Paved Shoulders

    Road Shoulders,  properly built and well maintained,  not only land structure of support to various layers of payment,  but also provide additional space for overtaking  maneuvers,  parking of disabled vehicles and movement of low moving vehicles such a scooters two wheeler three wheelers and bicycles.  in this manner shoulder help to reduce accidents and increase Road safety on the other side,  shoulders in poor shape that is those having Deep ruts  and deformed profile,  constitute traffic hazard beside affecting payment performance to an appreciable degree thereby increasing the total transportation cost.

Criteria for paved Shoulders

To get capacity benefit from shoulders specially under mixed traffic conditions, Depending on availability of funds,  1.5 m wide paid shoulder maybe provided on either side of two lane national highways in plain/ rolling Terrain in a selective manner. Ad regards four in sections,  it is already in policy of the ministry to construct  paid shoulders in conjunction with the four laning. 

While initiating proposal for pure shoulders on to learn sections,  the following should be kept in view

1.  the present traffic on national highway should be generally around 10000 PCUs or more

2.  the traffic should Consist of sizable percentage of slow moving vehicles

 Apart from above provisions of Shoulders could also be considered when.

A. The concerned section is located in or near and urbanized area with considerable local traffic 

Or

B. A stretch is particularly accident prone mainly due to lack of paved with for overtaking and passing maneuvers.

Final selection of lengths would be according to priority given to each section on the basis of traffic intensity  and/or Safety consideration and overall availability of funds.

Thickness of paved Shoulders

Fig. A - New/ Existing Road

Fig. B - Existing Road

As far as practicable paved shoulders when constructed simultaneously with the central payment should have the same thickness as pavement of the main carriageway (See fig. A) in the case of old National Highways Where The crust composition and thickness is variable and not well defined, shoulder thickness could be fixed in an ad hoc manner (see fig B) Otherwise it would be as in fig. A.

Notes:-

1. (e + 1)% cross fall shall not be less than 2.5 to 3% on granular shoulder and 3 to 4% on earth shoulder - steeper values shall be used for rainfall exceeding 150 cm per year.

2.On Super elevated sections the shoulders should have same cross fall as the pavement.

Typical design of a paved shoulder will thus consist of: 

i) Suitable thickness of granular subways with the bottom 150 mm portion preferably extended over the full formation to ensure efficient drainage.

ii) A base course of water bound macadam (W.B.M.) or Wet Mix Macadam (W.M.M.) In three layers of 75 mm each with the top layer being primed and 

iii) A beauty minus wearing course consisting of two quotes of surface dressing, premix carpet,  concrete mix seal or semi-dense bituminous concrete carpet. The texture of the shoulder wearing surface should be different from the main carriageway to ensure clear contrast between them. 

Shoulder cross section 

Typical cross sections of a national highway with paid shoulders are shown in the enclosed sketches (figure A and B).

 the paid shoulders should invariably be flanked by one meter wide Earth berms. When feasible the berms may be made of granular materials .

General considerations

Paved shoulders should not be provided in piecemeal manner without giving due consideration to other improvements on the road section in question in the near future. Desirable the construction of shoulders should be taken up in homogeneous sections and preferably together with strengthening of the main payment .

Simultaneous with the provision of paved shoulders, narrow cross drainage structures in the concerned section must also be widened to full formation width.

The carriageway and paved shoulders must be distinguished from each other by continuous yellow edge line marking. 

Construction sequences 

Where the paid shoulders is to be provided by the side of an existing carriageway the sequence of construction shall be

i) strengthening of the pavement if envisaged

ii) Construction of shoulder on one side if the carriageway including earthen link

iii) construction of shoulder on the opposite side

 step (iii) will be proceed with only after step (ii) is completed.

In the case of new road construction,  payment and paved shoulders on both sides of carriageway should be constructed simultaneously in corresponding layers.