The construction and widening of existing National highway 2-lane to 4-lane is a very difficult task in hilly terrain especially in lower Himalaya as being a fragile Geology.As 4-lane road widening is in progress on large scale under different schemes of government especially under Bharatmala projects in the state of Himachal, Uttrakhand, Jammu & Kashmir and North West region of India. During construction, up gradation and widening of a existing highway, huge quantities of excavation are involved in hilly terrain which triggered frequently slope instabilities not only at hill side but also towards at valley side. If Hill cut slope excavation works is not executed carefully with proper proper input of Geological and geotechnical investigation it resulted a lot of direct and indirect consequence related to safety and cost. The vulnerability of these cut slopes are increase drastically due to unscientific excavation. It is well known that development and widening of any road in hilly terrain is not so simple as in plains. The construction and widening cost estimate is always higher than a plain area. In most of cases this exercise is not dealt properly at DPR stage which resulted many problem during construction stage.
The DPR is prepared with short duration without carry out proper geotechnical investigation. In few DPR it is observed that the proper Cut slope protection measures are not provided in details with chainage wise. That is create a big problem during construction stage as contractors not addressed this exercise properly due to unavailability of a good professional. In other side it is also noted that lack of detailed topographic, geological/geotechnical and hydrological investigation, the hilly road project suffer badly to achieved its targeted mile stone, especially in front of cut slope excavation and stability and protection measures of these vulnerable cut slope. In most of project a hill slope excavation is carried out in a tradition manner to minimize excavation quantities. And there is no proper care has been taken about geometry of cut slope including various geological, hydrological and geotechnical parameters like cut slope SMR, angle and orientation of cut slope with respect to road alignment, strength of strata, unfavorable discontinuity etc. Lack of consideration of all above parameters, cut slope instabilities are triggered during cutting of hill slope as well as after construction of the highway. Sometimes it has resulted man made chronic landslide on mountainous highway.
There are several problems have been encountered during planning and execution of a highway work as fallows—
1. LA and Forest clearance issues: During DPR the land acquisition is not carry out properly keep in mind about high hill and deep gorges. Land requirement to get proper ROW: Land execution with a proper ROW is an another problem to achieved all geometric standard in a hilly steep terrain. If there is no proper ROW width acquired there is a big problem arises to self stabilize hill cut slope. If the self stabilize slope not plane than it required additional protection measures at few stretch where geological and geotechnical factor are unfavorable. This exercise has not been one in most of cases due to unavailability of good expertise. Generally short ROW issues arise during construction stage. It requires more time as mentioned with given milestone. Secondly clearance of forest withing ROW is also a major issues during execution of work . At least permission of forest clearance must be in han at the time of appointment date.
2. Alignment issues: Horizontal and vertical alignment problem is generally arises during planning an widening of hilly mountainous terrain as having high relief, gorges and rugged topography. There is a most common problem encountered to acquire a proper ROW to provide better curvature and cut slope angle with a uniform application of design standard. So it is necessary that the best geometric requirement of hilly highway is keeps in mind from beginning at DPR stage.
3. Lack of planning and investigation for Cut slope excavation: No detailed investigation datas have been collected during DPR as well as detailed investigation analysis as per required standard. When a hilly road poorly planned without proper geotechnical/geological investigation may lead to destabilization of hill cut slope as well as sometimes complete washout of highway. Which create big issues in later stage to complete the project target milestone. These are resulted huge direct and indirect consequences with project cost and safety. It is better for contractors to go for pile foundation in spite of open excavation for structure's foundation. The detailed scope of cut slope with protection work must be given clearly in Schl. B for Contractors.
4. Lack of Planning and design of Cut slope excavation work: cue to lack of geological and geotechnical datas and improper planning of hill slope excavation work. There are a instabilities triggered on cut slope with providing simultaneously protection measures. The excavation work even carried out without providing required berm with respect to slope height. No proper cut slope sections have been developed based on geological and geotechnical investigation. Excavation work have been executed in tradition way. No systematic data have been recorded during excavation. So it is very essential to carry out a detailed investigation before fixing final alignment of road widening with considering all parameters especially geological/geotechnical including hill slope characteristics. At the DPR stage. uring PR stage we must explore viaduct provision in spite of providing hill cutting, If viaduct provision not possible possible then at least we must plan both carriageway on different grade (different level) to avoid high cutting.
5. Lack of professional expertise for Hill road: As 4-lane works in Himalayas started recently so there is a lack of field expertise. Widening for a 4-lane with all standard is very difficult task than 2-lane in Himalayan terrain. So development of 4-lane work required skilled well experienced professional to execute to work in time bond manner. The execution staff of contractor must be well competent for hilly project and must be appointed after review the CV by competent Authority.
6. High risk of natural calamities: Himalayan terrain is full of natural calamities. Natural Landslide triggered by heavy rain, Cloud burst, snow fall and earthquake. There are several difficulties encountered during construction and widening of highway in hilly terrain.
7. Lack of good drainage planning: It is generally observed that no good drainage planing is provided during detailed planing of the project. There is no hydrogeological mapping conducted neither at DPR stage nor during execution stage. Perfect vertical an horizontal drainage must be provided for a long life of a highway project. The selection criteria for contractors must be based on QCBC (Quality cum cost selection) pattern.
