXCEPTION TO COMMONWEALTH'S SOVEREIGN IMMUNITY</title>
      <link>https://trid.trb.org/View/539887</link>
      <description><![CDATA[The husband of a motorist who was killed when an overhanging tree branch fell on her car sued the Pennsylvania Department of Transportation (PennDOT).  The trial court jury decided in favor of the motorist's estate.  Affirming the trial court's decision, the appeals court determined it was PennDOT's responsibility to know about the hazard created by topping the tree and leaving a disproportionately large limb over the roadway.  The appeals court agreed this dangerous condition came within the real estate exception to the commonwealth's sovereign immunity.]]></description>
      <pubDate>Wed, 21 Oct 1998 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/539887</guid>
    </item>
    <item>
      <title>SNOW AND ICE CONTROL - A CRITICAL LOOK AT ITS CRITICS</title>
      <link>https://trid.trb.org/View/110664</link>
      <description><![CDATA[SALT IS THE PRINCIPAL TOOL IN A HIGHLY ESSENTIAL OPERATION FINANCED WITH TAX FUNDS TO CONTROL SNOW AND ICE ON HIGHWAYS. MOST COMMONLY VOICED CRITICISMS OF DEICING CHEMICALS ARE DISCUSSED. SALT CAUSES AUTO CORROSION, KILLS TREES, GRASS AND SHRUBS, POLLUTES WATER SUPPLIES AND CAN POLLUTE LOCAL WELLS, PONDS AND STREAMS. MOST POLLUTION PROBLEMS RESULT FROM IMPROPER STORAGE OF DEICING SALTS. CHEMICAL PRODUCERS ARE READY TO ASSIST PUBLIC WORKS OFFICIALS IN PLANNING PROPER STORAGE FACILITIES. HOWEVER, THE POSITIVE ASPECTS OF DEICING SALT USE SHOW BY ACCIDENT STATISTICS, THE GREAT DECREASE IN ACCIDENTS AND SAVING OF LIVES BECAUSE OF ITS USE. CHICAGO ESTIMATES THAT ITS SNOW REMOVAL PROGRAM PREVENTED 15,250 ACCIDENTS THAT WOULD HAVE COST $3.71 MILLION.]]></description>
      <pubDate>Fri, 16 Sep 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/110664</guid>
    </item>
    <item>
      <title>SYMPOSIUM: POLLUTANTS IN THE ROADSIDE ENVIRONMENT</title>
      <link>https://trid.trb.org/View/99018</link>
      <description><![CDATA[THE EFFECTS ARE DISCUSSED OF SALT DEICING CHEMICALS ON PLANTS AND CROPLANDS BORDERING HIGHWAYS. IN ALL, NINE PAPERS WERE DEVOTED TO (1) THE PROBLEMS, (2) SNOW REMOVAL, (3) SALT MIGRATION IN SOIL, (4) THE RELATIONSHIP OF ROAD SALT APPLICATION TO SODIUM AND CHLORIDE ION LEVELS IN THE SOIL BORDERING MAJOR HIGHWAYS, (5) MOVEMENT OF DISSOLVED SALTS IN GROUND WATER SYSTEMS, (6) EFFECT OF DEICING CHEMICALS ON GRASSY PLANTS, (7) EFFECT OF DEICING CHEMICALS ON WOODY PLANTS, (8) SALT TOLERANCE ON ROADSIDE VEGETATION, AND (9) AIR POLLUTION IN THE ROADSIDE ENVIRONMENT.]]></description>
      <pubDate>Fri, 29 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/99018</guid>
    </item>
    <item>
      <title>THE EFFECT OF ROCK SALT UPON ROADSIDE SUGAR MAPLES IN CONNECTICUT</title>
      <link>https://trid.trb.org/View/110592</link>
      <description><![CDATA[INCREASING TRAFFIC AND PUBLIC DEMAND FOR ICE-FREE ROADS HAS LED TO INCREASED EMPLOYMENT OF ROCK SALT AND CALCIUM CHLORIDE FOR EFFICIENT AND ECONOMICAL DEICING OF ROADS. THESE RATES OF SALT APPLICATION, HOWEVER, ARE NOW SUSPECTED OF DAMAGING ROADSIDE VEGETATION. MEASUREMENTS ON TWO GROUPS OF SUGAR MAPLES WERE MADE TO ASSESS THE INFLUENCE OF SALT ON THE TREES AND ON TISSUE CONCENTRATIONS OF CHLORIDE, CALCIUM, POTASSIUM, MAGNESIUM, AND PHOSPHOROUS AND OF SODIUM. THE STUDIES REPORTED HAVE ESTABLISHED THAT TISSUE CONCENTRATIONS OF SODIUM AND CHLORIDE INCREASE WITH INCREASING EXPOSURE TO ROADSIDE DRAINAGE AND THAT EXPOSED TREES GENERALLY EXHIBIT MORE SEVERE SYMPTOMS OF DECLINING VIGOR AND CONTAIN LOWER CONCENTRATIONS OF SOME ESSENTIAL NUTRIENTS IN THEIR TISSUE. CONCENTRATIONS OF SODIUM AND CHLORIDE IN THE SAP SUGGESTED CHLORIDE UPTAKE BY MAPLES IS NORMALLY SLIGHT, BUT MAY INCREASE MARKEDLY AT TIMES, POSSIBLY REFLECTING EXPOSURE TO RUNOFF OF BRINE IN LATE WINTER OR EARLY SPRING.]]></description>
      <pubDate>Wed, 27 Apr 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/110592</guid>
    </item>
    <item>
      <title>RECONSTRUCTION OF MOTOR VEHICLE ACCIDENTS: A TECHNICAL COMPENDIUM. FRONTAL CRUSH ENERGY AND IMPULSE ANALYSIS OF NARROW OBJECT IMPACTS</title>
      <link>https://trid.trb.org/View/355193</link>
      <description><![CDATA[This paper examines methods of estimating the energy dissipated by the frontal crush of automobiles which impact narrow objects such as poles or trees. The method originally developed by Campbell for full frontal crashes is found to underestimate the energy for narrow object impacts by as much as 68 percent in those cases investigated. A correction factor equivalent to that used by NASS to account for induced bowing is found to improve the estimation in all cases investigated, improving the error to 37 percent in the worst case. An exploratory study using a previously reported technique of approximating a single high speed crash with a series of repeated low speed crashes is presented with promising results. The unique nature of narrow object impacts in impuulse analysis is also discussed. It is shown that the principal direction of force is not necessarily the same as the direction of crush of the car outer surface.]]></description>
      <pubDate>Tue, 30 Apr 1991 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/355193</guid>
    </item>
    <item>
      <title>SIX-YEAR GROWTH OF TREES AND SHRUBS ALONG MINNESOTA ROADS ESPECIALLY AS AFFECTED BY DEICING SALTS</title>
      <link>https://trid.trb.org/View/163751</link>
      <description><![CDATA[Deicing salt, chiefly sodium chloride, has been identified as an important cause of damage to roadside vegetation. A 1973 investigation along Minnesota roadways attempted to quantify the extent of the damage to roadside vegetation by deicing salt.  The 1973 study concluded that there was "no reason to expect widespread increases in salt damage" providing salt usage remained the same.  The objectives of this study was to verify these conclusions and to inventory tree growth along Minnesota roads through a re-measurement of the permanent plot system established for this purpose in 1973.  The purposes of the re-measurement were: (1) to provide data on species performance; (2) to determine how fast highway trees grow; (3) to assertain the amount of damage attributable to salt damage; and (4) to determine the likelihood of increased salt damage in the future.  The study concluded that; in general, the salt problem has not chnged since 1973 and tht the species tolerance ratings developed in 1973 are still valid.]]></description>
      <pubDate>Sat, 15 Aug 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/163751</guid>
    </item>
    <item>
      <title>PREJUDGEMENT CONCERNING AUTOMOBILE PROBLEMS</title>
      <link>https://trid.trb.org/View/54627</link>
      <description><![CDATA[The world's population has grown to 4.3 billion, against which the number of motor vehicles has risen to 270 million. The automobile has greatly benefited the development of human culture and society, but it also cannot be denied that the automobile has brought with it not a few demerits, such as traffic accidents and other social conflicts. People are sometimes apt to exercise prejudgement in rushing to hasty conclusions regarding the causes of social problems, particularly when the relationship between the origins and results are highly complex.  Such a situation exists in the realm of the automobile and the related problems.  In order to obtain a proper resolution of such problems and reduce the meaningless social costs, it is necessary to observe the actual situation coolly and objectively.  As examples of the type of hasty prejudgement found in the area of automobile problems, the following four questions will be introduced and examined by way of suggestion.  (1) Are there means of carrying goods which can be substituted for the automobile without lowering over level of life?  (2) Are emission gases from automobiles really the major cause of human health injury problems arising from Tokyo smog?  (3) Are such emission gases really the cause of the death of trees along the Fuji Subaru line?  (4) Are the currently applied car speeds really reasonable?  /Author/TRRL/]]></description>
      <pubDate>Wed, 12 Apr 1978 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/54627</guid>
    </item>
    <item>
      <title>EFFECT OF DEICING SALTS ON WOODY VEGETATION ALONG MINNESOTA ROADS</title>
      <link>https://trid.trb.org/View/42706</link>
      <description><![CDATA[Information was collected on amounts of deicing salts used and methods of application. Planting practices and investment were also surveyed. Techniques are presented for the recognition of soil-salt and spray-salt damage using visual symptoms and chemical analysis of leaves and soils. Proof was obtained that salt causes much of the twig dieback in hardwoods and needle browning in pines observed along certain Minnesota roadways. The locations are defined where salt-spray and soil-salt damage are likely to be high, moderate, or low. Species are rated for their sensitivity to soil-salts and winter spray-salts. A brief history of salt damage in Minnesota is presented, and the seriousness of current damage is evaluated in terms of mortality, reduced growth and disfigurement, and increased maintenance costs. Seven ways to reduce salt damage are presented including a planting guide to match species to site. Future prospects are estimated for salt damage in Minnesota. A permanent plot system is described that will monitor build up in plant and soil sodium and chloride as well as changes in the vegetation caused by salt damage.]]></description>
      <pubDate>Fri, 16 Sep 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/42706</guid>
    </item>
    <item>
      <title>SPRUCE BUDWORM DAMAGE EVALUATIONS USING AERIAL PHOTOGRAPHY</title>
      <link>https://trid.trb.org/View/65773</link>
      <description><![CDATA[The spruce budworn (Choristoneura fumiferana, Clem.) infestation is continuing at epidemic levels throughout northeastern North America's spruce-fir forest.  This article describes research to identify at which minimum scale aerial photography can be used to assess budworm damage.  Color and color-infrared imagery taken at several times of the year and interpreted by using several viewing methods have been evaluated to find if new infestations, tree mortality, and stands requiring spraying to prevent excessive future mortality can be identifed.  Color photography obtained in the summer at the height of needle browning was best for interpreting current moderate or heavy budworm feeding.  Early summer or fall photos taken when the currently fed needles were not on the trees were most suitable for evaluating past feeding and overall tree condition.  Mortality was best identified on color-infrared early summer or fall imagery.  Scale and viewing method greatly influenced interpretation accuracy.  Individual tree detail could be observed at scale of 825 feet- per-inch and larger.  Tree and stand condition were most accurately interpreted by using a 7X monocular viewer on the backlighted, outer portions of the frame.  Mortality counts were equally-accurate using two, four, or seven power stereoscopic and seven power monoscopic viewing at scales of 2640 feet-per-inch and larger.]]></description>
      <pubDate>Wed, 15 Dec 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/65773</guid>
    </item>
    <item>
      <title>WATER POLLUTION AND ASSOCIATED EFFECTS FROM STREET SALTING (ABRIDGMENT)</title>
      <link>https://trid.trb.org/View/140579</link>
      <description><![CDATA[The high rate of use of sodium chloride and calcium chloride for deicing, as well as poor storage and handling, have caused serious water pollution problems.  There has also been widespread damage to roadside soils, vegetation, and trees.  The EPA has initiated 4 projects in an attempt to better understand and control the road salt problem. The first project was a study that highlighted the need for more information on the effects of salt on the environment and man-made structures to allow accurate cost-benefit analyses of alternate approaches.  Research is now under way to identify an inexpensive hydrophobic or icephobic substance that would reduce ice adhesion when applied to the pavement (second project).  Economic analyses of salt damage and alternate methods are also being further explored (the third project).  The fourth project will determine methods of optimum salt use, develop a guide for salt storage and handling, and examine the ecological effect of dumping large quantities of snow from streets and highway into bodies or water supply watersheds.]]></description>
      <pubDate>Wed, 29 Jan 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/140579</guid>
    </item>
    <item>
      <title>STAKING LANDSCAPE TREES</title>
      <link>https://trid.trb.org/View/140225</link>
      <description><![CDATA[This paper suggests different staking techniques for providing, where necessary, adequate flexible support for trees in windy situations and reasonable protection with little or no tree injury. Reasons for supporting and protecting the tree with staking include protecting the trunk from damage by equipment, vehicles, and vandals; anchoring the root system; and supporting the trunk in an upright position. A young tree standing alone with its top free to move usually becomes a strong tree better able to withstand the elements. When support is essential, make the stakes as short as possible, but high enough to hold the tree upright under calm conditions; the tree should return to vertical after the wind has bent the top.]]></description>
      <pubDate>Tue, 31 Dec 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/140225</guid>
    </item>
    <item>
      <title>RODIOGRAPHY OF TREES AND WOOD PRODUCTS</title>
      <link>https://trid.trb.org/View/103369</link>
      <description><![CDATA[USDA FOREST SERVICE PERSONNEL HAVE DEVELOPED A MOBILE FIELD X-RAY UNIT AND RELATED NDT PROCEDURES FOR INSPECTING TREES AND WOOD PRODUCTS. A DESCRIPTION OF THE UNIT AND ITS POSSIBLE APPLICATIONS IS PRESENTED. THE DEVELOPMENT OF EXPOSURE CURVES FOR OAK, CONTROL OF SECONDARY RADIATION, AND CONTRUCTION OF WOODPENETRAMETERS IS DISCUSSED. THE UNIT WAS TESTED UNDER FOREST CONDITIONS IN KENTUCKY. CRYPTIC DISCONTINUITIES SUCH AS DECAY AND INSECT GALLERIES, AND MAN-MADE INCLUSIONS SUCH AS WIRE AND BUCKSHOT, WERE READILY DISCERNIBLE IN RADIOGRAPHS. THIS MOBIILE X-RAY UNIT HAS MANY APPLICATIONS IN FOREST AND SHADE TREE WORK. FOR EXAMPLE, TREE PATHOLOGISTS AND ENTOMOLOGISTS COULD USE IT TO INVESTI- GATE THE EXTENT OF INTERNAL INSECT DAMAGE AND DECAY IN TREES WHERE IT IS UNDESIRABLE TO CUT THEM; MUNICIPAL FORESTRY DEPARTMENT AND SHADE TREE COMPANIES COULD USE IT TO DETERMINE THE CONDITION OF STREET AND SHADE TREES. /DOT/]]></description>
      <pubDate>Mon, 19 Feb 1973 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/103369</guid>
    </item>
    <item>
      <title>A CHEMOTAXONOMIC APPROACH TO THE SELECTION OF OPOSSUM RESISTANT WILLOWS AND POPLARS FOR USE IN SOIL CONSERVATION</title>
      <link>https://trid.trb.org/View/119296</link>
      <description><![CDATA[THE LEVEL OF SALICIN AND ITS DERIVATIVES IN THE LEAVES OF A VARIETY OF POPLARS AND WILLOWS HAS BEEN DETERMINED QUANTITATIVELY. IT IS ESTABLISHED THAT A HIGH LEVEL OF SALICIN (OR SALICIN DERIVATIVES) CORRELATES BOTH WITH HIGH RELATIVE BITTERNESS AND WITH UNPALATABILITY TO OPOSSUM IN THESE PLANTS. A SEMIQUANTITATIVE THIN-LAYER CHROMATOGRAPHY METHOD FOR ASSESSING RELATIVE BITTERNESS IN THESE PLANTS AT THE NURSERY LEVEL IS DISCUSSED. /AUTHOR/]]></description>
      <pubDate>Sun, 15 Aug 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/119296</guid>
    </item>
    <item>
      <title>EFFECTS OF DE-ICING SALTS ON ROADSIDE SOILS AND VEGETATION</title>
      <link>https://trid.trb.org/View/110837</link>
      <description><![CDATA[THE PURPOSE OF THIS INVESTIGATION IS TO DETERMINE THE DISTRIBUTION AND MOVEMENT OF DEICING SALT IONS IN SOIL BORDERING THE HIGHWAY AT A SITE 5 MILES SOUTH OF SHELBURNE, VERMONT, ON US-7, AND TO DETERMINE THE POSSIBLE ROLE OF THESE SALTS IN CAUSING AN EXTENSIVE SILVER MAPLE DECLINE. THE STUDY INDICATES THAT HIGHWAY SALTING PRACTICES HAVE INCREASED THE SODIUM AND CHLORINE CONCENTRATIONS AND THE SPECIFIC CONDUCTANCE IN THE SOIL. THIS IS MANIFESTED IN AN EXTENSIVE SILVER MAPLE DECLINE ON THE EAST SIDE OF THE ROAD, WHILE HEALTHY TREES GROW ON THE WEST SIDE OF THE ROAD WHERE, DUE TO THE SLOPE, HIGHWAY DRAINAGE IS LIMITED. THE MAXIMUM CONCENTRATIONS OF SODIUM AND CHLORIDE ARE FOUND AT THE SOIL SURFACE AND NEAREST THE HIGHWAY PAVEMENT. SALT CONCENTRATIONS IN THE SOIL INCREASE DURING THE WINTER AND DECREASES DURING SUMMER AND FALL. SODIUM AND CHLORIDE IONS ENTER THE SOIL PROFILE DURING THE WINTER AND PENETRATE INTO DEEPER HORIZONS AS TIME PROGRESSES. HIGHER THAN NORMAL SODIUM AND CHLORIDE CONCENTRATIONS ARE FOUND TO DEPTHS OF 18 IN. AND DISTANCE OF 75 FT FROM THE PAVEMENT. AS THE YEARS PASS THE QUANTITY OF SODIUM AND CHLORIDE INCREASES THROUGHOUT THE ENTIRE SOIL PROFILE. THE PASSAGE OF SALT THROUGH SOIL PROFILES IS SUSPECTED TO CAUSE A DETERIORATION OF THE SOIL'S PHYSICAL PROPERTIES, THEREBY CAUSING A DECREASE IN SOIL PERMEABILITY. THE INCREASE IN SODIUM AND CHLORIDE CONTENT OF THE SOIL SOLUTION IS MANIFESTED THROUGH INCREASED UPTAKE OF THESE IONS INTO THE LEAVES AND STEMS OF THE DAMAGED TREES. DETERIORATION OF THE SILVER MAPLES RESULTED FROM CHLORIDE TOXICITY RATHER THAN FROM OSMOTIC EFFECT OF THE SALTS IN SOIL SOLUTION. NO DAMAGE IS OBSERVED WHEN THE CHLORIDE CONCENTRATION IS LESS THAN 0.18 PERCENT. A CHLORIDE CONCENTRATION OF 0.20 PERCENT PRODUCES LEAF SCORCH, AND ABOVE 0.50 PERCENT PRODUCES MODERATE LEAF SCORCH, DEFOLIATION, AND ULTIMATELY DEATH OF THE TREE. THE SODIUM CONCENTRATION IS MUCH HIGHER IN THE DAMAGED THAN IN THE HEALTHY TREES AND MAY BE A REASON FOR THE OVER-ALL DETERIORATION. HOWEVER, IT IS NOT TOTALLY RESPONSIBLE, AS HIGH CONCENTRATIONS OF SODIUM ARE SOMETIMES RECOVERED IN TREES EXHIBITING NO SALT DAMAGE WHEN DEATH OCCURS. CHLORIDE AND SODIUM ARE LOST FROM THE WOODY TISSUE. THEREFORE, TISSUE ANALYSIS OF A DEAD OR DYING TREE MAY FAIL TO REVEAL LARGE QUANTITIES OF THESE IONS. THE EFFECT OF SALT SPRAY APPEARS NEGLIGIBLE. THOUGH DEICING SALTS ARE DETRIMENTAL TO ROADSIDE VEGETATION, PUBLIC SAFETY DEMANDS THEIR USE, THEREFORE IT IS RECOMMENDED THAT WOODY VEGETATION BE LOCATED AS FAR FROM THE HIGHWAY AS PRACTICABLE WITH PAVEMENT DRAINAGE DIRECTED AWAY FROM THE TREES; ALSO THE SPECIES SHOULD BE CHOSEN ON THE BASIS OF SALT TOLERANCE.]]></description>
      <pubDate>Tue, 01 Jun 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/110837</guid>
    </item>
    <item>
      <title>METABOLIC INDEX AS A DIAGNOSTIC TOOL IN TREE HEALTH DETERMINATION</title>
      <link>https://trid.trb.org/View/104106</link>
      <description><![CDATA[IN ORDER TO DEVELOP A TOOL FOR EVALUATING THE DETRIMENTAL EFFECT OF EXPOSURE OF TREES TO CHLORIDE AND SODIUM IONS FROM DEICING MATERIALS, A STUDY OF THE LEVELS OF CALCIUM, MAGNESIUM, PHOSPHORUS AND POTASSIUM IONS ALSO FOUND IN PLANT TISSUE IS MADE. THE RESULTS OF ANALYSES OF TISSUE SAMPLES OF SUGAR MAPLES AT 3 LOCATIONS IN CONNECTICUT FROM 1964-1967 ARE ASSESSED FOR 4 TREE GROUPS. THE RELATIONSHIP OF THE ION LEVELS TO TREE HEALTH IS EXPRESSED BY THE INDEX, DEFINED AS THE RATIO OF CALCIUM, MAGNESIUM, PHOSPHORUS AND POTASSIUM IONS TO SODIUM AND CHLORIDE IONS. THESE IONS ARE EXPRESSED AS A PERCENTAGE OF DRY WEIGHT OF THE TISSUE. SINCE LEAF TISSUE RESPONDS MORE RAPIDLY AND AT A HIGHER LEVEL THAN TWIG TISSUE FROM THE SAME LOCATION OF THE SAME TREE, THE CALCULATION MADE FOR THE LEAF TISSUE IS KNOWN AS THE LEAF INDEX. THIS INDEX PROVIDES INFORMATION ON THE EFFECT OF SALT ON THE YOUNGEST CELL TISSUE OF THE SAME TREE. SINCE SODIUM AND CHLORIDE IONS GRADUALLY ACCUMULATE IN THE WOODY TISSUE OF THE TREES THAT ARE CONTINUOUSLY SUBJECTED TO SALT, STUDYING THE LEVELS OF THESE IONS IN WOODY TISSUES OVER A PERIOD OF TIME PROVIDES INFORMATION ON THE GRADUAL DETERIORATION POTENTIALITY OF THE TREE. HENCE THE SAME CALCULATION IS EMPLOYED BY USING THE IONS FOUND IN THE TWIG TISSUE TO DERIVE A TWIG INDEX. THE METABOLIC CONDITION OF A TREE CAN THEN BE EXPRESSED AS THE MEAN OF THE SUM OF THE INDICES: METABOLIC INDEX = LEAF INDEX + TWIG INDEX DIVIDED BY TWO. THE METABOLIC INDEX OFFERS A REALISTIC EVALUATION OF THE CUMULATIVE EFFECT OF EXPOSURE OF ROADSIDE SUGAR MAPLES TO CHLORIDE AND SODIUM IONS POLLUTING FROM THE ROOT ZONE SOIL FROM HIGHWAY SALT APPLICATIONS. IT IS PROPOSED THAT OTHER INVESTIGATORS EXPLORE THIS METHOD OF EVALUATION TO ASSESS THE EFFECT OF SALT ON THE GENERAL HEALTH OF ROADSIDE TREES.]]></description>
      <pubDate>Tue, 01 Jun 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/104106</guid>
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