STUDIES OF CONDITIONS FOR VEGETATION IN THE CENTRAL RESERVES OF MOTORWAYS: A PRELIMINARY REPORT

Measurements have been made of exchangeable sodium levels in the soils of central reserves and verges of motorways, resulting from the use of rock salt for winter maintenance; some limited work on total lead in soil was included. Measurements made at a number of sites throughout the UK showed considerable variation, the contrast between exchangeable sodium levels for the M4 near Hounslow and the M62 over the pennines being especially marked. Values for exchangeable sodium during the winter 1973/74 remained essentially constant on the M4 but, on the M62 rose to over 1500 ppm and remained high until August. Degrees of damage to vegetation have been reported in other countries at levels lower than those found in the study. More detailed investigations showed steep concentration gradients across central reserves. At the one site where a complete transect was taken across a motorway, the levels on the verges were generally lower than on the central reserves; the exchangeable sodium content of the soil was not significantly affected beyond two metres from the hard shoulders. The curvature of the motorway seemed to have little effect. In contrast, lead levels were found to be high in the south (on the M4) but low in the north.(a) /TRRL/

• Corporate Authors:

  Transport and Road Research Laboratory (TRRL)

  Wokingham, Berkshire  United Kingdom 
• Authors:
  • COLWILL, D M
  • Thompson, J R
  • Ridout, P S
• Publication Date: 1976

Language

• English

Media Info

• Features: Figures; Photos; References; Tables;
• Pagination: 19 p.

Subject/Index Terms

• TRT Terms: Concentration (Chemistry); Freeways; Halite; Lead (Metal); Medians; Paved shoulders; Road shoulders; Snow and ice control; Sodium; Sodium chloride; Sodium chloride; Vegetation
• Uncontrolled Terms: Concentration
• ITRD Terms: 2914: Central reserve; 7132: Concentration (chem); 2916: Hard shoulder; 7138: Lead (metal); 2752: Motorway; 7197: Sodium; 2488: Vegetation
• Subject Areas: Design; Environment; Highways;

Filing Info

• Accession Number: 00142767
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Report/Paper Numbers: TRRL Supp Rpt. 217UCMonograph
• Files: ITRD, TRIS, ATRI
• Created Date: Jul 19 1977 12:00AM