Insignificant lengths of new highways are added each year as funds allocated for the purpose are mainly eaten-up in maintaining the existing road network.
Our highways are mostly flexible type asphalt highways, with a life of hardly 10 years and that too, requiring heavy maintenance cost right from the year one. The transportation networks are key to development and are to be developed to last a minimum period of 20-30 years with least possible annual maintenance cost.
In order to meet the transportation requirements beyond 2003, the existing national network and the inter-district highways will have to be substantially improved to meet the international standards. Also, rigid concrete (RCP) and continuously reinforced concrete pavements (CRCP) need to be built for providing a network that will be durable, long-lasting and economical to maintain.
Types: flexible asphalt roads and highways are currently being built, the main categories of which are:
(a): motor ways ; (b) national ways; (c) district highways; (d) farms-to-market roads and (e) city roads.
Except for the motorways which meet the international standard, all other roads and highways hardly meet specification limits of flexible asphalt roads and thus have short life with heavy annual maintenance cost.
International highways: Two types of highways are built all over the world and they are:
(1) flexible type with asphalt surface; (2) rigid type with asphalt surface: a. rigid concrete pavement (RCP) and b. rigid continuously reinforced concrete pavement (CRCP).
The rigid type highways are much better than flexible type highways. The main advantages viz-a-viz durability and long life are:
Flexible type highways have a 10 to 17 years life with heavy maintenance cost coming at end year 3, 5 and 10 against a 27-40 years long life of RCP and CRCP highways with minimum maintenance cost.
The rigid highways cost more, but save money in longer life compared to cheaper flexible highways which are costly to operate and fail in early stages of operational life.
In order to bring the roads/highways up to the international standards, a log normally distributed gravel sand clay layer varying in thickness from 0.7 to 1 foot and depending on load requirement, will need to be placed over the compacted base for all flexible type asphalt highways. This is likely to ensure a life of 10-15 years with least maintenance cost.
For a long lasting life of 27-40 years, an eight inch thick concrete (RCP) or continuously reinforced concrete slab (CRCP), will need to be placed over 0.7 to 1 foot thick gravel layer. These cemented highways (RCP and CRCP types) are sure to support a 100-150 km/hr heavy traffic for a longer period with negligible maintenance cost.
Cost estimation: Approximation of cost has been made on the basis of prevailing material cost with a generous 200 per cent burden. It excludes the cost of the top asphalt crush layer which will be common to flexible and rigid type pavements.
Thus per kilometer cost for a 3.65 meter wide strip pavement will be as follows: Table 1.
Compatibility: The World Bank projects of highways rehabilitation envisages an outlay of $125 million which is to cover 525kms of highway improvement and rehabilitation and 320kms of highway re-surfacing and strengthening. (The Engineer, Vol. 40 No.12 December, 2002).
Supposing that $100 million is utilized on re-structuring, re-strengthening and re-surfacing of 845kms of existing flexible type highway the per kilometre cost would come to Rs6.91 million. This is 300 per cent higher than the cost estimated for constructing a new flexible type highway.
Model planning: If a planning for constructing 1650kms of single and double strip (3.65m single strip ) highways is made and executed, it will result in a network of 16,500kms of excellent, durable and long lasting highways in about 10 years time. The following is the break-up of costs of pavements with requirement of cement. Tables-2.
Benefits: (1) A modest annual programme of Rs16.385 billion with some additional cost for asphalt surfacing is likely to develop international standards flexible and rigid type highways totalling 1650kms. These will include 400kms of double strip and 500kms of single strip cemented highways, and 500kms length of flexible highways.
(2). Development of total 1150kms of cemented lengths of highways is to require about 13.6 to 18.4 per cent additional cement production over the approximate Pakistan annual production of 10 million tonnes.
(3). Construction of highways, in general is done under public sector allowance of rebate, subsidy or waiver on excise duty and GST equalling to Rs1,400/ton cement is likely to help in the development of additional lengths of cemented (RCP) highways.
(4) waiving of excise duty could help in executing a bigger annual programme of building rigid type highways.
(5) Building of international standard flexible and rigid type highways is surely to boost transportation of agricultural and industrial products and thus help in overall increase of production on national scale.