The construction of safe havens and emergency access routes for the Highways Agency network

The UK Highways Agency is investigating the possibility of providing purpose built safe havens to protect broken down vehicles and their occupants.In a parallel initiative, the Highways Agency is looking at improving emergency entry to, and exit from, the trunk road network by provision of emergency turnaround areas in the roadside verge. Pilot-scale trials were undertaken in the TRL Pavement Test Facility to establish foundation designs to meet the anticipated design traffic and load-bearing requirement. Cellular concrete paving setts designed so that grass grows through (grass pavers) were used, so that the additional paving would be partially concealed to passing drivers. Six candidate systems were compared. Measurements of the bending strength of the systems were made. An unbound granular crushed rock sub-base on a subgrade clay was used as the foundation. The trials demonstrated that the predominant modes of distress of the two cellular paver systems under dynamic trafficking differed. In one system, the setts eventually began to crack and chip whereas in the other system, 'rocking' of the setts under trafficking caused by their manufactured profile eventually resulted in increased 'bedding in' of the setts into the underlying sandlayer that increased the overall surface deformation. Static load tests were carried out to simulate what would happen if a fully loaded lorry wasparked on the cellular pavers, its tractor unit removed and its trailer supported by propped legs. There was no evidence of shear failure in the unbound granular crushed rock sub-base but unsurprisingly the loaded concrete setts both fractured during the test. A full-scale field trial of the paving is considered necessary. Recommended design thicknesses for the full-scale trials are provided.

• Authors:
  • JONES, C
  • CHADDOCK, B
• Publication Date: 2007

Language

• English

Media Info

• Serial:
  • PUBLISHED ARTICLE
  • Issue Number: F/5798/07
  • Publisher: TRL

Subject/Index Terms

• TRT Terms: Base course (Pavements); Concrete; Emergencies; Highway design; Paved shoulders; Pavement design; Paving stones; Thickness; Traffic control; Vegetation
• Uncontrolled Terms: Unbound base
• ITRD Terms: 4755: Concrete; 2184: Emergency; 2916: Hard shoulder; 2855: Highway design; 3055: Pavement design; 4508: Sett (stone); 5933: Thickness; 654: Traffic control; 2970: Unbound base; 2488: Vegetation
• Subject Areas: Design; Highways; Materials; Operations and Traffic Management; Pavements; Planning and Forecasting; I21: Planning of Transport Infrastructure; I22: Design of Pavements, Railways and Guideways; I32: Concrete; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01082169
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Nov 29 2007 3:25PM